Issue #1899 - Make sure the test for it still works

Some hoops to make sure the test still works if the default value for the pref is false, requiring setting and resetting it and making sure the observers have time to react to these changes before testing.
1 month ago · 349d3d96a2
2 changed files with 45 additions and 2 deletions
--- a/devtools/client/inspector/rules/test/browser_rules_context-menu-show-mdn-docs-01.js
+++ b/devtools/client/inspector/rules/test/browser_rules_context-menu-show-mdn-docs-01.js
@ -20,6 +20,11 @@
 * code by having a tag called "padding" and a property
 * value called "margin".
 */
+
+const { PrefObserver } = require("devtools/client/shared/prefs");
+const PREF_ENABLE_MDN_DOCS_TOOLTIP =
+  "devtools.inspector.mdnDocsTooltip.enabled";
+
 const TEST_URI = `
  <html>
    <head>
@ -35,12 +40,50 @@ const TEST_URI = `
 `;

 add_task(function* () {
+  info("Ensure the pref is true to begin with");
+  let initial = Services.prefs.getBoolPref(PREF_ENABLE_MDN_DOCS_TOOLTIP);
+  if (initial != true) {
+    yield setBooleanPref(PREF_ENABLE_MDN_DOCS_TOOLTIP, true);
+  }
+
  yield addTab("data:text/html;charset=utf8," + encodeURIComponent(TEST_URI));
  let {inspector, view} = yield openRuleView();
  yield selectNode("padding", inspector);
  yield testMdnContextMenuItemVisibility(view);
+
+  info("Ensure the pref is reset to its initial value");
+  let eventual = Services.prefs.getBoolPref(PREF_ENABLE_MDN_DOCS_TOOLTIP);
+  if (eventual != initial) {
+    yield setBooleanPref(PREF_ENABLE_MDN_DOCS_TOOLTIP, initial);
+  }
 });

+/**
+ * Set a boolean pref, and wait for the pref observer to
+ * trigger, so that code listening for the pref change
+ * has had a chance to update itself.
+ *
+ * @param pref {string} Name of the pref to change
+ * @param state {boolean} Desired value of the pref.
+ *
+ * Note that if the pref already has the value in `state`,
+ * then the prefObserver will not trigger. So you should only
+ * call this function if you know the pref's current value is
+ * not `state`.
+ */
+function* setBooleanPref(pref, state) {
+  let oncePrefChanged = defer();
+  let prefObserver = new PrefObserver("devtools.");
+  prefObserver.on(pref, oncePrefChanged.resolve);
+
+  info("Set the pref " + pref + " to: " + state);
+  Services.prefs.setBoolPref(pref, state);
+
+  info("Wait for prefObserver to call back so the UI can update");
+  yield oncePrefChanged.promise;
+  prefObserver.off(pref, oncePrefChanged.resolve);
+}
+
 /**
 * Tests that the MDN context menu item is shown when it should be,
 * and hidden when it should be.
--- a/devtools/client/inspector/rules/test/browser_rules_context-menu-show-mdn-docs-03.js
+++ b/devtools/client/inspector/rules/test/browser_rules_context-menu-show-mdn-docs-03.js
@ -32,7 +32,7 @@ add_task(function* () {
  info("Ensure the pref is true to begin with");
  let initial = Services.prefs.getBoolPref(PREF_ENABLE_MDN_DOCS_TOOLTIP);
  if (initial != true) {
-    setBooleanPref(PREF_ENABLE_MDN_DOCS_TOOLTIP, true);
+    yield setBooleanPref(PREF_ENABLE_MDN_DOCS_TOOLTIP, true);
  }

  yield addTab("data:text/html;charset=utf8," + encodeURIComponent(TEST_DOC));
@ -58,7 +58,7 @@ add_task(function* () {
  info("Ensure the pref is reset to its initial value");
  let eventual = Services.prefs.getBoolPref(PREF_ENABLE_MDN_DOCS_TOOLTIP);
  if (eventual != initial) {
-    setBooleanPref(PREF_ENABLE_MDN_DOCS_TOOLTIP, initial);
+    yield setBooleanPref(PREF_ENABLE_MDN_DOCS_TOOLTIP, initial);
  }
 });