Fix tracking a page view with a custom title sets the title for future page views as well (close #1332)

PR #1334

Author: matus-tomlein

common/changes/@snowplow/browser-tracker-core/issue-1332-page_title_fix_2024-07-19-13-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@snowplow/browser-tracker-core",
+      "comment": "Fix tracking a page view with a custom title sets the title for future page views as well (#1332)",
+      "type": "none"
+    }
+  ],
+  "packageName": "@snowplow/browser-tracker-core"
+}

libraries/browser-tracker-core/src/tracker/index.ts

@@ -210,6 +210,10 @@ export function Tracker(
       lastDocumentTitle = document.title,
       // Custom title
       lastConfigTitle: string | null | undefined,
+      // Indicates that the lastConfigTitle was set from a trackPageView call
+      // Custom title configured this way has a shorter lifespan than when set using setDocumentTitle.
+      // It only lasts until the next trackPageView call.
+      lastConfigTitleFromTrackPageView: boolean = false,
       // Controls whether activity tracking page ping event timers are reset on page view events
       resetActivityTrackingOnPageView = trackerConfiguration.resetActivityTrackingOnPageView ?? true,
       // Disallow hash tags in URL. TODO: Should this be set to true by default?
@@ -987,7 +991,12 @@ export function Tracker(
 
       // So we know what document.title was at the time of trackPageView
       lastDocumentTitle = document.title;
-      lastConfigTitle = title ?? lastConfigTitle;
+      if (title) {
+        lastConfigTitle = title;
+        lastConfigTitleFromTrackPageView = true;
+      } else if (lastConfigTitleFromTrackPageView) {
+        lastConfigTitle = null;
+      }
 
       // Fixup page title
       const pageTitle = fixupTitle(lastConfigTitle || lastDocumentTitle);
@@ -1227,6 +1236,7 @@ export function Tracker(
         // So we know what document.title was at the time of trackPageView
         lastDocumentTitle = document.title;
         lastConfigTitle = title;
+        lastConfigTitleFromTrackPageView = false;
       },
 
       discardHashTag: function (enableFilter: boolean) {

libraries/browser-tracker-core/test/tracker/page_view.test.ts

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2022 Snowplow Analytics Ltd, 2010 Anthon Pang
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import { createTracker } from '../helpers';
+
+describe('Tracker API: page views', () => {
+  beforeEach(() => {
+    jest.spyOn(document, 'title', 'get').mockReturnValue('Page title 1');
+  });
+
+  it('Uses custom page title for only a single page view', () => {
+    let titles: string[] = [];
+    const tracker = createTracker({
+      plugins: [
+        {
+          afterTrack: (payload) => {
+            titles.push(payload.page as string);
+          },
+        },
+      ],
+    });
+
+    tracker?.trackPageView({
+      title: 'Title override',
+    });
+    tracker?.trackPageView();
+
+    expect(titles).toEqual(['Title override', 'Page title 1']);
+  });
+
+  it('Uses custom page title set using setDocumentTitle until overriden again', () => {
+    let titles: string[] = [];
+    const tracker = createTracker({
+      plugins: [
+        {
+          afterTrack: (payload) => {
+            titles.push(payload.page as string);
+          },
+        },
+      ],
+    });
+
+    tracker?.setDocumentTitle('Title override');
+    tracker?.trackPageView();
+    tracker?.trackPageView();
+
+    jest.spyOn(document, 'title', 'get').mockReturnValue('Page title 2');
+    tracker?.trackPageView();
+
+    tracker?.setDocumentTitle('Title override 2');
+    tracker?.trackPageView();
+
+    expect(titles).toEqual(['Title override', 'Title override', 'Title override', 'Title override 2']);
+  });
+
+  it('Explicit title in trackPageView overrides setDocumentTitle', () => {
+    let titles: string[] = [];
+    const tracker = createTracker({
+      plugins: [
+        {
+          afterTrack: (payload) => {
+            titles.push(payload.page as string);
+          },
+        },
+      ],
+    });
+
+    tracker?.setDocumentTitle('Title override');
+    tracker?.trackPageView({
+      title: 'Explicit title',
+    });
+    tracker?.trackPageView();
+
+    expect(titles).toEqual(['Explicit title', 'Page title 1']);
+  });
+});

trackers/javascript-tracker/test/integration/integration.test.ts

@@ -89,8 +89,7 @@ describe('Snowplow Micro integration', () => {
             platform: 'mob',
             app_id: `sp-${method}-${testIdentifier}`,
             user_id: 'Malcolm',
-            // The title is not correctly set due to #1332
-            // page_title: 'Integration test page',
+            page_title: 'Integration test page',
           },
         })
       ).toBe(true);