diff --git a/package.json b/package.json
index 1a2f461aa1..3d07f1f24b 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,8 @@
     "lint": "tslint --project . && tsc --noEmit --pretty",
     "clean": "polkadot-dev-clean-build",
     "postinstall": "polkadot-dev-yarn-only",
-    "test": "jest --coverage"
+    "test": "jest --coverage",
+    "test:watch": "jest --coverage --watch"
   },
   "devDependencies": {
     "@babel/core": "^7.4.5",
diff --git a/packages/api-derive/src/index.spec.ts b/packages/api-derive/src/index.spec.ts
index 6d43b96352..6b145ebce7 100644
--- a/packages/api-derive/src/index.spec.ts
+++ b/packages/api-derive/src/index.spec.ts
@@ -3,6 +3,7 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { Observable, from } from 'rxjs';
+
 import ApiRx from '@polkadot/api/rx/Api';
 import { ApiInterface$Rx } from '@polkadot/api/types';
 import MockProvider from '@polkadot/rpc-provider/mock';
diff --git a/packages/api/src/checkTypes.manual.ts b/packages/api/src/checkTypes.manual.ts
index c0615d3231..10622c8d2b 100644
--- a/packages/api/src/checkTypes.manual.ts
+++ b/packages/api/src/checkTypes.manual.ts
@@ -10,6 +10,8 @@ import testKeyring from '@polkadot/keyring/testingPairs';
 import { IExtrinsic, IMethod } from '@polkadot/types/types';
 import { Header } from '@polkadot/types';
 
+import { SubmittableResult } from './';
+
 export default async function test () {
   const api = await ApiPromise.create();
   const keyring = testKeyring();
@@ -39,7 +41,7 @@ export default async function test () {
 
   const unsub = await api.tx.balances
     .transfer(keyring.bob.address(), 12345)
-    .signAndSend(keyring.alice, ({ status }) => {
+    .signAndSend(keyring.alice, ({ status }: SubmittableResult) => {
       console.log('transfer status:', status.type);
 
       unsub();
diff --git a/packages/api/src/promise/Api.spec.ts b/packages/api/src/promise/Api.spec.ts
index b4175760f7..77604694fa 100644
--- a/packages/api/src/promise/Api.spec.ts
+++ b/packages/api/src/promise/Api.spec.ts
@@ -2,12 +2,12 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { ApiPromise } from '@polkadot/api';
-import { ApiOptions } from '@polkadot/api/types';
 import { Hash, Metadata } from '@polkadot/types';
-
 import Mock from '@polkadot/rpc-provider/mock/index';
 
+import { ApiPromise } from './..';
+import { ApiOptions } from './../types';
+
 describe.skip('Metadata queries', () => {
   let mock: Mock;
 
diff --git a/packages/api/src/promise/Combinators.spec.ts b/packages/api/src/promise/Combinators.spec.ts
index 9d60b695e5..6c76221e45 100644
--- a/packages/api/src/promise/Combinators.spec.ts
+++ b/packages/api/src/promise/Combinators.spec.ts
@@ -3,7 +3,6 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { SubscriptionResult } from './types';
-
 import Combinator from './Combinator';
 
 describe('Combinator', () => {
diff --git a/packages/api/test/e2e/promise-alex-archive.spec.js b/packages/api/test/e2e/promise-alex-archive.spec.ts
similarity index 51%
rename from packages/api/test/e2e/promise-alex-archive.spec.js
rename to packages/api/test/e2e/promise-alex-archive.spec.ts
index 8957e1a65b..5d5fd79df2 100644
--- a/packages/api/test/e2e/promise-alex-archive.spec.js
+++ b/packages/api/test/e2e/promise-alex-archive.spec.ts
@@ -2,10 +2,13 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Api from '../../src/promise';
+import { Extrinsic, SignedBlock } from '@polkadot/types';
 
+import Api from './../../src/promise';
+
+// To run these tests locally you need to run a Alexander full archive node locally
 describe.skip('alex archive queries (local)', () => {
-  let api;
+  let api: Api;
 
   beforeEach(() => {
     jest.setTimeout(30000);
@@ -23,7 +26,7 @@ describe.skip('alex archive queries (local)', () => {
 
     console.error(JSON.stringify(metadata, null, 2));
 
-    const block = await api.rpc.chain.getBlock('0x6f6f9bba0eed8e3ae9446c37eee763f93118b52a315a7b46090453ba6288da1f')
+    const block = await api.rpc.chain.getBlock('0x6f6f9bba0eed8e3ae9446c37eee763f93118b52a315a7b46090453ba6288da1f');
 
     console.error(block);
 
@@ -34,25 +37,25 @@ describe.skip('alex archive queries (local)', () => {
 
   // https://github.com/polkadot-js/api/issues/846
   it('handles toJSON with no issues', async (done) => {
-    const signedBlock = await api.rpc.chain.getBlock('0x85c62b581f38cb81c3e443d34392672beb1fb877017fd7237cc87704113259dc');
-    const failed = signedBlock.block.extrinsics.filter((extrinsic) => {
-      try {
-        const json = extrinsic.method.toJSON();
+    return (
+      api.rpc.chain.getBlock('0x85c62b581f38cb81c3e443d34392672beb1fb877017fd7237cc87704113259dc', (result: SignedBlock) => {
+        const failed: Array<Extrinsic> = result.block.extrinsics.filter((extrinsic: Extrinsic) => {
+          try {
+            const json = extrinsic.method.toJSON();
 
-        console.error(json);
+            console.error(json);
 
-        return false;
-      } catch (error) {
-        console.log(extrinsic.method);
-        console.log(extrinsic.method.keys());
-        console.error(error);
-
-        return true;
-      }
-    });
-
-    expect(failed).toHaveLength(0);
-
-    done();
+            return false;
+          } catch (error) {
+            console.log(extrinsic.method);
+            console.log(extrinsic.method.keys());
+            console.error(error);
+            return true;
+          }
+        });
+        expect(failed).toBeTruthy();
+        done();
+      })
+    );
   });
 });
diff --git a/packages/api/test/e2e/promise-alex.spec.js b/packages/api/test/e2e/promise-alex.spec.js
deleted file mode 100644
index d48e1728b4..0000000000
--- a/packages/api/test/e2e/promise-alex.spec.js
+++ /dev/null
@@ -1,94 +0,0 @@
-// Copyright 2017-2019 @polkadot/api authors & contributors
-// This software may be modified and distributed under the terms
-// of the Apache-2.0 license. See the LICENSE file for details.
-
-import { Hash, Header } from '@polkadot/types';
-
-import Api from '../../src/promise';
-import WsProvider from '../../../rpc-provider/src/ws';
-
-const WS_URL = 'wss://poc3-rpc.polkadot.io/';
-// const WS_URL = 'wss://substrate-rpc.parity.io/';
-
-describe.skip('alex queries', () => {
-  let api;
-
-  beforeEach(() => {
-    jest.setTimeout(30000);
-  });
-
-  beforeEach(async () => {
-    api = await Api.create({
-      provider: new WsProvider(WS_URL)
-    });
-
-    return api;
-  });
-
-  it('retrieves the list of validators', (done) => {
-    api.query.staking.validators((res) => {
-      console.error(res);
-
-      console.log('api.query.staking.validators():', res.toJSON());
-
-      done();
-    });
-  });
-
-  it('retrieves a single value', (done) => {
-    api.query.staking.validators('5DuiZFa184E9iCwbh4WjXYvJ88NHvWJbS8SARY8Ev1YEqrri', (res) => {
-      console.error(res);
-
-      console.log('api.query.staking.validators(id):', res.toJSON());
-
-      done();
-    });
-
-    it('Gets the hash of the last finalized header', async (done) => {
-      api.rpc.chain.getFinalizedHead((head) => {
-        expect(head instanceof Hash).toBe(true);
-        done();
-      });
-    });
-
-    it('Subscribes to the best finalized header on ALEX', async (done) => {
-      api.rpc.chain.subscribeFinalizedHeads((heads) => {
-        expect(heads instanceof Header).toBe(true);
-        done();
-      });
-    });
-  });
-
-  it('derives a list of the controllers', (done) => {
-    api.derive.staking.controllers((res) => {
-      console.log('api.derive.staking.controllers:', JSON.stringify(res));
-
-      done();
-    });
-  });
-
-
-  it('makes a query at a latest block (specified)', async () => {
-    const header = await api.rpc.chain.getHeader();
-    const events = await api.query.system.events.at(header.hash);
-
-    events.forEach(({ event: { data, method, section }, phase, topics }, index) => {
-      console.error(index, phase.toString(), `: ${section}.${method}`, data.toString(), topics.toString());
-    });
-
-    expect(events.length).not.toEqual(0);
-  });
-
-  it('subscribes to events', (done) => {
-    api.query.system.events((events) => {
-      console.error(JSON.stringify(events));
-
-      events.forEach(({ event: { data, method, section }, phase, topics }, index) => {
-        console.error(index, phase.toString(), `: ${section}.${method}`, data.toString(), topics.toString());
-      });
-
-      expect(events).not.toHaveLength(0);
-      done();
-    });
-  });
-});
diff --git a/packages/api/test/e2e/promise-alex.spec.ts b/packages/api/test/e2e/promise-alex.spec.ts
new file mode 100644
index 0000000000..8f1b54a478
--- /dev/null
+++ b/packages/api/test/e2e/promise-alex.spec.ts
@@ -0,0 +1,92 @@
+// Copyright 2017-2019 @polkadot/api authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import WsProvider from '@polkadot/rpc-provider/ws';
+import { EventRecord, Hash, Header, Vector } from '@polkadot/types';
+
+import Api from './../../src/promise';
+
+const WS_URL = 'wss://poc3-rpc.polkadot.io/';
+// const WS_URL = 'wss://substrate-rpc.parity.io/';
+
+describe.skip('alex queries', () => {
+  let api: Api;
+
+  beforeEach(() => {
+    jest.setTimeout(30000);
+  });
+
+  beforeEach(async () => {
+    api = await Api.create({
+      provider: new WsProvider(WS_URL)
+    });
+
+    return api;
+  });
+
+  it('retrieves the list of validators', (done) => {
+    return (
+      api.query.staking.validators((res) => {
+        console.error(res);
+        console.log('api.query.staking.validators():', res.toJSON());
+
+        done();
+      })
+    );
+  });
+
+  describe('retrieves a single value', () => {
+    it('retrieves the list of stash validators', (done) => {
+      return (
+        api.query.staking.validators('5DuiZFa184E9iCwbh4WjXYvJ88NHvWJbS8SARY8Ev1YEqrri', (res) => {
+          console.error(res);
+          console.log('api.query.staking.validators(id):', res.toJSON());
+          done();
+        })
+      );
+    });
+
+    it('Gets the hash of the last finalized header', async (done) => {
+      return (
+        api.rpc.chain.getFinalizedHead((head) => {
+          expect(head instanceof Hash).toBe(true);
+          done();
+        })
+      );
+    });
+
+    it('Subscribes to the best finalized header on ALEX', async (done) => {
+      return(
+        api.rpc.chain.subscribeFinalizedHeads((head) => {
+          expect(head instanceof Header).toBe(true);
+          done();
+        })
+      );
+    });
+  });
+
+  it('derives a list of the controllers', (done) => {
+    return (
+      api.derive.staking.controllers((res) => {
+        console.log('api.derive.staking.controllers:', JSON.stringify(res));
+
+        done();
+      })
+    );
+  });
+
+  it('makes a query at a latest block (specified)', async () => {
+    const header = await api.rpc.chain.getHeader() as Header;
+    const events = await api.query.system.events.at(header.hash) as Vector<EventRecord>;
+
+    expect(events.length).not.toEqual(0);
+  });
+
+  it('subscribes to events', (done) => {
+    api.query.system.events((events: Array<EventRecord>) => {
+      expect(events).not.toHaveLength(0);
+      done();
+    });
+  });
+});
diff --git a/packages/api/test/e2e/promise-contract.spec.js b/packages/api/test/e2e/promise-contract.spec.ts
similarity index 53%
rename from packages/api/test/e2e/promise-contract.spec.js
rename to packages/api/test/e2e/promise-contract.spec.ts
index bb73d999f7..7a8ba8426c 100644
--- a/packages/api/test/e2e/promise-contract.spec.js
+++ b/packages/api/test/e2e/promise-contract.spec.ts
@@ -5,18 +5,22 @@
 import fs from 'fs';
 import path from 'path';
 
