1 files changed, 240 insertions, 0 deletions
diff --git a/browser/components/translations/tests/browser/browser_translations_full_page_panel_fuzzing.js b/browser/components/translations/tests/browser/browser_translations_full_page_panel_fuzzing.js
new file mode 100644
index 0000000000..0accc3db60
--- /dev/null
+++ b/browser/components/translations/tests/browser/browser_translations_full_page_panel_fuzzing.js
@@ -0,0 +1,240 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Manually destroy the engine while a page is in the background, and test that the page
+ * is still translated after switching back to it.
+ */
+add_task(async function test_translations_panel_fuzzing() {
+  const {
+    cleanup,
+    runInPage: runInSpanishPage,
+    tab: spanishTab,
+  } = await loadTestPage({
+    page: SPANISH_PAGE_URL,
+    languagePairs: LANGUAGE_PAIRS,
+    autoDownloadFromRemoteSettings: true,
+  });
+
+  /**
+   * @typedef {object} Tab
+   */
+
+  /** @type {Tab?} */
+  let englishTab;
+  /** @type {Function?} */
+  let removeEnglishTab;
+  /** @type {boolean} */
+  let isSpanishPageTranslated = false;
+  /** @type {"spanish" | "english"} */
+  let activeTab = "spanish";
+  /** @type {boolean} */
+  let isEngineMaybeDestroyed = true;
+  /** @type {boolean} */
+  let isTitleMutated = false;
+  /** @type {boolean} */
+  let hasVerifiedMutation = true;
+
+  function reportOperation(name) {
+    info(
+      `\n\nOperation: ${name} ` +
+        JSON.stringify({
+          activeTab,
+          englishTab: !!englishTab,
+          isSpanishPageTranslated,
+          isEngineMaybeDestroyed,
+          isTitleMutated,
+        })
+    );
+  }
+
+  /**
+   * A list of fuzzing operations. They return false when they are a noop given the
+   * conditions.
+   *
+   * @type {object} - Record<string, () => Promise<boolean>>
+   */
+  const operations = {
+    async addEnglishTab() {
+      if (!englishTab) {
+        reportOperation("addEnglishTab");
+        const { removeTab, tab } = await addTab(
+          ENGLISH_PAGE_URL,
+          "Creating a new tab for a page in English."
+        );
+
+        englishTab = tab;
+        removeEnglishTab = removeTab;
+        activeTab = "english";
+        return true;
+      }
+      return false;
+    },
+
+    async removeEnglishTab() {
+      if (removeEnglishTab) {
+        reportOperation("removeEnglishTab");
+        await removeEnglishTab();
+
+        englishTab = null;
+        removeEnglishTab = null;
+        activeTab = "spanish";
+        return true;
+      }
+      return false;
+    },
+
+    async translateSpanishPage() {
+      if (!isSpanishPageTranslated) {
+        reportOperation("translateSpanishPage");
+        if (activeTab === "english") {
+          await switchTab(spanishTab, "spanish tab");
+        }
+        await FullPageTranslationsTestUtils.assertTranslationsButton(
+          { button: true },
+          "The button is available."
+        );
+        await FullPageTranslationsTestUtils.openPanel({
+          onOpenPanel: FullPageTranslationsTestUtils.assertPanelViewDefault,
+        });
+
+        await FullPageTranslationsTestUtils.clickTranslateButton();
+
+        await FullPageTranslationsTestUtils.assertTranslationsButton(
+          { button: true, circleArrows: false, locale: true, icon: true },
+          "Translations button is fully loaded."
+        );
+
+        await FullPageTranslationsTestUtils.assertPageIsTranslated(
+          "es",
+          "en",
+          runInSpanishPage
+        );
+
+        isSpanishPageTranslated = true;
+        isEngineMaybeDestroyed = false;
+        activeTab = "spanish";
+        return true;
+      }
+      return false;
+    },
+
+    async destroyEngineProcess() {
+      if (
+        !isEngineMaybeDestroyed &&
+        // Don't destroy the engine process until the mutation has been verified.
+        // There is an artifical race (e.g. only in tests) that happens from a new
+        // engine being requested, and forcefully destroyed before the it can be
+        // initialized.
+        hasVerifiedMutation
+      ) {
+        reportOperation("destroyEngineProcess");
+        await EngineProcess.destroyTranslationsEngine();
+        isEngineMaybeDestroyed = true;
+      }
+      return true;
+    },
+
+    async mutateSpanishPage() {
+      if (isSpanishPageTranslated && !isTitleMutated) {
+        reportOperation("mutateSpanishPage");
+
+        info("Mutate the page's content to re-trigger a translation.");
+        await runInSpanishPage(async TranslationsTest => {
+          const { getH1 } = TranslationsTest.getSelectors();
+          getH1().innerText = "New text for the H1";
+        });
+
+        if (isEngineMaybeDestroyed) {
+          info("The engine may be recreated now.");
+        }
+
+        isEngineMaybeDestroyed = false;
+        isTitleMutated = true;
+        hasVerifiedMutation = false;
+        return true;
+      }
+      return false;
+    },
+
+    async switchToSpanishTab() {
+      if (activeTab !== "spanish") {
+        reportOperation("switchToSpanishTab");
+        await switchTab(spanishTab, "spanish tab");
+        activeTab = "spanish";
+
+        if (isTitleMutated) {
+          await runInSpanishPage(async TranslationsTest => {
+            const { getH1 } = TranslationsTest.getSelectors();
+            await TranslationsTest.assertTranslationResult(
+              "The mutated content should be translated.",
+              getH1,
+              "NEW TEXT FOR THE H1 [es to en]"
+            );
+          });
+          hasVerifiedMutation = true;
+        }
+
+        return true;
+      }
+      return false;
+    },
+
+    async switchToEnglishTab() {
+      if (activeTab !== "english" && englishTab) {
+        reportOperation("switchToEnglishTab");
+        await switchTab(englishTab, "english tab");
+        activeTab = "english";
+        return true;
+      }
+      return false;
+    },
+
+    async restoreSpanishPage() {
+      if (activeTab === "spanish" && isSpanishPageTranslated) {
+        reportOperation("restoreSpanishPage");
+        await FullPageTranslationsTestUtils.openPanel({
+          onOpenPanel: FullPageTranslationsTestUtils.assertPanelViewRevisit,
+        });
+
+        await FullPageTranslationsTestUtils.clickRestoreButton();
+
+        await FullPageTranslationsTestUtils.assertPageIsUntranslated(
+          runInSpanishPage
+        );
+
+        await FullPageTranslationsTestUtils.assertTranslationsButton(
+          { button: true, circleArrows: false, locale: false, icon: true },
+          "The button is reverted to have an icon."
+        );
+
+        isSpanishPageTranslated = false;
+        isTitleMutated = false;
+        return true;
+      }
+      return false;
+    },
+  };
+
+  const fuzzSteps = 100;
+  info(`Starting the fuzzing with ${fuzzSteps} operations.`);
+  const opsArray = Object.values(operations);
+
+  for (let i = 0; i < fuzzSteps; i++) {
+    // Pick a random operation and check if that it was not a noop, otherwise continue
+    // trying to find a valid operation.
+    while (true) {
+      const operation = opsArray[Math.floor(Math.random() * opsArray.length)];
+      if (await operation()) {
+        break;
+      }
+    }
+  }
+
+  if (removeEnglishTab) {
+    await removeEnglishTab();
+  }
+  await cleanup();
+});