1 files changed, 70 insertions, 0 deletions
diff --git a/devtools/server/actors/webconsole/message-manager-mock.js b/devtools/server/actors/webconsole/message-manager-mock.js
new file mode 100644
index 0000000000..900dfcb3d5
--- /dev/null
+++ b/devtools/server/actors/webconsole/message-manager-mock.js
@@ -0,0 +1,70 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/**
+ * Implements a fake MessageManager class that allows to use the message
+ * manager API within the same process. This implementation will forward
+ * messages within the same process.
+ *
+ * It helps having the same codepath for actors being evaluated in the same
+ * process *and* in a remote one.
+ */
+function MessageManagerMock() {
+  this._listeners = new Map();
+}
+MessageManagerMock.prototype = {
+  addMessageListener(name, listener) {
+    let listeners = this._listeners.get(name);
+    if (!listeners) {
+      listeners = [];
+      this._listeners.set(name, listeners);
+    }
+    if (!listeners.includes(listener)) {
+      listeners.push(listener);
+    }
+  },
+  removeMessageListener(name, listener) {
+    const listeners = this._listeners.get(name);
+    const idx = listeners.indexOf(listener);
+    listeners.splice(idx, 1);
+  },
+  sendAsyncMessage(name, data) {
+    this.other.internalSendAsyncMessage(name, data);
+  },
+  internalSendAsyncMessage(name, data) {
+    const listeners = this._listeners.get(name);
+    if (!listeners) {
+      return;
+    }
+    const message = {
+      target: this,
+      data,
+    };
+    for (const listener of listeners) {
+      if (
+        typeof listener === "object" &&
+        typeof listener.receiveMessage === "function"
+      ) {
+        listener.receiveMessage(message);
+      } else if (typeof listener === "function") {
+        listener(message);
+      }
+    }
+  },
+};
+
+/**
+ * Create two MessageManager mocks, connected to each others.
+ * Calling sendAsyncMessage on the first will dispatch messages on the second one,
+ * and the other way around
+ */
+exports.createMessageManagerMocks = function() {
+  const a = new MessageManagerMock();
+  const b = new MessageManagerMock();
+  a.other = b;
+  b.other = a;
+  return [a, b];
+};