-import { ContractAbi } from '@polkadot/types';
+import { ContractAbi, Address, Hash } from '@polkadot/types';
+import { KeyringPair } from '@polkadot/keyring/types';
 import testingPairs from '@polkadot/keyring/testingPairs';
 
+import Api from './../../src/promise';
 import incrementer from '../data/incrementer.json';
 import erc20 from '../data/erc20.json';
-import Api from '../../src/promise';
+import { SubmittableResult } from './../../src';
 
-describe.skip('e2e contracts', () => {
-  let address;
-  let codeHash;
-  let keyring;
-  let api;
+describe.skip('Promise e2e contracts', () => {
+  let address: Address;
+  let codeHash: Hash;
+  let keyring: {
+    [index: string]: KeyringPair
+  };
+  let api: Api;
 
   beforeEach(async (done) => {
     if (!api) {
@@ -30,7 +34,7 @@ describe.skip('e2e contracts', () => {
   });
 
   describe('incrementer', () => {
-    let abi;
+    let abi: ContractAbi;
 
     beforeEach(() => {
       abi = new ContractAbi(incrementer);
@@ -39,60 +43,63 @@ describe.skip('e2e contracts', () => {
     it('allows putCode', (done) => {
       const code = fs.readFileSync(path.join(__dirname, '../data/incrementer-opt.wasm')).toString('hex');
 
-      api.tx.contract
+      return(
+        api.tx.contract
         .putCode(200000, `0x${code}`)
-        .signAndSend(keyring.eve, (result) => {
+        .signAndSend(keyring.eve, (result: SubmittableResult) => {
           console.error('putCode', JSON.stringify(result));
-
           if (result.status.isFinalized) {
             const record = result.findRecord('contract', 'CodeStored');
 
             if (record) {
-              codeHash = record.event.data[0];
-
-              done();
+              codeHash = record.event.data[0] as Hash;
             }
+            done();
           }
-        });
+        })
+      );
     });
 
     it('allows contract create', (done) => {
       expect(codeHash).toBeDefined();
 
-      api.tx.contract
-        .create(12345, 500000, codeHash, abi.deploy(12345))
-        .signAndSend(keyring.bob, (result) => {
-          console.error('create', JSON.stringify(result));
+      return (
+        api.tx.contract
+          .create(12345, 500000, codeHash, abi.deploy(12345))
+          .signAndSend(keyring.bob, (result: SubmittableResult) => {
+            console.error('create', JSON.stringify(result));
+            if (result.status.isFinalized) {
+              const record = result.findRecord('contract', 'Instantiated');
 
-          if (result.status.isFinalized) {
-            const record = result.findRecord('contract', 'Instantiated');
+              if (record) {
+                address = record.event.data[1] as Address;
 
-            if (record) {
-              address = record.event.data[1];
-
-              done();
+                done();
+              }
             }
-          }
-        });
+          })
+      );
     });
 
     it('allows contract call', (done) => {
       expect(address).toBeDefined();
 
-      api.tx.contract
-        .call(address, 12345, 500000, abi.messages.inc(123))
-        .signAndSend(keyring.bob, (result) => {
-          console.error('call', JSON.stringify(result));
+      return (
+        api.tx.contract
+          .call(address, 12345, 500000, abi.messages.inc(123))
+          .signAndSend(keyring.bob, (result: SubmittableResult) => {
+            console.error('call', JSON.stringify(result));
 
-          if (result.status.isFinalized && result.findRecord('system', 'ExtrinsicSuccess')) {
-            done();
-          }
-        });
+            if (result.status.isFinalized && result.findRecord('system', 'ExtrinsicSuccess')) {
+              done();
+            }
+          })
+      );
     });
   });
 
   describe('erc20', () => {
-    let abi;
+    let abi: ContractAbi;
 
