tests: Support injecting hook functions during pad load

CHANGELOG.md

@@ -47,6 +47,9 @@
     hook. Plugins should use this instead of the `clientVars` global variable.
   * New `userJoin` server-side hook.
   * The `userLeave` server-side hook has a new `socket` context property.
+  * The `helper.aNewPad()` function (accessible to client-side tests) now
+    accepts hook functions to inject when opening a pad. This can be used to
+    test any new client-side hooks your plugin provides.
 
 # 1.8.14
 

src/templates/pad.html

@@ -478,6 +478,10 @@
 
         plugins.baseURL = baseURL;
         plugins.update(function () {
+          // Mechanism for tests to register hook functions (install fake plugins).
+          window._postPluginUpdateForTestingDone = false;
+          if (window._postPluginUpdateForTesting != null) window._postPluginUpdateForTesting();
+          window._postPluginUpdateForTestingDone = true;
           // Call documentReady hook
           $(function() {
             hooks.aCallAll('documentReady');

src/tests/frontend/helper.js

@@ -96,6 +96,7 @@ const helper = {};
       _retry: 0,
       clearCookies: true,
       id: `FRONTEND_TEST_${helper.randomString(20)}`,
+      hookFns: {},
     }, opts);
 
     // if opts.params is set we manipulate the URL to include URL parameters IE ?foo=Bah.
@@ -122,7 +123,26 @@ const helper = {};
     $('#iframe-container iframe').remove();
     // set new iframe
     $('#iframe-container').append($iframe);
-    await new Promise((resolve) => $iframe.one('load', resolve));
+    await Promise.all([
+      new Promise((resolve) => $iframe.one('load', resolve)),
+      // Install the hook functions as early as possible because some of them fire right away.
+      new Promise((resolve, reject) => {
+        if ($iframe[0].contentWindow._postPluginUpdateForTestingDone) {
+          return reject(new Error(
+              'failed to set _postPluginUpdateForTesting before it would have been called'));
+        }
+        $iframe[0].contentWindow._postPluginUpdateForTesting = () => {
+          const {hooks} =
+                $iframe[0].contentWindow.require('ep_etherpad-lite/static/js/pluginfw/plugin_defs');
+          for (const [hookName, hookFns] of Object.entries(opts.hookFns)) {
+            if (hooks[hookName] == null) hooks[hookName] = [];
+            hooks[hookName].push(
+                ...hookFns.map((hookFn) => ({hook_name: hookName, hook_fn: hookFn})));
+          }
+          resolve();
+        };
+      }),
+    ]);
     helper.padChrome$ = await helper.getFrameJQuery($('#iframe-container iframe'), true);
     helper.padChrome$.padeditor =
         helper.padChrome$.window.require('ep_etherpad-lite/static/js/pad_editor').padeditor;