From 59e069f0915a8d647db9b0d32c6686ebb87e044d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20P=C3=A1nik?= <jakub.panik@gmail.com>
Date: Thu, 30 Jan 2020 16:48:11 +0100
Subject: [PATCH] Added unsubscribe return function to wsProvider.on() (#1780)

* Added unsubscribe return function to wsProvider.on()

* Updated mocks, added noop to http provider
---
 packages/rpc-provider/src/http/index.ts  | 5 ++++-
 packages/rpc-provider/src/mock/index.ts  | 5 ++++-
 packages/rpc-provider/src/types.ts       | 2 +-
 packages/rpc-provider/src/ws/Provider.ts | 6 +++++-
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/packages/rpc-provider/src/http/index.ts b/packages/rpc-provider/src/http/index.ts
index 10d54ccfde..02a603c1e5 100644
--- a/packages/rpc-provider/src/http/index.ts
+++ b/packages/rpc-provider/src/http/index.ts
@@ -84,8 +84,11 @@ export default class HttpProvider implements ProviderInterface {
    * @description HTTP Provider does not have 'on' emitters. WebSockets should be used instead.
    */
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  public on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): void {
+  public on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): () => void {
     l.error('HTTP Provider does not have \'on\' emitters, use WebSockets instead');
+    return (): void => {
+      // noop
+    };
   }
 
   /**
diff --git a/packages/rpc-provider/src/mock/index.ts b/packages/rpc-provider/src/mock/index.ts
index 080c6749f4..d80f65d8f3 100644
--- a/packages/rpc-provider/src/mock/index.ts
+++ b/packages/rpc-provider/src/mock/index.ts
@@ -104,8 +104,11 @@ export default class Mock implements ProviderInterface {
     return true;
   }
 
-  public on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): void {
+  public on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): () => void {
     this.emitter.on(type, sub);
+    return (): void => {
+      this.emitter.removeListener(type, sub);
+    };
   }
 
   // eslint-disable-next-line @typescript-eslint/require-await
diff --git a/packages/rpc-provider/src/types.ts b/packages/rpc-provider/src/types.ts
index 96559ce626..aa9dcb499e 100644
--- a/packages/rpc-provider/src/types.ts
+++ b/packages/rpc-provider/src/types.ts
@@ -47,7 +47,7 @@ export interface ProviderInterface {
   clone (): ProviderInterface;
   disconnect (): void;
   isConnected (): boolean;
-  on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): void;
+  on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): () => void;
   send (method: string, params: any[]): Promise<any>;
   subscribe (type: string, method: string, params: any[], cb: ProviderInterfaceCallback): Promise<number>;
   unsubscribe (type: string, method: string, id: number): Promise<boolean>;
diff --git a/packages/rpc-provider/src/ws/Provider.ts b/packages/rpc-provider/src/ws/Provider.ts
index 2f5a24312c..1352e941c5 100644
--- a/packages/rpc-provider/src/ws/Provider.ts
+++ b/packages/rpc-provider/src/ws/Provider.ts
@@ -167,9 +167,13 @@ export default class WsProvider implements WSProviderInterface {
    * @summary Listens on events after having subscribed using the [[subscribe]] function.
    * @param  {ProviderInterfaceEmitted} type Event
    * @param  {ProviderInterfaceEmitCb}  sub  Callback
+   * @return unsubscribe function
    */
-  public on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): void {
+  public on (type: ProviderInterfaceEmitted, sub: ProviderInterfaceEmitCb): () => void {
     this._eventemitter.on(type, sub);
+    return (): void => {
+      this._eventemitter.removeListener(type, sub);
+    };
   }
 
   /**