Add integration tests for the execution domain.

pkg/analyzer_plugin/test/integration/support/integration_tests.dart

Index: pkg/analyzer_plugin/test/integration/support/integration_tests.dart
diff --git a/pkg/analyzer_plugin/test/integration/support/integration_tests.dart b/pkg/analyzer_plugin/test/integration/support/integration_tests.dart
index 46200d4236bea66e5a1bd97cf38437da831e0681..80c7a2041abb0630a90435cec030858b5ea51ace 100644
--- a/pkg/analyzer_plugin/test/integration/support/integration_tests.dart
+++ b/pkg/analyzer_plugin/test/integration/support/integration_tests.dart
@@ -261,6 +261,17 @@ abstract class AbstractAnalysisServerIntegrationTest
 }
 
 /**
+ * An error result from a server request.
+ */
+class ServerErrorMessage {
+  final Map message;
+
+  ServerErrorMessage(this.message);
+
+  dynamic get error => message['error'];
+}
+
+/**
  * Wrapper class for Matcher which doesn't create the underlying Matcher object
  * until it is needed.  This is necessary in order to create matchers that can
  * refer to themselves (so that recursive data structures can be represented).
@@ -558,9 +569,7 @@ class Server {
           _pendingCommands.remove(id);
         }
         if (messageAsMap.containsKey('error')) {
-          // TODO(paulberry): propagate the error info to the completer.
-          completer.completeError(new UnimplementedError(
-              'Server responded with an error: ${JSON.encode(message)}'));
+          completer.completeError(new ServerErrorMessage(messageAsMap));
         } else {
           completer.complete(messageAsMap['result']);
         }