Bug 1360839 - Call IteratorClose due to abrupt completion from yield

Issue #74

1 files changed, 58 insertions, 0 deletions

diff --git a/js/src/tests/ecma_6/Generators/yield-iterator-close.js b/js/src/tests/ecma_6/Generators/yield-iterator-close.js
new file mode 100644
index 0000000000..970ad494d2
--- /dev/null
+++ b/js/src/tests/ecma_6/Generators/yield-iterator-close.js
@@ -0,0 +1,58 @@
+// Test that IteratorClose is called when a Generator is abruptly completed by
+// Generator.return.
+
+var returnCalled = 0;
+function* wrapNoThrow() {
+  let iter = {
+    [Symbol.iterator]() {
+      return this;
+    },
+    next() {
+      return { value: 10, done: false };
+    },
+    return() {
+      returnCalled++;
+      return {};
+    }
+  };
+  for (const i of iter) {
+    yield i;
+  }
+}
+
+// Breaking calls Generator.return, which causes the yield above to resume with
+// an abrupt completion of kind "return", which then calls
+// iter.return.
+for (const i of wrapNoThrow()) {
+  break;
+}
+assertEq(returnCalled, 1);
+
+function* wrapThrow() {
+  let iter = {
+    [Symbol.iterator]() {
+      return this;
+    },
+    next() {
+      return { value: 10, done: false };
+    },
+    return() {
+      throw 42;
+    }
+  };
+  for (const i of iter) {
+    yield i;
+  }
+}
+
+// Breaking calls Generator.return, which, like above, calls iter.return. If
+// iter.return throws, since the yield is resuming with an abrupt completion of
+// kind "return", the newly thrown value takes precedence over returning.
+assertThrowsValue(() => {
+  for (const i of wrapThrow()) {
+    break;
+  }
+}, 42);
+
+if (typeof reportCompare === "function")
+  reportCompare(0, 0);