Use messages for (some) public API errors

pkg/front_end/test/kernel_generator_test.dart

Index: pkg/front_end/test/kernel_generator_test.dart
diff --git a/pkg/front_end/test/kernel_generator_test.dart b/pkg/front_end/test/kernel_generator_test.dart
index 831dbaf63c5988368269709197a62acb67955afe..1e773fbdbbe4113c51181b896d2206b332325664 100644
--- a/pkg/front_end/test/kernel_generator_test.dart
+++ b/pkg/front_end/test/kernel_generator_test.dart
@@ -56,16 +56,18 @@ main() {
       var errors = [];
       var options = new CompilerOptions()..onError = (e) => errors.add(e);
       await compileScript('a() => print("hi");', options: options);
-      expect('${errors.first}', contains("No 'main' method found"));
+      // TODO(sigmund): when we expose codes in the public APIs, we should
+      // compare the code here and not the message.
+      expect(errors.first.message, contains("No 'main' method found"));

[ahe, 2017/07/13 00:03:38]

I think this might work:

equals(messageMissingMain.message)

[Siggi Cherem (dart-lang), 2017/07/18 00:32:57]

Done.

     });
 
     test('default error handler throws', () async {
       var exceptionThrown = false;
       try {
         await compileScript('a() => print("hi");');
-      } catch (e) {
+      } on CompilationError catch (e) {
         exceptionThrown = true;
-        expect('$e', contains("No 'main' method found"));
+        expect(e.message, contains("No 'main' method found"));
       }
       expect(exceptionThrown, isTrue);
     });
@@ -146,7 +148,7 @@ main() {
         'b.dart': ''
       };
       await compileUnit(['a.dart'], sources, options: options);
-      expect(errors.first.toString(), contains('Invalid access'));
+      expect(errors.first.message, contains('Invalid access'));
       errors.clear();
 
       await compileUnit(['a.dart', 'b.dart'], sources, options: options);