Fix unsubscribe and add a test (#4058)

CHANGELOG.md

@@ -441,3 +441,4 @@ Released with 1.0.0-beta.37 code base.
 - lerna from 3.22.1 to 4.0.0 (#4231)
 - Dropped build tests in CI for Node v8 and v10, and added support for Node v14
 - Change default value for `maxPriorityFeePerGas` from `1 Gwei` to `2.5 Gwei` (#4284)
+- Emit subscription id with connect event when creating a subscription (#4300)

packages/web3-core-subscriptions/src/subscription.js

@@ -281,7 +281,6 @@ Subscription.prototype.subscribe = function() {
         if(!err && result) {
             _this.id = result;
             _this.method = payload.params[0];
-            _this.emit('connected', result);
 
             // call callback on notifications
             _this.options.requestManager.addSubscription(_this, function(error, result) {
@@ -310,6 +309,7 @@ Subscription.prototype.subscribe = function() {
                     _this.emit('error', error);
                 }
             });
+            _this.emit('connected', result);
         } else {
             setTimeout(function(){
                 _this.callback(err, false, _this);

test/eth.subscribe.ganache.js

@@ -54,6 +54,18 @@ describe('subscription connect/reconnect', function () {
             });
     });
 
+    it('unsubscribe should remove the subscription object from the subscriptions and send eth_unsubscribe to the node', function (done) {
+        subscription = web3.eth
+            .subscribe('newBlockHeaders')
+            .on('connected', function () {
+                const id = subscription.id;
+                assert(subscription.options.requestManager.subscriptions.has(id));
+                subscription.unsubscribe(); // Send eth_unsubscribe to the node
+                assert(!subscription.options.requestManager.subscriptions.has(id));
+                done();
+            });
+    });
+
     it('clearSubscriptions', async function() {
         web3.eth.subscribe('newBlockHeaders');
         await waitSeconds(1); // Sub need a little time to set up