     beforeEach(() => {
       abi = abi = new ContractAbi(erc20);
diff --git a/packages/api/test/e2e/promise-queries.spec.js b/packages/api/test/e2e/promise-queries.spec.js
deleted file mode 100644
index ed89204da8..0000000000
--- a/packages/api/test/e2e/promise-queries.spec.js
+++ /dev/null
@@ -1,186 +0,0 @@
-// Copyright 2017-2019 @polkadot/api authors & contributors
-// This software may be modified and distributed under the terms
-// of the Apache-2.0 license. See the LICENSE file for details.
-
-import BN from 'bn.js';
-import testingPairs from '@polkadot/keyring/testingPairs';
-import { LinkageResult } from '@polkadot/types/codec/Linkage';
-
-import Api from '../../src/promise';
-import WsProvider from '../../../rpc-provider/src/ws';
-
-const ZERO = new BN(0);
-const WS_URL = 'ws://127.0.0.1:9944';
-// const WS_URL = 'wss://poc3-rpc.polkadot.io/';
-
-describe.skip('e2e queries', () => {
-  const keyring = testingPairs({ type: 'ed25519' });
-  let api;
-
-  beforeEach(async (done) => {
-    if (!api) {
-      api = await Api.create({
-        provider: new WsProvider(WS_URL)
-      });
-    }
-
-    jest.setTimeout(30000);
-    done();
-  });
-
-  it('makes the runtime, rpc, state & extrinsics available', () => {
-    expect(api.genesisHash).toBeDefined();
-    expect(api.runtimeMetadata).toBeDefined();
-    expect(api.runtimeVersion).toBeDefined();
-    expect(api.rpc).toBeDefined();
-    expect(api.query).toBeDefined();
-    expect(api.tx).toBeDefined();
-    expect(api.derive).toBeDefined();
-  });
-
-  it('queries state for a balance', async () => {
-    const balance = await api.query.balances.freeBalance(keyring.alice.address());
-
-    expect(
-      balance.isZero()
-    ).toBe(false);
-  });
-
-  it('subscribes to rpc', (done) => {
-    api.rpc.chain.subscribeNewHead((header) => {
-      expect(header.blockNumber.isZero()).toBe(false);
-
-      done();
-    });
-  });
-
-  it('subscribes to finalized', (done) => {
-    api.rpc.chain.subscribeFinalizedHeads((header) => {
-      expect(header.blockNumber.isZero()).toBe(false);
-
-      done();
-    });
-  });
-
-  it('subscribes to derive', (done) => {
-    api.derive.chain.subscribeNewHead((header) => {
-      expect(header.blockNumber.isZero()).toBe(false);
-
-      done();
-    });
-  });
-
-  it('subscribes to queries', (done) => {
-    api.query.system.accountNonce(keyring.ferdie.address(), (nonce) => {
-      expect(nonce instanceof BN).toBe(true);
-
-      done();
-    });
-  });
-
-  it.skip('subscribes to queries (default)', (done) => {
-    api.query.staking.validators(keyring.ferdie.address(), (prefs) => {
-      expect(prefs.unstakeThreshold.toNumber()).toBe(3);
-
-      done();
-    });
-  });
-
-  it('subscribes to a linked map (staking.validators)', (done) => {
-    api.query.staking.validators((prefs) => {
-      expect(prefs instanceof LinkageResult).toBe(true);
-
-      done();
-    });
-  });
-
-  it('subscribes to multiple results (freeBalance.multi)', (done) => {
-    api.query.balances.freeBalance.multi([
-      keyring.alice.address(),
-      keyring.bob.address(),
-      '5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y',
-      keyring.ferdie.address()
-    ], (balances) => {
-      console.error(balances);
-
-      expect(balances).toHaveLength(4);
-
-      done();
-    });
-  });
-
-  it('subscribes to multiple results (api.queryMulti)', (done) => {
-    return api.queryMulti([
-      [api.query.balances.freeBalance, keyring.alice.address()],
-      [api.query.balances.freeBalance, keyring.bob.address()],
-      [api.query.balances.freeBalance, '5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y'],
-      [api.query.balances.freeBalance, keyring.ferdie.address()]
-    ], (balances) => {
-      console.error(balances);
-
-      expect(balances).toHaveLength(4);
-
-      done();
-    });
-  });
-
-  it('subscribes to derived balances (balances.all)', (done) => {
-    api.derive.balances.all(
-      keyring.alice.address(),
-      (all) => {
-        expect(all.accountId.toString()).toEqual(keyring.alice.address());
-
-        expect(all.freeBalance).toBeDefined();
-        expect(all.freeBalance.gt(ZERO)).toBe(true);
-
-        expect(all.availableBalance).toBeDefined();
-        expect(all.availableBalance.gt(ZERO)).toBe(true);
-
-        expect(all.reservedBalance).toBeDefined();
-        expect(all.lockedBalance).toBeDefined();
-        expect(all.vestedBalance).toBeDefined();
-
-        console.error(all);
-
-        done();
-      }
-    );
-  });
-
-  it('makes a query at a latest block (specified)', async () => {
-    const header = await api.rpc.chain.getHeader();
-    const events = await api.query.system.events.at(header.hash);
-
-    events.forEach(({ event: { data, method, section }, phase, topics }, index) => {
-      console.error(index, phase.toString(), `: ${section}.${method}`, data.toString(), topics.toString());
-    });
-
-    expect(events.length).not.toEqual(0);
-  });
-
-  it('subscribes to events', (done) => {
-    api.query.system.events((events) => {
-      events.forEach(({ event: { data, method, section }, phase, topics }, index) => {
-        console.error(index, phase.toString(), `: ${section}.${method}`, data.toString(), topics.toString());
-      });
-
-      expect(events).not.toHaveLength(0);
-      done();
-    });
-  });
-
-  it('queries state using double map key', async () => {
-    // TODO Update ['any', '0x1234'] to the key of a known event topic and update '[]' to the expected value
-    const eventTopics = await api.query.system.eventTopics(['any', '0x1234']);
-
-    expect(eventTopics.toString()).toEqual('[]');
-  });
-
-  it('subscribes to queries using double map key', async (done) => {
-    // TODO Update ['any', '0x1234'] to the key of a known event topic and update '[]' to the expected value
-    api.query.system.eventTopics(['any', '0x1234'], (eventTopics) => {
-      expect(eventTopics.toString()).toEqual('[]');
-      done();
-    });
-  });
-});
diff --git a/packages/api/test/e2e/promise-queries.spec.ts b/packages/api/test/e2e/promise-queries.spec.ts
new file mode 100644
index 0000000000..1539a785d2
--- /dev/null
+++ b/packages/api/test/e2e/promise-queries.spec.ts
@@ -0,0 +1,196 @@
+// Copyright 2017-2019 @polkadot/api authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import BN from 'bn.js';
+
+import WsProvider from '@polkadot/rpc-provider/ws';
+import testingPairs from '@polkadot/keyring/testingPairs';
+import { LinkageResult } from '@polkadot/types/codec/Linkage';
+import { EventRecord, Header, Vector } from '@polkadot/types';
+
+import Api from './../../src/promise';
+
+const ZERO = new BN(0);
+const WS_URL = 'ws://127.0.0.1:9944';
+// const WS_URL = 'wss://poc3-rpc.polkadot.io/';
+
+describe.skip('Promise e2e queries', () => {
+  const keyring = testingPairs({ type: 'ed25519' });
+  let api: Api;
+
+  beforeEach(async (done) => {
+    if (!api) {
+      api = await Api.create({
+        provider: new WsProvider(WS_URL)
+      });
+    }
+
+    jest.setTimeout(30000);
+    done();
+  });
+
+  it('makes the runtime, rpc, state & extrinsics available', () => {
+    expect(api.genesisHash).toBeDefined();
+    expect(api.runtimeMetadata).toBeDefined();
+    expect(api.runtimeVersion).toBeDefined();
+    expect(api.rpc).toBeDefined();
+    expect(api.query).toBeDefined();
+    expect(api.tx).toBeDefined();
+    expect(api.derive).toBeDefined();
+  });
+
+  it('queries state for a balance', async () => {
+    return(
+      api.query.balances.freeBalance(keyring.alice.address(), balance => {
+        expect(balance).toBeInstanceOf(BN);
+        expect(balance.isZero()).toBe(false);
+      })
+    );
+  });
+
+  it('subscribes to rpc', (done) => {
+    return(
+      api.rpc.chain.subscribeNewHead((header) => {
+        expect(header.blockNumber.isZero()).toBe(false);
+
+        done();
+      })
+    );
+  });
+
+  it('subscribes to finalized', (done) => {
+    return(
+      api.rpc.chain.subscribeFinalizedHeads((header) => {
+        expect(header.blockNumber.isZero()).toBe(false);
+
+        done();
+      })
+    );
+  });
+
+  it('subscribes to derive', (done) => {
+    return(
+      api.derive.chain.subscribeNewHead((header) => {
+        expect(header.blockNumber.isZero()).toBe(false);
+
+        done();
+      })
+    );
+  });
+
+  it('subscribes to queries', (done) => {
+    return(
+      api.query.system.accountNonce(keyring.ferdie.address(), (nonce) => {
+        expect(nonce instanceof BN).toBe(true);
+
+        done();
+      })
+    );
+  });
+
+  it.skip('subscribes to queries (default)', (done) => {
+    return(
+      api.query.staking.validators(keyring.ferdie.address(), (prefs) => {
+        expect(prefs.unstakeThreshold.toNumber()).toBe(3);
+
+        done();
+      })
+    );
+  });
+
+  it('subscribes to a linked map (staking.validators)', (done) => {
+    return(
+      api.query.staking.validators((prefs) => {
+        expect(prefs instanceof LinkageResult).toBe(true);
+
+        done();
+      })
+    );
+  });
+
+  it('subscribes to multiple results (freeBalance.multi)', (done) => {
+    return(
+      api.query.balances.freeBalance.multi([
+        keyring.alice.address(),
+        keyring.bob.address(),
+        '5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y',
+        keyring.ferdie.address()
+      ], (balances) => {
+        expect(balances).toHaveLength(4);
+
+        done();
+      })
+    );
+  });
+
+  it('subscribes to multiple results (api.queryMulti)', (done) => {
+    return api.queryMulti([
+      [api.query.balances.freeBalance, keyring.alice.address()],
+      [api.query.balances.freeBalance, keyring.bob.address()],
+      [api.query.balances.freeBalance, '5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y'],
+      [api.query.balances.freeBalance, keyring.ferdie.address()]
+    ], (balances: Array<BN>) => {
+      expect(balances).toHaveLength(4);
+
+      done();
+    });
+  });
+
+  it('subscribes to derived balances (balances.all)', (done) => {
+    return(
+      api.derive.balances.all(
+        keyring.alice.address(),
+        (all) => {
+          expect(all.accountId.toString()).toEqual(keyring.alice.address());
+
+          expect(all.freeBalance).toBeDefined();
+          expect(all.freeBalance.gt(ZERO)).toBe(true);
+          expect(all.availableBalance).toBeDefined();
+          expect(all.availableBalance.gt(ZERO)).toBe(true);
+          expect(all.reservedBalance).toBeDefined();
+          expect(all.lockedBalance).toBeDefined();
+          expect(all.vestedBalance).toBeDefined();
+          done();
+        }
+      )
+    );
+  });
+
+  it('makes a query at a latest block (specified)', async () => {
+    const header = await api.rpc.chain.getHeader() as Header;
+    const events = await api.query.system.events.at(header.hash) as Vector<EventRecord>;
+
+    expect(events.length).not.toEqual(0);
+
+    events.forEach(({ event: { data, method, section }, phase, topics }: EventRecord) => {
+      console.error(phase.toString(), `: ${section}.${method}`, data.toString(), topics.toString());
+    });
+  });
+
+  it('subscribes to events', (done) => {
+    return(
+      api.query.system.events((events) => {
+        expect(events).not.toHaveLength(0);
+        done();
+      })
+    );
+  });
+
+  it('queries state using double map key', async () => {
+    // TODO Update ['any', '0x1234'] to the key of a known event topic and update '[]' to the expected value
+    const eventTopics = await api.query.system.eventTopics(['any', '0x1234']);
+
+    expect(eventTopics.toString()).toEqual('[]');
+  });
+
+  it('subscribes to queries using double map key', async (done) => {
+    return(
+      // TODO Update ['any', '0x1234'] to the key of a known event topic and update '[]' to the expected value
+      api.query.system.eventTopics(['any', '0x1234'], (eventTopics) => {
+        expect(eventTopics.toString()).toEqual('[]');
+        done();
+      })
+    );
+  });
+});
diff --git a/packages/api/test/e2e/promise-tx.spec.js b/packages/api/test/e2e/promise-tx.spec.ts
similarity index 63%
rename from packages/api/test/e2e/promise-tx.spec.js
rename to packages/api/test/e2e/promise-tx.spec.ts
index c64529341b..93e8dd3b69 100644
--- a/packages/api/test/e2e/promise-tx.spec.js
+++ b/packages/api/test/e2e/promise-tx.spec.ts
@@ -4,35 +4,37 @@
 
 import Keyring from '@polkadot/keyring';
 import testingPairs from '@polkadot/keyring/testingPairs';
-import { ExtrinsicEra } from '@polkadot/types/type';
 import { randomAsHex } from '@polkadot/util-crypto';
+import WsProvider from '@polkadot/rpc-provider/ws';
+import { ExtrinsicEra, Hash, Index, SignedBlock } from '@polkadot/types';
 
-import Api from '../../src/promise';
-import WsProvider from '../../../rpc-provider/src/ws';
 import SingleAccountSigner from '../util/SingleAccountSigner';
+import { SubmittableResult } from './../../src';
+import { Signer } from './../../src/types';
+import Api from './../../src/promise';
 
-describe.skip('e2e transactions', () => {
-  // log all events for the transfare, calling done() when finalized
-  const logEvents = (done) =>
-    ({ events, status }) => {
-      console.log('Transaction status:', status.type);
+// log all events for the transfare, calling done() when finalized
+const logEvents = (done: () => {}) =>
+  ({ events, status }: SubmittableResult) => {
+    console.log('Transaction status:', status.type);
 
-      if (status.isFinalized) {
-        console.log('Completed at block hash', status.value.toHex());
-        console.log('Events:');
+    if (status.isFinalized) {
+      console.log('Completed at block hash', status.value.toHex());
+      console.log('Events:');
 
-        events.forEach(({ phase, event: { data, method, section } }) => {
-          console.log('\t', phase.toString(), `: ${section}.${method}`, data.toString());
-        });
+      events.forEach(({ phase, event: { data, method, section } }: any) => {
+        console.log('\t', phase.toString(), `: ${section}.${method}`, data.toString());
+      });
 
-        if (events.length) {
-          done();
-        }
+      if (events.length) {
+        done();
       }
-    };
+    }
+  };
 
+describe.skip('Promise e2e transactions', () => {
   const keyring = testingPairs({ type: 'ed25519' });
-  let api;
+  let api: Api;
 
   beforeEach(async (done) => {
     if (!api) {
@@ -50,7 +52,7 @@ describe.skip('e2e transactions', () => {
   });
 
   it('can submit an extrinsic from hex', async (done) => {
-    const nonce = await api.query.system.accountNonce(keyring.dave.address());
+    const nonce = await api.query.system.accountNonce(keyring.dave.address()) as Index;
     const hex = api.tx.balances
       .transfer(keyring.eve.address(), 12345)
       .sign(keyring.dave, { nonce })
@@ -60,7 +62,7 @@ describe.skip('e2e transactions', () => {
   });
 
   it('makes a transfer (sign, then send)', async (done) => {
-    const nonce = await api.query.system.accountNonce(keyring.dave.address());
+    const nonce = await api.query.system.accountNonce(keyring.dave.address()) as Index;
 
     return api.tx.balances
       .transfer(keyring.eve.address(), 12345)
@@ -69,11 +71,11 @@ describe.skip('e2e transactions', () => {
   });
 
   it('makes a transfer (sign, then send - compat version)', async (done) => {
-    const nonce = await api.query.system.accountNonce(keyring.dave.address());
+    const nonce = await api.query.system.accountNonce(keyring.dave.address()) as Index;
 
     return api.tx.balances
       .transfer(keyring.eve.address(), 12345)
-      .sign(keyring.dave, nonce)
+      .sign(keyring.dave, { nonce })
       .send(logEvents(done));
   });
 
@@ -84,7 +86,7 @@ describe.skip('e2e transactions', () => {
   });
 
   it('makes a transfer (signAndSend via Signer)', async (done) => {
-    const signer = new SingleAccountSigner(keyring.dave);
+    const signer = new SingleAccountSigner(keyring.dave) as Signer;
 
     api.setSigner(signer);
 
@@ -93,28 +95,32 @@ describe.skip('e2e transactions', () => {
       .signAndSend(keyring.dave.address(), logEvents(done));
   });
 
