Syntax tests for disabled variance flag.

Change-Id: I796db1ce44b37e65bd4633abb962004a6e079041
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/117288
Reviewed-by: Leaf Petersen <[email protected]>
Commit-Queue: Kallen Tu <[email protected]>

Author: kallentu

tests/language_2/variance/syntax/variance_disabled_syntax_test.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests that since `variance` flag is disabled, correct variance modifier usage will issue an error.
+
+class A<in X> {}
+//      ^^
+// [analyzer] COMPILE_TIME_ERROR.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME
+// [cfe] Expected an identifier, but got 'in'.
+//      ^^
+// [analyzer] SYNTACTIC_ERROR.MISSING_IDENTIFIER
+//         ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
+// [cfe] Expected ',' before this.
+
+class B<out X, in Y, inout Z> {}
+//          ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
+// [cfe] Expected ',' before this.
+//             ^^
+// [analyzer] COMPILE_TIME_ERROR.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME
+// [cfe] Expected an identifier, but got 'in'.
+//             ^^
+// [analyzer] SYNTACTIC_ERROR.MISSING_IDENTIFIER
+//                ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
+// [cfe] Expected ',' before this.
+//                         ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
+// [cfe] Expected ',' before this.
+
+mixin C<inout T> {}
+//            ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
+// [cfe] Expected ',' before this.
+
+typedef D<out T> = T Function();
+//            ^
+// [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
+// [cfe] Expected ',' before this.

tests/language_2/variance/syntax/variance_keyword_identifier_syntax_test.dart

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+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests identifier usage of keywords `out` and `inout`, correct usage of `in`.
+
+import "package:expect/expect.dart";
+
+class OutParameter {
+  var out = 3;
+  int func(int out) {
+    return out;
+  }
+}
+
+class inout {
+  void out(int x) {}
+}
+
+var out = 5;
+
+main() {
+  OutParameter x = new OutParameter();
+  Expect.equals(2, x.func(2));
+  Expect.equals(3, x.out);
+
+  inout foo = inout();
+  foo.out(4);
+
+  Expect.equals(5, out);
+
+  var collection = [0, 1, 2];
+  for (var x in collection) {
+    Expect.isTrue(x is int);
+  }
+}