4 files changed, 66 insertions, 0 deletions
diff --git a/js/src/tests/test262/annexB/language/statements/class/subclass/browser.js b/js/src/tests/test262/annexB/language/statements/class/subclass/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/annexB/language/statements/class/subclass/browser.js
diff --git a/js/src/tests/test262/annexB/language/statements/class/subclass/shell.js b/js/src/tests/test262/annexB/language/statements/class/subclass/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/annexB/language/statements/class/subclass/shell.js
diff --git a/js/src/tests/test262/annexB/language/statements/class/subclass/superclass-emulates-undefined.js b/js/src/tests/test262/annexB/language/statements/class/subclass/superclass-emulates-undefined.js
new file mode 100644
index 0000000000..245e7d402b
--- /dev/null
+++ b/js/src/tests/test262/annexB/language/statements/class/subclass/superclass-emulates-undefined.js
@@ -0,0 +1,35 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-runtime-semantics-classdefinitionevaluation
+description: >
+  [[IsHTMLDDA]] object as superclass: `null` check uses strict equality.
+  IsConstructor check is performed before "prototype" lookup.
+info: |
+  ClassDefinitionEvaluation
+
+  [...]
+  5. Else,
+    [...]
+    d. Let superclass be ? GetValue(superclassRef).
+    e. If superclass is null, then
+      [...]
+    f. Else if IsConstructor(superclass) is false, throw a TypeError exception.
+features: [class, IsHTMLDDA]
+---*/
+
+var superclass = $262.IsHTMLDDA;
+var prototypeGets = 0;
+Object.defineProperty(superclass, "prototype", {
+  get: function() {
+    prototypeGets += 1;
+  },
+});
+
+assert.throws(TypeError, function() {
+  class C extends superclass {}
+});
+
+assert.sameValue(prototypeGets, 0);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/annexB/language/statements/class/subclass/superclass-prototype-emulates-undefined.js b/js/src/tests/test262/annexB/language/statements/class/subclass/superclass-prototype-emulates-undefined.js
new file mode 100644
index 0000000000..542dbb0756
--- /dev/null
+++ b/js/src/tests/test262/annexB/language/statements/class/subclass/superclass-prototype-emulates-undefined.js
@@ -0,0 +1,31 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-runtime-semantics-classdefinitionevaluation
+description: >
+  [[IsHTMLDDA]] object as "prototype" of superclass: `null` check uses strict equality.
+info: |
+  ClassDefinitionEvaluation
+
+  [...]
+  5. Else,
+    [...]
+    g. Else,
+      i. Let protoParent be ? Get(superclass, "prototype").
+      ii. If Type(protoParent) is neither Object nor Null, throw a TypeError exception.
+      iii. Let constructorParent be superclass.
+  6. Let proto be OrdinaryObjectCreate(protoParent).
+  [...]
+features: [class, IsHTMLDDA]
+---*/
+
+function Superclass() {}
+Superclass.prototype = $262.IsHTMLDDA;
+
+class C extends Superclass {}
+var c = new C();
+
+assert(c instanceof C);
+assert(c instanceof Superclass);
+
+reportCompare(0, 0);