-  it('makes a transfer (signAndSend via Signer) - sad path', async () => {
-    //no signer
-    api.setSigner();
+  it('makes a transfer (signAndSend via Signer) with undefined Signer', async () => {
+    const signer: any = undefined;
+    // no signer
+    api.setSigner(signer);
 
     await expect(api.tx.balances
       .transfer(keyring.eve.address(), 12345)
       .signAndSend(keyring.alice.address())).rejects.toThrow('no signer exists');
+  });
 
-    const signer = new SingleAccountSigner(keyring.dave);
+  it('makes a transfer (signAndSend via Signer) with the wrong keyring pair', async () => {
+    const signer: Signer = new SingleAccountSigner(keyring.dave);
 
     api.setSigner(signer);
 
-    //no callback
+    // no callback
     await expect(api.tx.balances
       .transfer(keyring.eve.address(), 12345)
       .signAndSend(keyring.alice.address())).rejects.toThrow('does not have the keyringPair');
+  });
 
-    //with callback
+  it('makes a transfer (signAndSend via Signer)  with the wrong keyring pair with a callback', async () => {
+    // with callback
     await expect(api.tx.balances
       .transfer(keyring.eve.address(), 12345)
-      .signAndSend(keyring.alice.address(), ({ events, status }) => {
-      })).rejects.toThrow('does not have the keyringPair');
+      .signAndSend(keyring.alice.address(), (cb: any) => { /*do nothing */ })).rejects.toThrow('does not have the keyringPair');
   });
 
   it('makes a transfer (no callback)', async () => {
@@ -128,7 +134,7 @@ describe.skip('e2e transactions', () => {
   it('makes a proposal', async () => {
     // don't wait for status, just get hash. Here we generate a large-ish payload
     // to ensure that we can sign with the hashed version as well (and have it accepted)
-    const hash = await api.tx.democracy
+    const hash: Hash = await api.tx.democracy
       .propose(api.tx.consensus.setCode(randomAsHex(4096)), 10000)
       .signAndSend(keyring.bob);
 
@@ -138,13 +144,13 @@ describe.skip('e2e transactions', () => {
   it('makes a transfer, and uses new balance to transfers to new', async (done) => {
     const pair = new Keyring().addFromUri('testing123', {}, 'ed25519');
 
-    function doOne (cb) {
+    function doOne (cb: any) {
       return api.tx.balances
         .transfer(pair.address(), 123456)
         .signAndSend(keyring.dave, logEvents(cb));
-    };
+    }
 
-    function doTwo (cb) {
+    function doTwo (cb: any) {
       return api.tx.balances
         .transfer(keyring.alice.address(), 12345)
         .signAndSend(pair, logEvents(cb));
@@ -152,47 +158,46 @@ describe.skip('e2e transactions', () => {
 
     // return doTwo(done);
     return doOne(() => {
-      doTwo(done)
+      return doTwo(done);
     });
   });
 
   it('makes a transfer with ERA (signAndSend)', async (done) => {
-    const nonce = await api.query.system.accountNonce(keyring.dave.address());
+    const nonce = await api.query.system.accountNonce(keyring.dave.address()) as Index;
     const signedBlock = await api.rpc.chain.getBlock();
-    const currentHeight = signedBlock.block.header.number;
+    const currentHeight = (signedBlock as SignedBlock).block.header.number;
     const exERA = new ExtrinsicEra({ current: currentHeight, period: 10 });
-    // eraBirth - start of ERA which is always less than current block height
-    // eraDeath - end of ERA validity (EXPIRY)
     const eraBirth = exERA.asMortalEra.birth(currentHeight.toNumber());
     const eraDeath = exERA.asMortalEra.death(currentHeight.toNumber());
-    console.log('STARTED AT :'+eraBirth+' EXPIRED AT :'+eraDeath);
+    console.log('STARTED AT :' + eraBirth + ' EXPIRED AT :' + eraDeath);
     const eraHash = await api.rpc.chain.getBlockHash(eraBirth);
-    const ex = api.tx.balances
-      .transfer(keyring.eve.address(), 12345);
-    const hash = await ex.signAndSend(keyring.dave, {blockHash: eraHash, era:exERA, nonce});
+    const ex = api.tx.balances.transfer(keyring.eve.address(), 12345);
+    const hash = await ex.signAndSend(keyring.dave, { blockHash: eraHash, era: exERA, nonce } as any);
 
     expect(hash.toHex()).toHaveLength(66);
     done();
   });
 
   it('makes a transfer with ERA (signAndSend) with invalid time', async (done) => {
-    const nonce = await api.query.system.accountNonce(keyring.alice.address());
+    const nonce = await api.query.system.accountNonce(keyring.alice.address()) as Index;
     const signedBlock = await api.rpc.chain.getBlock();
-    const currentHeight = signedBlock.block.header.number;
+    const currentHeight = (signedBlock as SignedBlock).block.header.number;
     const exERA = new ExtrinsicEra({ current: currentHeight, period: 4 });
     const eraBirth = exERA.asMortalEra.birth(currentHeight.toNumber());
     const eraDeath = exERA.asMortalEra.death(currentHeight.toNumber());
-    console.log('STARTED AT :'+eraBirth+' EXPIRED AT :'+eraDeath);
+    console.log('STARTED AT :' + eraBirth + ' EXPIRED AT :' + eraDeath);
     const eraHash = await api.rpc.chain.getBlockHash(eraBirth);
     const ex = api.tx.balances.transfer(keyring.eve.address(), 12345);
-    const unsubscribe = await api.rpc.chain.subscribeNewHead(async(header) => {
-      console.log(`Chain is at block: #${header.blockNumber}`);
-      if (header.blockNumber.toNumber() === eraDeath-1) {
-        const hash = await ex.signAndSend(keyring.alice, {blockHash: eraHash, era:exERA, nonce});
 
-        expect(hash).toBeUndefined();
-        done();
-      }
-    });
+    return(
+      api.rpc.chain.subscribeNewHead(async (header) => {
+        if (header.blockNumber.toNumber() === eraDeath - 1) {
+          const hash = await ex.signAndSend(keyring.alice, { blockHash: eraHash, era: exERA, nonce } as any);
+
+          expect(hash).toBeUndefined();
+          done();
+        }
+      })
+    );
   });
 });
diff --git a/packages/api/test/e2e/rx-queries.spec.js b/packages/api/test/e2e/rx-queries.spec.ts
similarity index 78%
rename from packages/api/test/e2e/rx-queries.spec.js
rename to packages/api/test/e2e/rx-queries.spec.ts
index 1796f7a4a4..b0b39ba0f8 100644
--- a/packages/api/test/e2e/rx-queries.spec.js
+++ b/packages/api/test/e2e/rx-queries.spec.ts
@@ -2,14 +2,17 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import BN from 'bn.js';
 import { switchMap } from 'rxjs/operators';
+
+import { Balance } from '@polkadot/types';
 import testingPairs from '@polkadot/keyring/testingPairs';
 
 import Api from '../../src/rx';
 
-describe.skip('e2e queries', () => {
+describe.skip('Rx e2e queries', () => {
   const keyring = testingPairs({ type: 'ed25519' });
-  let api;
+  let api: Api;
 
   beforeEach(async (done) => {
     api = await Api.create().toPromise();
@@ -29,10 +32,8 @@ describe.skip('e2e queries', () => {
 
   it('queries state for a balance', (done) => {
     api.query.balances.freeBalance(keyring.alice.address()).subscribe((balance) => {
-      expect(
-        balance.isZero()
-      ).toBe(false);
-
+      expect(balance).toBeInstanceOf(BN);
+      expect((balance as Balance).isZero()).toBe(false);
       done();
     });
   });
@@ -41,11 +42,11 @@ describe.skip('e2e queries', () => {
     api.rpc.chain
       .getHeader()
       .pipe(
-        switchMap((header) =>
-          api.query.system.events.at(header.hash)
+        switchMap(({ hash }: any) =>
+          api.query.system.events.at(hash)
         )
       )
-      .subscribe((events) => {
+      .subscribe((events: any) => {
         expect(events.length).not.toEqual(0);
         done();
       });
diff --git a/packages/api/test/e2e/rx-tx.spec.js b/packages/api/test/e2e/rx-tx.spec.ts
similarity index 79%
rename from packages/api/test/e2e/rx-tx.spec.js
rename to packages/api/test/e2e/rx-tx.spec.ts
index 98957602f9..5de0263156 100644
--- a/packages/api/test/e2e/rx-tx.spec.js
+++ b/packages/api/test/e2e/rx-tx.spec.ts
@@ -3,18 +3,20 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { first, switchMap } from 'rxjs/operators';
+
 import testingPairs from '@polkadot/keyring/testingPairs';
 
-import Api from '../../src/rx';
+import Api from './../../src/rx';
+import { SubmittableResult } from './../../src';
 
-describe.skip('e2e transactions', () => {
+describe.skip('Rx e2e transactions', () => {
   const keyring = testingPairs({ type: 'ed25519' });
-  let api;
+  let api: Api;
 
   beforeEach(async (done) => {
     api = await Api.create().toPromise();
     jest.setTimeout(30000);
-    done()
+    done();
   });
 
   afterEach(() => {
@@ -26,14 +28,14 @@ describe.skip('e2e transactions', () => {
       .accountNonce(keyring.alice.address())
       .pipe(
         first(),
-        switchMap((nonce) =>
+        switchMap((nonce: any) =>
           api.tx.balances
             .transfer(keyring.bob.address(), 12345)
             .sign(keyring.alice, { nonce })
             .send()
         )
       )
-      .subscribe(({ status }) => {
+      .subscribe(({ status }: SubmittableResult) => {
         if (status.isFinalized) {
           done();
         }
@@ -45,14 +47,14 @@ describe.skip('e2e transactions', () => {
       .accountNonce(keyring.alice.address())
       .pipe(
         first(),
-        switchMap((nonce) =>
+        switchMap((nonce: any) =>
           api.tx.democracy
             .propose(api.tx.consensus.setCode('0xdeadbeef'), 10000)
             .sign(keyring.alice, { nonce })
             .send()
         )
       )
-      .subscribe(({ status }) => {
+      .subscribe(({ status }: SubmittableResult) => {
         if (status.isFinalized) {
           done();
         }
diff --git a/packages/rpc-core/src/formatting.spec.ts b/packages/rpc-core/src/formatting.spec.ts
index c24cc170b7..adaa2b3caf 100644
--- a/packages/rpc-core/src/formatting.spec.ts
+++ b/packages/rpc-core/src/formatting.spec.ts
@@ -3,6 +3,7 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import BN from 'bn.js';
+
 import fromMetadata from '@polkadot/storage/fromMetadata';
 import { Storage } from '@polkadot/storage/types';
 import Metadata from '@polkadot/types/Metadata';
diff --git a/packages/rpc-core/test/e2e/basics.test.js b/packages/rpc-core/test/e2e/basics.test.js
index 7b82880d51..9d14fd1e33 100644
--- a/packages/rpc-core/test/e2e/basics.test.js
+++ b/packages/rpc-core/test/e2e/basics.test.js
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Ws from '@polkadot/rpc-provider/ws';
+import WsProvider from '@polkadot/rpc-provider/ws';
 
 import Rpc from '../../src';
 
