From 09427933ac4883cb6cbe756eaa9c980eb8b76b1d Mon Sep 17 00:00:00 2001
From: Domenic Denicola <d@domenic.me>
Date: Wed, 12 Oct 2022 20:11:46 +0900
Subject: [PATCH] Test that History is associated with Document, not Window

This is done by expanding the object-association.js helper and using it.

We can also remove an outdated workaround in that file for extra load events, since no modern browsers suffer from that.

See https://github.com/whatwg/html/issues/2566.
---
 common/object-association.js                  | 68 ++++++++++---------
 ...history-associated-with-document.window.js |  6 ++
 2 files changed, 43 insertions(+), 31 deletions(-)
 create mode 100644 html/browsers/history/the-history-interface/history-associated-with-document.window.js

diff --git a/common/object-association.js b/common/object-association.js
index 458aae67db0cef..669c17c07b1ae5 100644
--- a/common/object-association.js
+++ b/common/object-association.js
@@ -1,58 +1,64 @@
 "use strict";
 
-// For now this only has per-Window tests, but we could expand it to also test per-Document
+// This is for testing whether an object (e.g., a global property) is associated with Window, or
+// with Document. Recall that Window and Document are 1:1 except when doing a same-origin navigation
+// away from the initial about:blank. In that case the Window object gets reused for the new
+// Document.
+//
+// So:
+// - If something is per-Window, then it should maintain its identity across an about:blank
+//   navigation.
+// - If something is per-Document, then it should be recreated across an about:blank navigation.
 
-/**
- * Run tests for window[propertyName] after discarding the browsing context, navigating, etc.
- * @param {string} propertyName
- */
 window.testIsPerWindow = propertyName => {
-  test(t => {
+  runTests(propertyName, assert_equals, "must not");
+};
+
+window.testIsPerDocument = propertyName => {
+  runTests(propertyName, assert_not_equals, "must");
+};
+
+function runTests(propertyName, equalityOrInequalityAsserter, mustOrMustNotReplace) {
+  async_test(t => {
     const iframe = document.createElement("iframe");
     document.body.appendChild(iframe);
     const frame = iframe.contentWindow;
 
     const before = frame[propertyName];
-    assert_true(before !== undefined && before !== null, `window.${propertyName} must be implemented`);
+    assert_implements(before, `window.${propertyName} must be implemented`);
 
-    iframe.remove();
+    iframe.onload = t.step_func_done(() => {
+      const after = frame[propertyName];
+      equalityOrInequalityAsserter(after, before);
+    });
 
-    const after = frame[propertyName];
-    assert_equals(after, before, `window.${propertyName} should not change after iframe.remove()`);
-  }, `Discarding the browsing context must not change window.${propertyName}`);
+    iframe.src = "/common/blank.html";
+  }, `Navigating from the initial about:blank ${mustOrMustNotReplace} replace window.${propertyName}`);
 
-  async_test(t => {
+  // Per spec, discarding a browsing context should not change any of the global objects.
+  test(() => {
     const iframe = document.createElement("iframe");
     document.body.appendChild(iframe);
     const frame = iframe.contentWindow;
 
     const before = frame[propertyName];
-    assert_true(before !== undefined && before !== null, `window.${propertyName} must be implemented`);
-
-    // Note: cannot use step_func_done for this because it might be called twice, per the below comment.
-    iframe.onload = t.step_func(() => {
-      if (frame.location.href === "about:blank") {
-        // Browsers are not reliable on whether about:blank fires the load event; see
-        // https://github.com/whatwg/html/issues/490
-        return;
-      }
+    assert_implements(before, `window.${propertyName} must be implemented`);
 
-      const after = frame[propertyName];
-      assert_equals(after, before);
-      t.done();
-    });
+    iframe.remove();
 
-    iframe.src = "/common/blank.html";
-  }, `Navigating from the initial about:blank must not replace window.${propertyName}`);
+    const after = frame[propertyName];
+    assert_equals(after, before, `window.${propertyName} should not change after iframe.remove()`);
+  }, `Discarding the browsing context must not change window.${propertyName}`);
 
-  // Per spec, document.open() should not change any of the Window state.
+  // Per spec, document.open() should not change any of the global objects. In historical versions
+  // of the spec, it did, so we test here.
   async_test(t => {
     const iframe = document.createElement("iframe");
 
     iframe.onload = t.step_func_done(() => {
       const frame = iframe.contentWindow;
       const before = frame[propertyName];
-      assert_true(before !== undefined && before !== null, `window.${propertyName} must be implemented`);
+      assert_implements(before, `window.${propertyName} must be implemented`);
 
       frame.document.open();
 
@@ -64,5 +70,5 @@ window.testIsPerWindow = propertyName => {
 
     iframe.src = "/common/blank.html";
     document.body.appendChild(iframe);
-  }, `document.open() must replace window.${propertyName}`);
-};
+  }, `document.open() must not replace window.${propertyName}`);
+}
diff --git a/html/browsers/history/the-history-interface/history-associated-with-document.window.js b/html/browsers/history/the-history-interface/history-associated-with-document.window.js
new file mode 100644
index 00000000000000..94c1b2cf6b0a4b
--- /dev/null
+++ b/html/browsers/history/the-history-interface/history-associated-with-document.window.js
@@ -0,0 +1,6 @@
+// META: title=the History object must be associated with the Document object, not the Window object
+// META: script=/common/object-association.js
+
+// See https://github.com/whatwg/html/issues/2566.
+
+testIsPerDocument("history");