Merge two language/scope_ tests

tests/language/scope_variable_test.dart

 // Copyright (c) 2011, 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.
 
 import "package:expect/expect.dart";
 
-class ScopeVariableTest {
+void testSimpleScope() {
+  {
+    var a = "Test";
+    int b = 1;
+  }
+  {
+    var c;
+    int d;
+    Expect.equals(true, c == null);

[kustermann, 2013/09/04 09:28:42]

I'd use one of these two instead:

  Expect.isTrue(c == null)
  Expect.equals(null, c)

It's kind of strange to do 'Expect.equals(true, c == null)'.

[Søren Gjesse, 2013/09/04 10:16:16]

Done (I just copied some old code). Ended up using Expect.isNull.

[kustermann, 2013/09/04 10:19:16]

'Expect.isNull' is even better in this case.

My comment was ment to be general: a few lines down we've the same
'Expect.equals()'.

+    Expect.equals(true, d == null);
+    }
+}
 
-  static void testSimpleScope() {
-    {
-      var a = "Test";
-      int b = 1;
-    }
-    {
-      var c;
-      int d;
-      Expect.equals(true, c == null);
-      Expect.equals(true, d == null);
-    }
+void testShadowingScope() {
+  var a = "Test";
+  {
+    var a;
+    Expect.equals(true, a == null);
+    a = "a";
+    Expect.equals(true, a == "a");
   }
+  Expect.equals(true, a == "Test");
+}
 
-  static void testShadowingScope() {
-    var a = "Test";
-    {
-      var a;
-      Expect.equals(true, a == null);
-      a = "a";
-      Expect.equals(true, a == "a");
-    }
-    Expect.equals(true, a == "Test");
-  }
-
-  static void testMain() {
-    testSimpleScope();
-    testShadowingScope();
+int testShadowingAfterUse() {
+  var a = 1;
+  {
+    var b = 2;
+    var c = a;  // Use of 'a' prior to its shadow declaration below.
+    var d = b + c;
+    // Shadow declaration of 'a'.
+    var a = 5;  /// 01: compile-time error

[kustermann, 2013/09/04 09:28:42]

I wasn't aware that this is supposed to result in a compile-time error.
Good to know!

+    return d + a;
   }
 }
 
 main() {
-  ScopeVariableTest.testMain();
+  testSimpleScope();
+  testShadowingScope();
+  testShadowingAfterUse();
 }