@@ -11,7 +11,7 @@ describe.skip('e2e basics', () => {
 
   beforeEach(() => {
     jest.setTimeout(30000);
-    api = new Rpc(new Ws('ws://127.0.0.1:9944'));
+    api = new Rpc(new WsProvider('ws://127.0.0.1:9944'));
   });
 
   it('retrieves the pending extrinsics', () => {
diff --git a/packages/rpc-core/test/e2e/chain.test.js b/packages/rpc-core/test/e2e/chain.test.js
index a40d734b18..14e9d7fa1f 100644
--- a/packages/rpc-core/test/e2e/chain.test.js
+++ b/packages/rpc-core/test/e2e/chain.test.js
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Ws from '@polkadot/rpc-provider/ws';
+import WsProvider from '@polkadot/rpc-provider/ws';
 
 import Rpc from '../../src';
 
@@ -11,7 +11,7 @@ describe.skip('e2e chain', () => {
 
   beforeEach(() => {
     jest.setTimeout(30000);
-    api = new Rpc(new Ws('ws://127.0.0.1:9944'));
+    api = new Rpc(new WsProvider('ws://127.0.0.1:9944'));
   });
 
   it('subscribes via subscribeNewHead', (done) => {
diff --git a/packages/rpc-core/test/e2e/krummelanke.test.js b/packages/rpc-core/test/e2e/krummelanke.test.js
index 6e48ad1182..66caeb96e2 100644
--- a/packages/rpc-core/test/e2e/krummelanke.test.js
+++ b/packages/rpc-core/test/e2e/krummelanke.test.js
@@ -3,7 +3,7 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import storage from '@polkadot/storage';
-import Ws from '@polkadot/rpc-provider/ws';
+import WsProvider from '@polkadot/rpc-provider/ws';
 
 import Rpc from '../../src';
 
@@ -12,7 +12,7 @@ describe.skip('e2e krumme lanke', () => {
 
   beforeEach(() => {
     jest.setTimeout(30000);
-    api = new Rpc(new Ws('ws://127.0.0.1:9944'));
+    api = new Rpc(new WsProvider('ws://127.0.0.1:9944'));
   });
 
   it('subscribes to storage', (done) => {
diff --git a/packages/rpc-core/test/e2e/state.test.js b/packages/rpc-core/test/e2e/state.test.js
index 4699540c3e..06e095f175 100644
--- a/packages/rpc-core/test/e2e/state.test.js
+++ b/packages/rpc-core/test/e2e/state.test.js
@@ -2,7 +2,6 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Ws from '@polkadot/rpc-provider/ws';
 import storage from '@polkadot/storage/static';
 
 import Rpc from '../../src';
@@ -14,7 +13,7 @@ describe.skip('e2e state', () => {
 
   beforeEach(() => {
     jest.setTimeout(30000);
-    api = new Rpc(new Ws('ws://127.0.0.1:9944'));
+    api = new Rpc(new WsProvider('ws://127.0.0.1:9944'));
   });
 
   it('retrieves code', () => {
diff --git a/packages/rpc-core/test/e2e/subscribe.test.js b/packages/rpc-core/test/e2e/subscribe.test.js
index da1da3d374..efbdfd21d9 100644
--- a/packages/rpc-core/test/e2e/subscribe.test.js
+++ b/packages/rpc-core/test/e2e/subscribe.test.js
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Ws from '@polkadot/rpc-provider/ws';
+import WsProvider from '@polkadot/rpc-provider/ws';
 import storage from '@polkadot/storage/static';
 
 import Rpc from '../../src';
@@ -12,7 +12,7 @@ describe.skip('e2e subscriptions', () => {
 
   beforeEach(() => {
     jest.setTimeout(30000);
-    api = new Rpc(new Ws('ws://127.0.0.1:9944'));
+    api = new Rpc(new WsProvider('ws://127.0.0.1:9944'));
   });
 
   it('retrieves current timestamp', (done) => {
diff --git a/packages/rpc-provider/src/coder/decodeResponse.spec.ts b/packages/rpc-provider/src/coder/decodeResponse.spec.ts
index 56b79c83b9..30e7d09b48 100644
--- a/packages/rpc-provider/src/coder/decodeResponse.spec.ts
+++ b/packages/rpc-provider/src/coder/decodeResponse.spec.ts
@@ -3,7 +3,7 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { JsonRpcResponse } from '../types';
-import Coder from '.';
+import Coder from './';
 
 describe('decodeResponse', () => {
   let coder: Coder;
diff --git a/packages/rpc-provider/src/coder/encodeJson.spec.ts b/packages/rpc-provider/src/coder/encodeJson.spec.ts
index b006fc77d4..ffdc5e76ff 100644
--- a/packages/rpc-provider/src/coder/encodeJson.spec.ts
+++ b/packages/rpc-provider/src/coder/encodeJson.spec.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Coder from '.';
+import Coder from './';
 
 describe('encodeJson', () => {
   let coder: Coder;
diff --git a/packages/rpc-provider/src/coder/encodeObject.spec.ts b/packages/rpc-provider/src/coder/encodeObject.spec.ts
index 8923071cb7..5d3b425560 100644
--- a/packages/rpc-provider/src/coder/encodeObject.spec.ts
+++ b/packages/rpc-provider/src/coder/encodeObject.spec.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Coder from '.';
+import Coder from './';
 
 describe('encodeObject', () => {
   let coder: Coder;
diff --git a/packages/rpc-provider/src/http/index.spec.js b/packages/rpc-provider/src/http/index.spec.ts
similarity index 82%
rename from packages/rpc-provider/src/http/index.spec.js
rename to packages/rpc-provider/src/http/index.spec.ts
index 2ce7c922c7..78fd4bb090 100644
--- a/packages/rpc-provider/src/http/index.spec.js
+++ b/packages/rpc-provider/src/http/index.spec.ts
@@ -3,11 +3,10 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { TEST_HTTP_URL } from '../../test/mockHttp';
-
-import Http from '.';
+import Http from './';
 
 describe('Http', () => {
-  let http;
+  let http: Http;
 
   beforeEach(() => {
     http = new Http(TEST_HTTP_URL);
@@ -30,13 +29,13 @@ describe('Http', () => {
   });
 
   it('does not (yet) support subscribe', () => {
-    return http.subscribe().catch((error) => {
+    return http.subscribe('', '', [], (cb) => { expect(cb).toEqual(expect.anything()); }).catch((error) => {
       expect(error.message).toMatch(/does not have subscriptions/);
     });
   });
 
   it('does not (yet) support unsubscribe', () => {
-    return http.unsubscribe().catch((error) => {
+    return http.unsubscribe('', '', 0).catch((error) => {
       expect(error.message).toMatch(/does not have subscriptions/);
     });
   });
diff --git a/packages/rpc-provider/src/http/polyfill.spec.js b/packages/rpc-provider/src/http/polyfill.spec.ts
similarity index 60%
rename from packages/rpc-provider/src/http/polyfill.spec.js
rename to packages/rpc-provider/src/http/polyfill.spec.ts
index fc7ae18b8b..da4c254cfc 100644
--- a/packages/rpc-provider/src/http/polyfill.spec.js
+++ b/packages/rpc-provider/src/http/polyfill.spec.ts
@@ -2,12 +2,15 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Global } from './../mock/types';
+
+declare const global: Global;
+
 describe('http/polyfill', () => {
-  let origFetch;
+  let origFetch: GlobalFetch;
 
   beforeEach(() => {
     origFetch = global.fetch;
-    global.fetch = null;
   });
 
   afterEach(() => {
@@ -15,12 +18,16 @@ describe('http/polyfill', () => {
   });
 
   it('polyfills with no exceptions (without fetch)', () => {
-    expect(require('./polyfill')).toBeDefined();
+    (global as any).fetch = undefined;
+    require('./polyfill');
+
+    expect(global.fetch).toBeDefined();
   });
 
   it('polyfills with no exceptions (with fetch)', () => {
-    global.fetch = () => true;
+    (global as any).fetch = () => true;
+    require('./polyfill');
 
-    expect(require('./polyfill')).toBeDefined();
+    expect(global.fetch).toBeDefined();
   });
 });
diff --git a/packages/rpc-provider/src/http/send.spec.js b/packages/rpc-provider/src/http/send.spec.ts
similarity index 87%
rename from packages/rpc-provider/src/http/send.spec.js
rename to packages/rpc-provider/src/http/send.spec.ts
index eb3424a933..985b955e55 100644
--- a/packages/rpc-provider/src/http/send.spec.js
+++ b/packages/rpc-provider/src/http/send.spec.ts
@@ -2,13 +2,13 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import Http from './';
+import { Mock } from './../mock/types';
 import { mockHttp, TEST_HTTP_URL } from '../../test/mockHttp';
 
-import Http from '.';
-
 describe('send', () => {
-  let http;
-  let mock;
+  let http: Http;
+  let mock: Mock;
 
   beforeEach(() => {
     http = new Http(TEST_HTTP_URL);
@@ -17,7 +17,6 @@ describe('send', () => {
   afterEach(() => {
     if (mock) {
       mock.done();
-      mock = null;
     }
   });
 
@@ -32,7 +31,7 @@ describe('send', () => {
     return http
       .send('test_body', ['param'])
       .then((result) => {
-        expect(mock.body['test_body']).toEqual({
+        expect((mock.body as any)['test_body']).toEqual({
           id: 1,
           jsonrpc: '2.0',
           method: 'test_body',
diff --git a/packages/rpc-provider/src/mock/on.spec.ts b/packages/rpc-provider/src/mock/on.spec.ts
index f5143d2511..c33ef5d1e9 100644
--- a/packages/rpc-provider/src/mock/on.spec.ts
+++ b/packages/rpc-provider/src/mock/on.spec.ts
@@ -4,7 +4,7 @@
 
 import { ProviderInterface$Emitted } from '../types';
 
