[FABN-1000] Use less strict "is promise" check

In complex Node.js applications, two or more promise implementations
may be available, providing different Promise classes. These different
Promise classes have the same standard interface, but you cannot rely
on instanceof to work as you would expect.

This has been seen as a problem in the ctor for AbstractEventStrategy
when running within VSCode, where an error is thrown because a promise
is not an instanceof Promise (even though it is a valid promise!).

Use the "is-promise" module instead which checks to see if the object
is "thenable" (has a .then()) method instead.

Change-Id: I6f47877b9be5815379163ffe5dc8d8cae1deba7b
Signed-off-by: Simon Stone <sstone1@uk.ibm.com>

fabric-network/lib/impl/event/abstracteventstrategy.js

@@ -6,6 +6,7 @@
 
 'use strict';
 
+const isPromise = require('is-promise');
 const logger = require('fabric-network/lib/logger').getLogger('AbstractStrategy');
 
 /**
@@ -24,7 +25,7 @@ class AbstractEventStrategy {
 	 * @param {Promise.ChannelEventHub[]} eventHubsPromise Promise to event hubs for which to process events.
 	 */
 	constructor(eventHubsPromise) {
-		if (!(eventHubsPromise instanceof Promise)) {
+		if (!isPromise(eventHubsPromise)) {
 			const message = 'Expected event hubs to be a Promise but was ' + typeof eventHubsPromise;
 			logger.error('constructor:', message);
 			throw new Error(message);

fabric-network/package.json

@@ -22,6 +22,7 @@
   },
   "types": "./types/index.d.ts",
   "dependencies": {
+    "is-promise": "^2.1.0",
     "nano": "^6.4.4",
     "rimraf": "^2.6.2",
     "uuid": "^3.2.1"