Validate the regex used in search.findTopLevelDeclarations.

pkg/analysis_server/test/search/top_level_declarations_test.dart

Index: pkg/analysis_server/test/search/top_level_declarations_test.dart
diff --git a/pkg/analysis_server/test/search/top_level_declarations_test.dart b/pkg/analysis_server/test/search/top_level_declarations_test.dart
index 81fa08b749478c62191201a78d2db826a4988f2f..8b1829c8e2e7a7af7e115e8e8f1febd268c75241 100644
--- a/pkg/analysis_server/test/search/top_level_declarations_test.dart
+++ b/pkg/analysis_server/test/search/top_level_declarations_test.dart
@@ -39,6 +39,9 @@ class TopLevelDeclarationsTest extends AbstractSearchDomainTest {
     Request request =
         new SearchFindTopLevelDeclarationsParams(pattern).toRequest('0');
     Response response = await waitResponse(request);
+    if (response.error != null) {
+      return response.error;
+    }
     searchId =
         new SearchFindTopLevelDeclarationsResult.fromResponse(response).id;
     return waitForSearchResults();
@@ -71,4 +74,9 @@ class ABC {}
     assertHasDeclaration(ElementKind.TOP_LEVEL_VARIABLE, 'E');
     assertNoDeclaration(ElementKind.CLASS, 'ABC');
   }
+
+  test_invalidRegex() async {
+    var result = await findTopLevelDeclarations('[A');
+    expect(result, new isInstanceOf<RequestError>());
+  }
 }