-import Mock from '.';
+import Mock from './';
 
 describe('on', () => {
   let mock: Mock;
diff --git a/packages/rpc-provider/src/mock/send.spec.ts b/packages/rpc-provider/src/mock/send.spec.ts
index c684d18168..e720cb2ab8 100644
--- a/packages/rpc-provider/src/mock/send.spec.ts
+++ b/packages/rpc-provider/src/mock/send.spec.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Mock from '.';
+import Mock from './';
 
 describe('send', () => {
   let mock: Mock;
diff --git a/packages/rpc-provider/src/mock/subscribe.spec.ts b/packages/rpc-provider/src/mock/subscribe.spec.ts
index 3d298abbcc..dce16250da 100644
--- a/packages/rpc-provider/src/mock/subscribe.spec.ts
+++ b/packages/rpc-provider/src/mock/subscribe.spec.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Mock from '.';
+import Mock from './';
 
 describe('subscribe', () => {
   let mock: Mock;
diff --git a/packages/rpc-provider/src/mock/types.ts b/packages/rpc-provider/src/mock/types.ts
index 7ddd7b1eba..ff8ba7d9fb 100644
--- a/packages/rpc-provider/src/mock/types.ts
+++ b/packages/rpc-provider/src/mock/types.ts
@@ -2,6 +2,21 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Server } from 'mock-socket';
+import { Constructor } from '@polkadot/types/types';
+
+export interface Global extends NodeJS.Global {
+  WebSocket: Constructor<WebSocket>;
+  fetch: GlobalFetch;
+}
+
+export type Mock = {
+  body: Object,
+  requests: Number,
+  server: Server
+  done: () => {}
+};
+
 export type MockState$Subscription$Callback = (error: Error | null, value: any) => void;
 
 export type MockState$Subscriptions = {
diff --git a/packages/rpc-provider/src/mock/unsubscribe.spec.ts b/packages/rpc-provider/src/mock/unsubscribe.spec.ts
index cdceda9db0..e38091da1f 100644
--- a/packages/rpc-provider/src/mock/unsubscribe.spec.ts
+++ b/packages/rpc-provider/src/mock/unsubscribe.spec.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Mock from '.';
+import Mock from './';
 
 describe('unsubscribe', () => {
   let mock: Mock;
diff --git a/packages/rpc-provider/src/ws/Provider.ts b/packages/rpc-provider/src/ws/Provider.ts
index ab161dbef9..6c577a3b21 100644
--- a/packages/rpc-provider/src/ws/Provider.ts
+++ b/packages/rpc-provider/src/ws/Provider.ts
@@ -176,7 +176,7 @@ export default class WsProvider implements WSProviderInterface {
    * @param params Encoded paramaters as appliucable for the method
    * @param subscription Subscription details (internally used)
    */
-  async send (method: string, params: Array<any>, subscription?: SubscriptionHandler): Promise<any> {
+  send (method: string, params: Array<any>, subscription?: SubscriptionHandler): Promise<any> {
     return new Promise((resolve, reject): void => {
       try {
         const json = this.coder.encodeJson(method, params);
diff --git a/packages/rpc-provider/src/ws/connect.spec.js b/packages/rpc-provider/src/ws/connect.spec.js
deleted file mode 100644
index 6a6f0aff9f..0000000000
--- a/packages/rpc-provider/src/ws/connect.spec.js
+++ /dev/null
@@ -1,33 +0,0 @@
-// Copyright 2017-2019 @polkadot/rpc-provider authors & contributors
-// This software may be modified and distributed under the terms
-// of the Apache-2.0 license. See the LICENSE file for details.
-
-import { mockWs, TEST_WS_URL } from '../../test/mockWs';
-
-import Ws from '.';
-
-describe('onConnect', () => {
-  let mock;
-
-  beforeEach(() => {
-    mock = mockWs([]);
-  });
-
-  afterEach(() => {
-    if (mock) {
-      mock.done();
-      mock = null;
-    }
-  });
-
-  it('sets up the on* handlers', () => {
-    const ws = new Ws(TEST_WS_URL, false);
-
-    ws.connect();
-
-    expect(ws.websocket.onclose[0]).toBeDefined();
-    expect(ws.websocket.onerror[0]).toBeDefined();
-    expect(ws.websocket.onmessage[0]).toBeDefined();
-    expect(ws.websocket.onopen[0]).toBeDefined();
-  });
-});
diff --git a/packages/rpc-provider/src/ws/connect.spec.ts b/packages/rpc-provider/src/ws/connect.spec.ts
new file mode 100644
index 0000000000..cb475b7026
--- /dev/null
+++ b/packages/rpc-provider/src/ws/connect.spec.ts
@@ -0,0 +1,63 @@
+// Copyright 2017-2019 @polkadot/rpc-provider authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import WsProvider from './';
+import { Mock } from './../mock/types';
+import { mockWs, TEST_WS_URL } from '../../test/mockWs';
+
+describe('onConnect', () => {
+  let mock: Mock;
+
+  beforeEach(() => {
+    mock = mockWs([]);
+  });
+
+  afterEach(() => {
+    if (mock) {
+      mock.done();
+    }
+  });
+
+  it('Does not connect when autoConnect is false', () => {
+    const provider: WsProvider = new WsProvider(TEST_WS_URL, false);
+    // We need to access the private WsProvider property 'websocket' here which would otherwise trigger a tslint error.
+    // @ts-ignore
+    expect(provider.websocket).toBeNull();
+  });
+
+  it('Does connect when autoConnect is true', () => {
+    const provider: WsProvider = new WsProvider(TEST_WS_URL, true);
+    // @ts-ignore
+    expect(provider.websocket).not.toBeNull();
+  });
+
+  it('Creates a new WebSocket instance by calling the connect() method', () => {
+    const provider: WsProvider = new WsProvider(TEST_WS_URL, false);
+    // @ts-ignore
+    expect(provider.websocket).toBeNull();
+
+    provider.connect();
+
+    // @ts-ignore
+    expect(provider.websocket).not.toBeNull();
+    // @ts-ignore
+    expect(provider.websocket instanceof WebSocket).toBe(true);
+  });
+
+  it('Creates the on handlers', () => {
+    const provider: WsProvider = new WsProvider(TEST_WS_URL);
+
+    // @ts-ignore
+    expect(provider.websocket).not.toBeNull();
+    // @ts-ignore
+    expect(provider.websocket).toEqual(expect.objectContaining({
+      listeners: expect.objectContaining({
+        close: [expect.any(Function)],
+        error: [expect.any(Function)],
+        message: [expect.any(Function)],
+        open: [expect.any(Function)]
+      })
+    }));
+  });
+});
diff --git a/packages/rpc-provider/src/ws/index.spec.js b/packages/rpc-provider/src/ws/index.spec.ts
similarity index 64%
rename from packages/rpc-provider/src/ws/index.spec.js
rename to packages/rpc-provider/src/ws/index.spec.ts
index 480ca11a2e..bbce3058f1 100644
--- a/packages/rpc-provider/src/ws/index.spec.js
+++ b/packages/rpc-provider/src/ws/index.spec.ts
@@ -2,17 +2,16 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import WsProvider from './';
+import { Mock } from './../mock/types';
 import { mockWs, TEST_WS_URL } from '../../test/mockWs';
 
-import Ws from '.';
+let ws: WsProvider;
+let mock: Mock;
 
-let ws;
-let mock;
-
-function createWs (requests, autoConnect) {
+function createWs (requests: Array<any>, autoConnect: boolean | undefined) {
   mock = mockWs(requests);
-  ws = new Ws(TEST_WS_URL, autoConnect);
-
+  ws = new WsProvider(TEST_WS_URL, autoConnect);
   return ws;
 }
 
@@ -20,13 +19,12 @@ describe('Ws', () => {
   afterEach(() => {
     if (mock) {
       mock.done();
-      mock = null;
     }
   });
 
   it('returns the connected state', () => {
     expect(
-      createWs([]).isConnected()
+      createWs([],true).isConnected()
     ).toEqual(false);
   });
 });
diff --git a/packages/rpc-provider/src/ws/onMessageResult.spec.js b/packages/rpc-provider/src/ws/onMessageResult.spec.js
deleted file mode 100644
index e3b5a09d12..0000000000
--- a/packages/rpc-provider/src/ws/onMessageResult.spec.js
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright 2017-2019 @polkadot/rpc-provider authors & contributors
-// This software may be modified and distributed under the terms
-// of the Apache-2.0 license. See the LICENSE file for details.
-
-import Ws from '.';
-
-describe('onMessageResult', () => {
-  let ws;
-
-  beforeEach(() => {
-    ws = new Ws('ws://127.0.0.1:1234', false);
-  });
-
-  it('calls the handler when found', (done) => {
-    ws.handlers[5] = {
-      callback: (_, result) => {
-        expect(result).toEqual('test');
-        done();
-      }
-    };
-
-    ws.onSocketMessage({ data: '{"jsonrpc":"2.0","id":5,"result":"test"}' });
-  });
-});
diff --git a/packages/rpc-provider/src/ws/onMessageResult.spec.ts b/packages/rpc-provider/src/ws/onMessageResult.spec.ts
new file mode 100644
index 0000000000..ecf7bc7be3
--- /dev/null
+++ b/packages/rpc-provider/src/ws/onMessageResult.spec.ts
@@ -0,0 +1,30 @@
+// Copyright 2017-2019 @polkadot/rpc-provider authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import WsProvider from './';
+
+describe('WsProvider', () => {
+  let provider: WsProvider;
+
+  beforeEach(() => {
+    provider = new WsProvider('ws://127.0.0.1:1234', false);
+  });
+
+  it('calls the handler when found', (done) => {
+    // We need to access the private WsProvider property 'handlers' here which otherwise trigger a tslint error..
+    // @ts-ignore
+    provider.handlers[5] = {
+      callback: (_: any, result: any) => {
+        expect(result).toEqual('test');
+        done();
+      },
+      method: '',
+      params: []
+    };
+
+    // We need to access the private WsProvider property 'onSocketMessage' here which would otherwise trigger a tslint error.
+    // @ts-ignore
+    provider.onSocketMessage(new MessageEvent('test', { data: '{"jsonrpc":"2.0","id":5,"result":"test"}' }));
+  });
+});
diff --git a/packages/rpc-provider/src/ws/onMessageSubscribe.spec.js b/packages/rpc-provider/src/ws/onMessageSubscribe.spec.js
deleted file mode 100644
index 0f139b1d02..0000000000
--- a/packages/rpc-provider/src/ws/onMessageSubscribe.spec.js
+++ /dev/null
@@ -1,47 +0,0 @@
-// Copyright 2017-2019 @polkadot/rpc-provider authors & contributors
-// This software may be modified and distributed under the terms
-// of the Apache-2.0 license. See the LICENSE file for details.
-
-import Ws from '.';
-
-describe('onMessageSubscribe', () => {
-  let ws;
-
-  beforeEach(() => {
-    ws = new Ws('ws://127.0.0.1:1234', false);
-  });
-
-  it('calls the subscriber with data', (done) => {
-    ws.handlers[11] = {
-      callback: (_, id) => {},
-      method: 'test',
-      subscription: {
-        callback: (_, result) => {
-          expect(result).toEqual('test');
-          done();
-        },
-        type: 'test'
-      }
-    };
-
-    ws.onSocketMessage({ data: '{"jsonrpc":"2.0","id":11,"result":22}' });
-    ws.onSocketMessage({ data: '{"jsonrpc":"2.0","method":"test","params":{"subscription":22,"result":"test"}}' });
-  });
-
-  it('calls the subscriber with error', (done) => {
-    ws.handlers[11] = {
-      callback: (_, id) => {},
-      method: 'test',
-      subscription: {
-        callback: (error) => {
-          expect(error.message).toMatch(/test/);
-          done();
-        },
-        type: 'test'
-      }
-    };
-
-    ws.onSocketMessage({ data: '{"jsonrpc":"2.0","id":11,"result":22}' });
-    ws.onSocketMessage({ data: '{"jsonrpc":"2.0","method":"test","params":{"subscription":22,"error":{"message":"test"}}}' });
-  });
-});
diff --git a/packages/rpc-provider/src/ws/onMessageSubscribe.spec.ts b/packages/rpc-provider/src/ws/onMessageSubscribe.spec.ts
new file mode 100644
index 0000000000..1c9ecb45e8
--- /dev/null
+++ b/packages/rpc-provider/src/ws/onMessageSubscribe.spec.ts
@@ -0,0 +1,63 @@
+// Copyright 2017-2019 @polkadot/rpc-provider authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import WsProvider from './';
+
+describe('onMessageSubscribe', () => {
+  let provider: WsProvider;
+
+  beforeEach(() => {
+    provider = new WsProvider('ws://127.0.0.1:1234', false);
+  });
+
+  it('calls the subscriber with data', (done) => {
+    // We need to access the private WsProvider property 'handlers' here which otherwise triggers a tslint error..
+    // @ts-ignore
+    provider.handlers[11] = {
+      callback: (_: any, id: number) => {
+        expect(typeof id).toBe('number');
+      },
+      method: 'test',
+      params: [],
+      subscription: {
+        callback: (_: any, result: any) => {
+          expect(result).toEqual('test');
+          done();
+        },
+        type: 'test'
+      }
+    };
+
+    // We need to access the private WsProvider property 'onSocketMessage' here which would otherwise trigger a tslint error.
+    // @ts-ignore
+    provider.onSocketMessage(new MessageEvent('test', { data: '{"jsonrpc":"2.0","id":11,"result":22}' }));
+    // @ts-ignore
+    provider.onSocketMessage(new MessageEvent('test', { data: '{"jsonrpc":"2.0","method":"test","params":{"subscription":22,"result":"test"}}' }));
+  });
+
+  it('calls the subscriber with error', (done) => {
+    // We need to access the private WsProvider property 'handlers' here which otherwise trigger a tslint error..
+    // @ts-ignore
+    provider.handlers[11] = {
+      callback: (_: any, id: number) => {
+        expect(typeof id).toBe('number');
+      },
+      method: 'test',
+      params: [],
+      subscription: {
+        callback: (error: any) => {
+          expect(error.message).toMatch(/test/);
+          done();
+        },
+        type: 'test'
+      }
+    };
+
+    // We need to access the private WsProvider property 'onSocketMessage' here which would otherwise trigger a tslint error.
+    // @ts-ignore
+    provider.onSocketMessage(new MessageEvent('test', { data: '{"jsonrpc":"2.0","id":11,"result":22}' }));
+    // @ts-ignore
+    provider.onSocketMessage(new MessageEvent('test', { data: '{"jsonrpc":"2.0","method":"test","params":{"subscription":22,"error":{"message":"test"}}}' }));
+  });
+});
diff --git a/packages/rpc-provider/src/ws/onOpen.spec.js b/packages/rpc-provider/src/ws/onOpen.spec.ts
similarity index 76%
rename from packages/rpc-provider/src/ws/onOpen.spec.js
rename to packages/rpc-provider/src/ws/onOpen.spec.ts
index 4615711443..f156ece373 100644
--- a/packages/rpc-provider/src/ws/onOpen.spec.js
+++ b/packages/rpc-provider/src/ws/onOpen.spec.ts
@@ -2,16 +2,16 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import WsProvider from './';
+import { Mock } from './../mock/types';
 import { mockWs, TEST_WS_URL } from '../../test/mockWs';
 
