Add tests for `%WrapForValidIteratorPrototype%.return()` from Iterator Helpers Proposal (#4214)

* Add tests for `%WrapForValidIteratorPrototype%.return()`

* Address review

- Remove unused `flags
- Do not use `deepEqual.js`
- Assert `return` never got when `this` value is invalid
- Use `TemporalHelpers` to observer get / call

test/built-ins/Iterator/from/get-return-method-when-call-return.js

@@ -0,0 +1,35 @@
+// Copyright (C) 2024 Sosuke Suzuki. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-iterator.from
+description: >
+  Gets the base iterator return method when the wrapper return method is called.
+info: |
+  %WrapForValidIteratorPrototype%.return ( )
+    ...
+    5. Let returnMethod be ? GetMethod(iterator, "return").
+
+features: [iterator-helpers]
+includes: [temporalHelpers.js, compareArray.js]
+---*/
+
+const calls = [];
+
+const iter = TemporalHelpers.propertyBagObserver(calls, {
+  return () {
+    return { value: 5, done: true };
+  },
+}, "originalIter");
+
+const wrapper = Iterator.from(iter);
+assert.compareArray(calls, [
+  "get originalIter[Symbol.iterator]",
+  "get originalIter.next",
+]);
+
+wrapper.return();
+assert.compareArray(calls, [
+  "get originalIter[Symbol.iterator]",
+  "get originalIter.next",
+  "get originalIter.return"
+]);

test/built-ins/Iterator/from/return-method-calls-base-return-method.js

@@ -0,0 +1,41 @@
+// Copyright (C) 2024 Sosuke Suzuki. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-iterator.from
+description: >
+  %WrapForValidIteratorPrototype%.return() call base iterator's return method when it exists.
+info: |
+  %WrapForValidIteratorPrototype%.return ( )
+    5. Let returnMethod be ? GetMethod(iterator, "return").
+    6. If returnMethod is undefined, then
+      ...
+    7. Return ? Call(returnMethod, iterator).
+
+features: [iterator-helpers]
+includes: [temporalHelpers.js, compareArray.js]
+---*/
+
+const calls = [];
+
+const expectedIteratorResult = { value: 5, done: true };
+const originalIter = {
+    return () {
+        return expectedIteratorResult;
+    },
+};
+TemporalHelpers.observeMethod(calls, originalIter, "return", "originalIter");
+const iter = TemporalHelpers.propertyBagObserver(calls, originalIter, "originalIter");
+
+const wrapper = Iterator.from(iter);
+assert.compareArray(calls, [
+  "get originalIter[Symbol.iterator]",
+  "get originalIter.next",
+]);
+
+assert.sameValue(wrapper.return(), expectedIteratorResult);
+assert.compareArray(calls, [
+  "get originalIter[Symbol.iterator]",
+  "get originalIter.next",
+  "get originalIter.return",
+  "call originalIter.return",
+]);

test/built-ins/Iterator/from/return-method-returns-iterator-result.js

@@ -0,0 +1,23 @@
+// Copyright (C) 2024 Sosuke Suzuki. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-iterator.from
+description: >
+  %WrapForValidIteratorPrototype%.return() should return an iterator result object that value is undefined when base object does not have return method.
+info: |
+  %WrapForValidIteratorPrototype%.return ( )
+    ...
+    5. Let returnMethod be ? GetMethod(iterator, "return").
+    6. If returnMethod is undefined, then
+      a. Return CreateIterResultObject(undefined, true).
+
+features: [iterator-helpers]
+---*/
+
+const iter = {};
+const wrapper = Iterator.from(iter);
+
+const result = wrapper.return();
+assert(result.hasOwnProperty("value"));
+assert.sameValue(result.value, undefined);
+assert.sameValue(result.done, true);

test/built-ins/Iterator/from/return-method-throws-for-invalid-this.js

@@ -0,0 +1,39 @@
+// Copyright (C) 2024 Sosuke Suzuki. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-iterator.from
+description: >
+  %WrapForValidIteratorPrototype%.return() requires [[iterated]] internal slot
+info: |
+  %WrapForValidIteratorPrototype%.return ( )
+    ...
+    2. Perform ? RequireInternalSlot(O, [[Iterated]]).
+
+features: [iterator-helpers]
+includes: [temporalHelpers.js, compareArray.js]
+---*/
+
+const WrapForValidIteratorPrototype = Object.getPrototypeOf(Iterator.from({}));
+
+{
+  assert.throws(TypeError, function() {
+      WrapForValidIteratorPrototype.return.call({});
+  });
+}
+
+{
+  const originalIter = {
+    return() {
+      return { value: 5, done: true };
+    },
+  };
+
+  const calls = [];
+  TemporalHelpers.observeMethod(calls, originalIter, "return", "originalIter");
+  const iter = TemporalHelpers.propertyBagObserver(calls, originalIter, "originalIter");
+
+  assert.throws(TypeError, function() {
+      WrapForValidIteratorPrototype.return.call(iter);
+  });
+  assert.compareArray(calls, []);
+}