1 files changed, 74 insertions, 0 deletions
diff --git a/testing/web-platform/tests/common/object-association.js b/testing/web-platform/tests/common/object-association.js
new file mode 100644
index 0000000000..669c17c07b
--- /dev/null
+++ b/testing/web-platform/tests/common/object-association.js
@@ -0,0 +1,74 @@
+"use strict";
+
+// 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.
+
+window.testIsPerWindow = propertyName => {
+  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_implements(before, `window.${propertyName} must be implemented`);
+
+    iframe.onload = t.step_func_done(() => {
+      const after = frame[propertyName];
+      equalityOrInequalityAsserter(after, before);
+    });
+
+    iframe.src = "/common/blank.html";
+  }, `Navigating from the initial about:blank ${mustOrMustNotReplace} replace window.${propertyName}`);
+
+  // 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_implements(before, `window.${propertyName} must be implemented`);
+
+    iframe.remove();
+
+    const after = frame[propertyName];
+    assert_equals(after, before, `window.${propertyName} should not change after iframe.remove()`);
+  }, `Discarding the browsing context must not change window.${propertyName}`);
+
+  // Per spec, document.open() should not change any of the global objects. In historical versions
+  // of the spec, it did, so we test here.
+  async_test(t => {
+    const iframe = document.createElement("iframe");
+
+    iframe.onload = t.step_func_done(() => {
+      const frame = iframe.contentWindow;
+      const before = frame[propertyName];
+      assert_implements(before, `window.${propertyName} must be implemented`);
+
+      frame.document.open();
+
+      const after = frame[propertyName];
+      assert_equals(after, before);
+
+      frame.document.close();
+    });
+
+    iframe.src = "/common/blank.html";
+    document.body.appendChild(iframe);
+  }, `document.open() must not replace window.${propertyName}`);
+}