http2: invoke connect callback immediately if session was connected

doc/api/http2.md

@@ -320,6 +320,17 @@ added: v9.4.0
 Will be `true` if this `Http2Session` instance has been closed, otherwise
 `false`.
 
+#### http2session.connecting
+<!-- YAML
+added: REPLACEME
+-->
+
+* {boolean}
+
+Will be `true` if this `Http2Session` instance is still connecting, will be set
+to `false` before emitting `connect` event and/or calling the `http2.connect`
+callback.
+
 #### http2session.destroy([error,][code])
 <!-- YAML
 added: v8.4.0

lib/internal/http2/core.js

@@ -774,7 +774,7 @@ function setupHandle(socket, type, options) {
   // core will check for session.destroyed before progressing, this
   // ensures that those at l`east get cleared out.
   if (this.destroyed) {
-    this.emit('connect', this, socket);
+    process.nextTick(emit, this, 'connect', this, socket);
     return;
   }
   debug(`Http2Session ${sessionName(type)}: setting up session handle`);
@@ -816,7 +816,7 @@ function setupHandle(socket, type, options) {
     options.settings : {};
 
   this.settings(settings);
-  this.emit('connect', this, socket);
+  process.nextTick(emit, this, 'connect', this, socket);
 }
 
 // Emits a close event followed by an error event if err is truthy. Used

test/parallel/test-http2-connect.js

@@ -4,6 +4,9 @@ const { mustCall, hasCrypto, skip, expectsError } = require('../common');
 if (!hasCrypto)
   skip('missing crypto');
 const { createServer, connect } = require('http2');
+const { connect: netConnect } = require('net');
+
+// check for session connect callback and event
 {
   const server = createServer();
   server.listen(0, mustCall(() => {
@@ -30,6 +33,28 @@ const { createServer, connect } = require('http2');
   }));
 }
 
+// check for session connect callback on already connected socket
+{
+  const server = createServer();
+  server.listen(0, mustCall(() => {
+    const { port } = server.address();
+
+    const onSocketConnect = () => {
+      const authority = `http://localhost:${port}`;
+      const createConnection = mustCall(() => socket);
+      const options = { createConnection };
+      connect(authority, options, mustCall(onSessionConnect));
+    };
+
+    const onSessionConnect = (session) => {
+      session.close();
+      server.close();
+    };
+
+    const socket = netConnect(port, mustCall(onSocketConnect));
+  }));
+}
+
 // check for https as protocol
 {
   const authority = 'https://localhost';