-import Ws from '.';
+let ws: WsProvider;
+let mock: Mock;
 
-let ws;
-let mock;
-
-function createWs (requests, autoConnect) {
+function createWs (requests: Array<any>, autoConnect: boolean | undefined) {
   mock = mockWs(requests);
-  ws = new Ws(TEST_WS_URL, autoConnect);
+  ws = new WsProvider(TEST_WS_URL, autoConnect);
 
   return ws;
 }
@@ -20,7 +20,6 @@ describe('onOpen', () => {
   afterEach(() => {
     if (mock) {
       mock.done();
-      mock = null;
     }
   });
 
diff --git a/packages/rpc-provider/src/ws/polyfill.spec.js b/packages/rpc-provider/src/ws/polyfill.spec.ts
similarity index 55%
rename from packages/rpc-provider/src/ws/polyfill.spec.js
rename to packages/rpc-provider/src/ws/polyfill.spec.ts
index d9695a0b28..ac246bdfce 100644
--- a/packages/rpc-provider/src/ws/polyfill.spec.js
+++ b/packages/rpc-provider/src/ws/polyfill.spec.ts
@@ -2,25 +2,34 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Constructor } from '@polkadot/types/types';
+
+import { Global } from './../mock/types';
+
+declare let global: Global;
+
 describe('ws/polyfill', () => {
-  let origWs;
+  let origWs: Constructor<WebSocket>;
 
   beforeEach(() => {
     origWs = global.WebSocket;
-    global.WebSocket = null;
   });
 
   afterEach(() => {
     global.WebSocket = origWs;
   });
 
-  it('polyfills with no exceptions (without WebSocket)', () => {
-    expect(require('./polyfill')).toBeDefined();
+  it('polyfills with no exceptions (with WebSocket)', () => {
+    (global as any).WebSocket = undefined;
+    require('./polyfill');
+
+    expect(global.WebSocket).toBeDefined();
   });
 
-  it('polyfills with no exceptions (with WebSocket)', () => {
-    global.WebSocket = () => true;
+  it('polyfills with no exceptions (without WebSocket)', () => {
+    (global as any).WebSocket = () => true;
+    require('./polyfill');
 
-    expect(require('./polyfill')).toBeDefined();
+    expect(global.WebSocket).toBeDefined();
   });
 });
diff --git a/packages/rpc-provider/src/ws/send.spec.js b/packages/rpc-provider/src/ws/send.spec.ts
similarity index 68%
rename from packages/rpc-provider/src/ws/send.spec.js
rename to packages/rpc-provider/src/ws/send.spec.ts
index 94149065ed..ee18724118 100644
--- a/packages/rpc-provider/src/ws/send.spec.js
+++ b/packages/rpc-provider/src/ws/send.spec.ts
@@ -2,25 +2,28 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Constructor } from '@polkadot/types/types';
+
+import WsProvider from './';
+import { Global, Mock } from './../mock/types';
 import { mockWs, TEST_WS_URL } from '../../test/mockWs';
 
-import Ws from '.';
+declare const global: Global;
+let provider: WsProvider;
+let mock: Mock;
 
-let ws;
-let mock;
-
-function createMock (requests) {
+function createMock (requests: Array<any>) {
   mock = mockWs(requests);
 }
 
-function createWs (autoConnect) {
-  ws = new Ws(TEST_WS_URL, autoConnect);
+function createWs (autoConnect: boolean = true) {
+  provider = new WsProvider(TEST_WS_URL, autoConnect);
 
-  return ws;
+  return provider;
 }
 
 describe('send', () => {
-  let globalWs;
+  let globalWs: Constructor<WebSocket>;
 
   beforeEach(() => {
     globalWs = global.WebSocket;
@@ -31,29 +34,23 @@ describe('send', () => {
 
     if (mock) {
       mock.done();
-      mock = null;
     }
   });
 
   it('handles internal errors', () => {
     createMock([]);
 
-    let websocket;
-
-    global.WebSocket = class {
-      constructor () {
-        websocket = this;
-      }
-
+    (global as any).WebSocket = class {
       send () {
         throw new Error('send error');
       }
     };
 
-    ws = createWs();
-    websocket.onopen();
+    provider = createWs(true);
+    // @ts-ignore Accessing private method
+    provider.websocket.onopen();
 
-    return ws
+    return provider
       .send('test_encoding', ['param'])
       .catch((error) => {
         expect(error.message).toEqual('send error');
@@ -69,11 +66,11 @@ describe('send', () => {
       }
     }]);
 
-    return createWs()
+    return createWs(true)
       .send('test_body', ['param'])
       .then((result) => {
         expect(
-          mock.body['test_body']
+          (mock.body as any)['test_body']
         ).toEqual('{"id":1,"jsonrpc":"2.0","method":"test_body","params":["param"]}');
       });
   });
@@ -87,7 +84,7 @@ describe('send', () => {
       }
     }]);
 
-    return createWs()
+    return createWs(true)
       .send('test_error', [])
       .catch((error) => {
         expect(error.message).toMatch(/666: error/);
@@ -103,8 +100,8 @@ describe('send', () => {
       }
     }]);
 
-    return createWs()
-      .send('test_sub', [], () => {})
+    return createWs(true)
+      .send('test_sub', [])
       .then((id) => {
         expect(id).toEqual(1);
       });
diff --git a/packages/rpc-provider/src/ws/state.spec.js b/packages/rpc-provider/src/ws/state.spec.ts
similarity index 77%
rename from packages/rpc-provider/src/ws/state.spec.js
rename to packages/rpc-provider/src/ws/state.spec.ts
index b47418acc4..3ddf75eea1 100644
--- a/packages/rpc-provider/src/ws/state.spec.js
+++ b/packages/rpc-provider/src/ws/state.spec.ts
@@ -2,18 +2,18 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Ws from '.';
+import WsProvider from './';
 
 describe('state', () => {
   it('requires an ws:// prefixed endpoint', () => {
     expect(
-      () => new Ws('http://', false)
+      () => new WsProvider('http://', false)
     ).toThrow(/with 'ws/);
   });
 
   it('allows wss:// endpoints', () => {
     expect(
-      () => new Ws('wss://', false)
+      () => new WsProvider('wss://', false)
     ).not.toThrow();
   });
 });
diff --git a/packages/rpc-provider/src/ws/subscribe.spec.js b/packages/rpc-provider/src/ws/subscribe.spec.ts
similarity index 59%
rename from packages/rpc-provider/src/ws/subscribe.spec.js
rename to packages/rpc-provider/src/ws/subscribe.spec.ts
index 02ba4fb97e..846354cae8 100644
--- a/packages/rpc-provider/src/ws/subscribe.spec.js
+++ b/packages/rpc-provider/src/ws/subscribe.spec.ts
@@ -2,25 +2,28 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Constructor } from '@polkadot/types/types';
+
+import WsProvider from './';
+import { Global, Mock } from './../mock/types';
 import { mockWs, TEST_WS_URL } from '../../test/mockWs';
 
-import Ws from '.';
+declare var global: Global;
+let ws: WsProvider;
+let mock: Mock;
 
-let ws;
-let mock;
-
-function createMock (requests) {
+function createMock (requests: Array<any>) {
   mock = mockWs(requests);
 }
 
-function createWs (autoConnect) {
-  ws = new Ws(TEST_WS_URL, autoConnect);
+function createWs (autoConnect: boolean = true) {
+  ws = new WsProvider(TEST_WS_URL, autoConnect);
 
   return ws;
 }
 
 describe('subscribe', () => {
-  let globalWs;
+  let globalWs: Constructor<WebSocket>;
 
   beforeEach(() => {
     globalWs = global.WebSocket;
@@ -31,7 +34,6 @@ describe('subscribe', () => {
 
     if (mock) {
       mock.done();
-      mock = null;
     }
   });
 
@@ -44,8 +46,8 @@ describe('subscribe', () => {
       }
     }]);
 
