Add tests for variable declarations

test/mjsunit/harmony/typesystem/testgen.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var debug = false;
 
-function CheckValid(type) {
-  if (debug) { print("V:", type); }
-  assertDoesNotThrow("'use types'; var x: " + type + ";");
+function CheckValid(script) {
+  if (debug) { print("V:", script); }
+  assertDoesNotThrow("'use types'; " + script);
 }
 
-function CheckInvalid(type) {
-  if (debug) { print("I:", type); }
-  assertThrows("'use types'; var x: " + type + ";", SyntaxError);
+function CheckInvalid(script, exception=SyntaxError) {
+  if (debug) { print("I:", script); }
+  assertThrows("'use types'; " + script, exception);
+}
+
+function CheckValidType(type) {
+  CheckValid("var x: " + type + ";");
+}
+
+function CheckInvalidType(type, exception=SyntaxError) {
+  CheckInvalid("var x: " + type + ";", exception);
 }
 
 // Parameters:
 //   multiplicity: positive integer
 //   generator: (size: positive integer, ...params: any[]) => Iterator<SomeType>
 //   transformations: [false | ((t: SomeType) => OtherType)]
 //   params: any[]
 //
 // A "test generator" object will have its "generator" generate tests,
 // will transform each generated test with all of its "transformations"
@@ skipping 83 matching lines @@
     }
   }
 }
 
 // Parameters:
 //   size:       positive integer
 //   generators: [string | TestGen]
 //
 // This function will generate all tests yielded by Generate and will
 // discard the results.  It will normally be called with test generators
-// whose transformation functions test for validity (e.g. CheckValid or
-// CheckInvalid) and do not return anything interesting.
+// whose transformation functions test for validity (e.g. CheckValidType
+// or CheckInvalidType) and do not return anything interesting.
 function Test(size, generators) {
   for (let attempt of Generate(size, generators)) continue;
 }