Encode mock responses as JSON (#66)

* Encode mock responses as JSON

* Update primitives

packages/api-format/src/output.js

@@ -8,6 +8,7 @@ import type { InterfaceOutputType } from '@polkadot/api-jsonrpc/types';
 const bnDecode = require('@polkadot/primitives-json/bn/decode');
 const bytesDecode = require('@polkadot/primitives-json/bytes/decode');
 const headerDecode = require('@polkadot/primitives-json/header/decode');
+const isNull = require('@polkadot/util/is/null');
 const isUndefined = require('@polkadot/util/is/undefined');
 
 const util = require('./util');
@@ -20,8 +21,8 @@ const formatters = {
 };
 
 module.exports = function formatOutput (output: InterfaceOutputType, value?: mixed): ?mixed {
-  if (isUndefined(value)) {
-    return void 0;
+  if (isUndefined(value) || isNull(value)) {
+    return value;
   }
 
   return util.format(formatters, output.type, value);

packages/api-format/src/output.spec.js

@@ -11,13 +11,13 @@ describe('formatOutput', () => {
     expect(
       JSON.stringify(
         formatOutput({ type: 'Header' }, {
-          parentHash: '0x1234',
-          number: '0x1234',
-          stateRoot: '0x5678',
-          transactionRoot: '0xabcd',
           digest: {
             logs: ['0x5678', '0x789a']
-          }
+          },
+          extrinsicsRoot: '0xabcd',
+          number: '0x1234',
+          parentHash: '0x1234',
+          stateRoot: '0x5678'
         })
       )
     ).toEqual(
@@ -28,10 +28,10 @@ describe('formatOutput', () => {
             new Uint8Array([0x78, 0x9a])
           ]
         },
+        extrinsicsRoot: new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xab, 0xcd]),
         number: new BN(0x1234),
         parentHash: new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x12, 0x34]),
-        stateRoot: new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x56, 0x78]),
-        transactionRoot: new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xab, 0xcd])
+        stateRoot: new Uint8Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x56, 0x78])
       })
     );
   });