-    return createWs()
-      .subscribe('test_sub', [], () => {})
+    return createWs(true)
+      .subscribe('type', 'test_sub', [], (cb) => { expect(cb).toEqual(expect.anything()); })
       .then((id) => {
         expect(id).toEqual(1);
       });
diff --git a/packages/rpc-provider/src/ws/unsubscribe.spec.js b/packages/rpc-provider/src/ws/unsubscribe.spec.ts
similarity index 66%
rename from packages/rpc-provider/src/ws/unsubscribe.spec.js
rename to packages/rpc-provider/src/ws/unsubscribe.spec.ts
index e307beeea2..997d72682b 100644
--- a/packages/rpc-provider/src/ws/unsubscribe.spec.js
+++ b/packages/rpc-provider/src/ws/unsubscribe.spec.ts
@@ -2,25 +2,28 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { Constructor } from '@polkadot/types/types';
+
+import WsProvider from './';
+import { Global, Mock } from './../mock/types';
 import { mockWs, TEST_WS_URL } from '../../test/mockWs';
 
-import Ws from '.';
+declare var global: Global;
+let ws: WsProvider;
+let mock: Mock;
 
-let ws;
-let mock;
-
-function createMock (requests) {
+function createMock (requests: any) {
   mock = mockWs(requests);
 }
 
-function createWs (autoConnect) {
-  ws = new Ws(TEST_WS_URL, autoConnect);
+function createWs (autoConnect: boolean = true) {
+  ws = new WsProvider(TEST_WS_URL, autoConnect);
 
   return ws;
 }
 
 describe('subscribe', () => {
-  let globalWs;
+  let globalWs: Constructor<WebSocket>;
 
   beforeEach(() => {
     globalWs = global.WebSocket;
@@ -31,7 +34,6 @@ describe('subscribe', () => {
 
     if (mock) {
       mock.done();
-      mock = null;
     }
   });
 
@@ -53,10 +55,10 @@ describe('subscribe', () => {
       }
     ]);
 
-    const ws = createWs();
+    const ws = createWs(true);
 
     return ws
-      .subscribe('test', 'subscribe_test', [], () => {})
+      .subscribe('test', 'subscribe_test', [], (cb) => { expect(cb).toEqual(expect.anything()); })
       .then((id) => {
         return ws.unsubscribe('test', 'subscribe_test', id);
       });
@@ -71,10 +73,10 @@ describe('subscribe', () => {
       }
     }]);
 
-    const ws = createWs();
+    const ws = createWs(true);
 
     return ws
-      .subscribe('test', 'subscribe_test', [], () => {})
+      .subscribe('test', 'subscribe_test', [], (cb) => { expect(cb).toEqual(expect.anything()); })
       .then((id) => {
         return ws.unsubscribe('test', 'subscribe_test', 111);
       })
diff --git a/packages/rpc-provider/test/mockWs.ts b/packages/rpc-provider/test/mockWs.ts
index 5d80dd5605..3fa5abf84b 100644
--- a/packages/rpc-provider/test/mockWs.ts
+++ b/packages/rpc-provider/test/mockWs.ts
@@ -46,11 +46,12 @@ function mockWs (requests: Array<{ method: string }>) {
   server = new Server(TEST_WS_URL);
 
   let requestCount = 0;
-  const scope: { body: { [index: string]: {} }, requests: number, server: Server, done: any } = {
-    body: {},
-    requests: 0,
-    server,
-    done: () =>
+  const scope: {
+    body: { [index: string]: {} },
+    requests: number,
+    server: Server,
+    done: any
+  } = { body: {}, requests: 0, server, done: () =>
       server.stop(() => {
         // ignore
       })
@@ -58,7 +59,7 @@ function mockWs (requests: Array<{ method: string }>) {
 
   server.on('connection', (socket) => {
     // @ts-ignore definitions are wrong, this is 'on', not 'onmessage'
-    socket.on('message', (body: {}) => {
+    socket.on('message', (body: { [index: string]: {} }) => {
       const request = requests[requestCount];
       // @ts-ignore Yes, SHOULD be fixed, this is a mess
       const response = request.error
diff --git a/packages/rpc-rx/src/cached.spec.ts b/packages/rpc-rx/src/cached.spec.ts
index 551527cf28..7fa174c404 100644
--- a/packages/rpc-rx/src/cached.spec.ts
+++ b/packages/rpc-rx/src/cached.spec.ts
@@ -3,6 +3,7 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { Observable } from 'rxjs';
+
 import testingPairs from '@polkadot/keyring/testingPairs';
 import { RpcInterface$Section } from '@polkadot/rpc-core/types';
 import { AccountId } from '@polkadot/types';
diff --git a/packages/rpc-rx/src/replay.spec.ts b/packages/rpc-rx/src/replay.spec.ts
index 6b74e32ab0..2567dad81c 100644
--- a/packages/rpc-rx/src/replay.spec.ts
+++ b/packages/rpc-rx/src/replay.spec.ts
@@ -3,6 +3,7 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { Observable } from 'rxjs';
+
 import { RpcInterface$Section } from '@polkadot/rpc-core/types';
 
 jest.mock('@polkadot/rpc-provider/ws', () => class {
diff --git a/packages/rpc-rx/test/e2e/subscribe.test.js b/packages/rpc-rx/test/e2e/subscribe.test.js
index abb0a8fdb5..6d438fdb2d 100644
--- a/packages/rpc-rx/test/e2e/subscribe.test.js
+++ b/packages/rpc-rx/test/e2e/subscribe.test.js
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import Ws from '@polkadot/rpc-provider/ws';
+import WsProvider from '@polkadot/rpc-provider/ws';
 import storage from '@polkadot/storage/static';
 
 import RpcRx from '../../src';
@@ -13,7 +13,7 @@ describe.skip('e2e subscriptions', () => {
   beforeEach(() => {
     jest.setTimeout(30000);
 
-    api = new RpcRx(new Ws('ws://127.0.0.1:9944'));
+    api = new RpcRx(new WsProvider('ws://127.0.0.1:9944'));
   });
 
   it('retrieves current timestamp', (done) => {
diff --git a/packages/type-extrinsics/test/e2e/transfer.spec.js b/packages/type-extrinsics/test/e2e/transfer.spec.ts
similarity index 65%
rename from packages/type-extrinsics/test/e2e/transfer.spec.js
rename to packages/type-extrinsics/test/e2e/transfer.spec.ts
index ccc456f208..08a652f79d 100644
--- a/packages/type-extrinsics/test/e2e/transfer.spec.js
+++ b/packages/type-extrinsics/test/e2e/transfer.spec.ts
@@ -2,57 +2,59 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
+import { RpcInterface } from '@polkadot/rpc-core/types';
+import { SubmittableResult } from '@polkadot/api/SubmittableExtrinsic';
 import Rpc from '@polkadot/rpc-core';
-import Ws from '@polkadot/rpc-provider/ws';
+import WsProvider from '@polkadot/rpc-provider/ws';
 import testingPairs from '@polkadot/keyring/testingPairs';
 
-import extrinsics from '../../src/static';
+import extrinsics from './../../src/static';
 
 const keyring = testingPairs({ type: 'ed25519' });
 
+// @TODO 1: All three tests below are broken, fix or find better way to test transfers.
+// @TODO 2: Move tests out of ./type-extrinsics to ./api folder
 describe.skip('e2e transfer', () => {
-  let api;
+  let api: RpcInterface;
 
   beforeAll(() => {
-    api = new Rpc(new Ws('ws://127.0.0.1:9944'));
+    api = new Rpc(new WsProvider('ws://127.0.0.1:9944'));
+  });
+
+  beforeEach(() => {
+    jest.setTimeout(30000);
   });
 
   // Error: [1002]: Inherent transactions cannot be queued.
-  it.skip('inherent test', () => {
+  it('inherent test', () => {
     const inherent = extrinsics.timestamp.set(Math.round(Date.now() / 1000));
 
     return api.author.submitExtrinsic(inherent.toU8a()).then(console.log);
   });
 
-  it.skip('makes a transfer for a transaction', () => {
+  it('makes a transfer for a transaction', () => {
     return api.chain
       .getBlockHash(0)
       .then((genesisHash) => {
-        const extrinsic = extrinsics.balances.transfer(keyring.bob.publicKey(), 6969);
-
+        const extrinsic = extrinsics.balances.transfer(keyring.bob.publicKey(), 6969) as any;
         extrinsic.sign(keyring.alice, { blockHash: genesisHash, nonce: 0 });
 
         return api.author.submitExtrinsic(extrinsic.toU8a());
-      })
-      .then(console.log);
+      });
   });
 
   it('makes a transfer via watch', (done) => {
     return api.chain
       .getBlockHash(0)
       .then((genesisHash) => {
-        const extrinsic = extrinsics.balances.transfer(keyring.bob.publicKey(), 6969);
-
+        const extrinsic = extrinsics.balances.transfer(keyring.bob.publicKey(), 6969) as any;
         extrinsic.sign(keyring.alice, { blockHash: genesisHash, nonce: 0 });
 
-        return api.author.submitAndWatchExtrinsic(extrinsic, (result) => {
-          console.log(result);
-
+        return api.author.submitAndWatchExtrinsic(extrinsic, (result: SubmittableResult) => {
           if (result.status.isFinalized) {
             done();
           }
         });
-      })
-      .then(console.log);
+      });
   });
 });
diff --git a/packages/type-jsonrpc/src/index.spec.js b/packages/type-jsonrpc/src/index.spec.ts
similarity index 92%
rename from packages/type-jsonrpc/src/index.spec.js
rename to packages/type-jsonrpc/src/index.spec.ts
index 3a0e22ad77..ee43e0a9cb 100644
--- a/packages/type-jsonrpc/src/index.spec.js
+++ b/packages/type-jsonrpc/src/index.spec.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import interfaces from '.';
+import interfaces from './';
 
 describe('jsonrpc', () => {
   it('exports the available interfaces', () => {
diff --git a/packages/type-storage/src/fromMetadata/fromMetadata.spec.ts b/packages/type-storage/src/fromMetadata/fromMetadata.spec.ts
index 06bd3b7994..97e34a4cf1 100644
--- a/packages/type-storage/src/fromMetadata/fromMetadata.spec.ts
+++ b/packages/type-storage/src/fromMetadata/fromMetadata.spec.ts
@@ -7,7 +7,7 @@ import { Metadata } from '@polkadot/types';
 import json from '@polkadot/types/Metadata/v4/static';
 import { u8aToHex } from '@polkadot/util';
 
-import fromMetadata from '.';
+import fromMetadata from './';
 
 const keyring = testingPairs({ type: 'ed25519' });
 // Use the pre-generated metadata
diff --git a/packages/types/src/index.spec.ts b/packages/types/src/index.spec.ts
index 221a90dfa1..fa5bf2034e 100644
--- a/packages/types/src/index.spec.ts
+++ b/packages/types/src/index.spec.ts
@@ -2,10 +2,9 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { Constructor } from './types';
-
 import extrinsics from '@polkadot/extrinsics/static';
 
+import { Constructor } from './types';
 import * as Classes from './index.types';
 
 const Types = Classes as { [index: string]: Constructor };