1 files changed, 116 insertions, 0 deletions
diff --git a/js/src/tests/non262/statements/for-of-async-of-starting-lhs.js b/js/src/tests/non262/statements/for-of-async-of-starting-lhs.js
new file mode 100644
index 0000000000..eba66679a3
--- /dev/null
+++ b/js/src/tests/non262/statements/for-of-async-of-starting-lhs.js
@@ -0,0 +1,116 @@
+if (typeof getRealmConfiguration === "undefined") {
+  var getRealmConfiguration = SpecialPowers.Cu.getJSTestingFunctions().getRealmConfiguration;
+}
+
+const IsTopLevelAwaitEnabled = getRealmConfiguration().topLevelAwait;
+
+const AsyncFunction = async function(){}.constructor;
+
+function assertNoError(f, msg) {
+  try {
+    f();
+  } catch (e) {
+    assertEq(true, false, `${msg}: ${e}`);
+  }
+}
+
+function assertSyntaxError(code) {
+  assertThrowsInstanceOf(function () { Function(code); }, SyntaxError, "Function:" + code);
+  assertThrowsInstanceOf(function () { AsyncFunction(code); }, SyntaxError, "AsyncFunction:" + code);
+
+  if (typeof parseModule === "function") {
+    assertThrowsInstanceOf(function () { parseModule(code); }, SyntaxError, "Module:" + code);
+  }
+}
+
+function assertNoSyntaxError(code) {
+  assertNoError(function () { Function(code); }, "Function:" + code);
+  assertNoError(function () { AsyncFunction(code); }, "AsyncFunction:" + code);
+
+  if (typeof parseModule === "function") {
+    assertNoError(function () { parseModule(code); }, "Module:" + code);
+  }
+}
+
+function assertNoSyntaxErrorAsyncContext(code) {
+  assertNoError(function () { AsyncFunction(code); }, "AsyncFunction:" + code);
+
+  if (typeof parseModule === "function" && IsTopLevelAwaitEnabled) {
+    assertNoError(function () { parseModule(code); }, "Module:" + code);
+  }
+}
+
+const invalidTestCases = [
+  // for-in loop: LHS can't start with an async arrow function.
+  "for ( async of => {} in [] ) ;",
+  "for ( async o\\u0066 => {} in [] ) ;",
+
+  // for-of loop: LHS can't start with an async arrow function.
+  "for ( async of => {} of [] ) ;",
+  "for ( async o\\u0066 => {} of [] ) ;",
+
+  // for-of loop: LHS can't start with an identifier named "async".
+  "for ( async of [] ) ;",
+
+  // for-await-of loop: LHS can't start with an async arrow function.
+  "for await ( async of => {} of [] ) ;",
+  "for await ( async o\\u0066 => {} of [] ) ;",
+];
+
+for (let source of invalidTestCases) {
+  assertSyntaxError(source);
+
+  // Also test when the tokens are separated by newline characters.
+  assertSyntaxError(source.split(" ").join("\n"));
+}
+
+// for-loop: async arrow functions are allowed in C-style for-loops.
+assertNoSyntaxError("for ( async of => {} ; ; ) ;")
+
+const validTestCases = [
+  // for-loop: LHS can start with an identifier named "async".
+  "for ( async ; ; ) ;",
+  "for ( \\u0061sync ; ; ) ;",
+
+  // for-in loop: LHS can start with an identifier named "async".
+  "for ( async in [] ) ;",
+  "for ( \\u0061sync in [] ) ;",
+
+  // for-in loop: LHS can start with an property assignment starting with "async".
+  "for ( async . prop in [] ) ;",
+  "for ( async [ 0 ] in [] ) ;",
+
+  // for-of loop: LHS can start with an identifier named "async" when escape characters are used.
+  "for ( \\u0061sync of [] ) ;",
+
+  // for-of loop: LHS can start with an property assignment starting with "async".
+  "for ( async . prop of [] ) ;",
+  "for ( async [ 0 ] of [] ) ;",
+];
+
+for (let source of validTestCases) {
+  assertNoSyntaxError(source);
+
+  // Also test when the tokens are separated by newline characters.
+  assertNoSyntaxError(source.split(" ").join("\n"));
+}
+
+const validTestCasesAsync = [
+  // for-await-of loop: LHS can start with an identifier named "async".
+  "for await ( async of [] ) ;",
+  "for await ( \\u0061sync of [] ) ;",
+
+  // for-await-of loop: LHS can start with an property assignment starting with "async".
+  "for await ( async . prop of [] ) ;",
+  "for await ( async [ 0 ] of [] ) ;",
+];
+
+for (let source of validTestCasesAsync) {
+  assertNoSyntaxErrorAsyncContext(source);
+
+  // Also test when the tokens are separated by newline characters.
+  assertNoSyntaxErrorAsyncContext(source.split(" ").join("\n"));
+}
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);