1 files changed, 48 insertions, 0 deletions
diff --git a/testing/web-platform/tests/dom/nodes/insertion-removing-steps/insertion-removing-steps-script.window.js b/testing/web-platform/tests/dom/nodes/insertion-removing-steps/insertion-removing-steps-script.window.js
new file mode 100644
index 0000000000..a1be3e1dd3
--- /dev/null
+++ b/testing/web-platform/tests/dom/nodes/insertion-removing-steps/insertion-removing-steps-script.window.js
@@ -0,0 +1,48 @@
+promise_test(async t => {
+  const fragmentWithTwoScripts = new DocumentFragment();
+  const script0 = document.createElement('script');
+  const script1 = fragmentWithTwoScripts.appendChild(document.createElement('script'));
+  const script2 = fragmentWithTwoScripts.appendChild(document.createElement('script'));
+
+  window.kBaselineNumberOfScripts = document.scripts.length;
+  assert_equals(document.scripts.length, kBaselineNumberOfScripts,
+      "The WPT infra starts out with exactly 3 scripts");
+
+  window.script0Executed = false;
+  script0.innerText = `
+    script0Executed = true;
+    assert_equals(document.scripts.length, kBaselineNumberOfScripts + 1,
+        'script0 can observe itself and no other scripts');
+  `;
+
+  window.script1Executed = false;
+  script1.innerText = `
+    script1Executed = true;
+    assert_equals(document.scripts.length, kBaselineNumberOfScripts + 2,
+        "script1 executes synchronously, and thus observes only itself and " +
+        "previous scripts");
+  `;
+
+  window.script2Executed = false;
+  script2.innerText = `
+    script2Executed = true;
+    assert_equals(document.scripts.length, kBaselineNumberOfScripts + 3,
+        "script2 executes synchronously, and thus observes itself and all " +
+        "previous scripts");
+  `;
+
+  assert_false(script0Executed, "Script0 does not execute before append()");
+  document.body.append(script0);
+  assert_true(script0Executed,
+      "Script0 executes synchronously during append()");
+
+  assert_false(script1Executed, "Script1 does not execute before append()");
+  assert_false(script2Executed, "Script2 does not execute before append()");
+  document.body.append(fragmentWithTwoScripts);
+  assert_true(script1Executed,
+      "Script1 executes synchronously during fragment append()");
+  assert_true(script2Executed,
+      "Script2 executes synchronously during fragment append()");
+}, "Script node insertion is not atomic with regard to execution. Each " +
+   "script is synchronously executed during the HTML element insertion " +
+   "steps hook");