Implemented some debugging methods.

dwds/lib/src/servers/extension_debugger.dart

@@ -66,52 +66,70 @@ class ExtensionDebugger implements WipDebugger {
   }
 
   @override
-  Future disable() => throw UnimplementedError();
+  Future disable() => sendCommand('Debugger.disable');
 
   @override
-  Future enable() => throw UnimplementedError();
+  Future enable() => sendCommand('Debugger.enable');
 
   @override
-  Stream<T> eventStream<T>(String method, WipEventTransformer<T> transformer) =>
-      throw UnimplementedError();
+  Future<String> getScriptSource(String scriptId) async =>
+      (await sendCommand('Debugger.getScriptSource',
+              params: {'scriptId': scriptId}))
+          .result['scriptSource'] as String;
 
   @override
-  Future<String> getScriptSource(String scriptId) => throw UnimplementedError();
+  Future pause() => sendCommand('Debugger.pause');
 
   @override
-  Stream<WipDomain> get onClosed => throw UnimplementedError();
+  Future resume() => sendCommand('Debugger.resume');
 
   @override
-  Stream<GlobalObjectClearedEvent> get onGlobalObjectCleared =>
-      throw UnimplementedError();
+  Future setPauseOnExceptions(PauseState state) =>
+      sendCommand('Debugger.setPauseOnExceptions',
+          params: {'state': _pauseStateToString(state)});
 
   @override
-  Stream<DebuggerPausedEvent> get onPaused => throw UnimplementedError();
+  Future stepInto() => sendCommand('Debugger.stepInto');
 
   @override
-  Stream<DebuggerResumedEvent> get onResumed => throw UnimplementedError();
+  Future stepOut() => sendCommand('Debugger.stepOut');
 
   @override
-  Stream<ScriptParsedEvent> get onScriptParsed => throw UnimplementedError();
+  Future stepOver() => sendCommand('Debugger.stepOver');
 
   @override
-  Future pause() => throw UnimplementedError();
+  Stream<T> eventStream<T>(String method, WipEventTransformer<T> transformer) =>
+      throw UnimplementedError();
 
   @override
-  Future resume() => throw UnimplementedError();
+  Stream<WipDomain> get onClosed => throw UnimplementedError();
 
   @override
-  Map<String, WipScript> get scripts => throw UnimplementedError();
+  Stream<GlobalObjectClearedEvent> get onGlobalObjectCleared =>
+      throw UnimplementedError();
 
   @override
-  Future setPauseOnExceptions(PauseState state) => throw UnimplementedError();
+  Stream<DebuggerPausedEvent> get onPaused => throw UnimplementedError();
 
   @override
-  Future stepInto() => throw UnimplementedError();
+  Stream<DebuggerResumedEvent> get onResumed => throw UnimplementedError();
 
   @override
-  Future stepOut() => throw UnimplementedError();
+  Stream<ScriptParsedEvent> get onScriptParsed => throw UnimplementedError();
 
   @override
-  Future stepOver() => throw UnimplementedError();
+  Map<String, WipScript> get scripts => throw UnimplementedError();
+
+  String _pauseStateToString(PauseState state) {
+    switch (state) {
+      case PauseState.all:
+        return 'all';
+      case PauseState.none:
+        return 'none';
+      case PauseState.uncaught:
+        return 'uncaught';
+      default:
+        throw ArgumentError('unknown state: $state');
+    }
+  }
 }

dwds/test/extension_debugger_test.dart

@@ -22,7 +22,7 @@ void main() async {
     extensionDebugger = ExtensionDebugger(connection);
   });
 
-  test('can send a command & receive a response', () async {
+  test('can receive a response', () async {
     var extensionResponse = ExtensionResponse((b) => b
       ..result = jsonEncode({
         'result': {'value': 3.14}
@@ -34,9 +34,19 @@ void main() async {
         params: {'expression': '\$pi'}).then((response) {
       resultCompleter.complete(response);
     }));
-    connection.controller
+    connection.controllerIncoming.sink
         .add(jsonEncode(serializers.serialize(extensionResponse)));
     var response = await resultCompleter.future;
     expect(response.result['value'], 3.14);
   });
+
+  test('can send a request', () async {
+    var extensionRequest = ExtensionRequest((b) => b
+      ..id = 0
+      ..command = 'Debugger.pause');
+    unawaited(extensionDebugger.pause());
+    var request = serializers.deserialize(
+        jsonDecode(await connection.controllerOutgoing.stream.first));
+    expect(request, extensionRequest);
+  });
 }

dwds/test/fixtures/fakes.dart

@@ -100,9 +100,11 @@ class FakeSseConnection implements SseConnection {
   @override
   StreamChannel<S> cast<S>() => null;
 
-  final _controller = StreamController<String>();
+  /// A [StreamController] for incoming messages on SSE connection.
+  final controllerIncoming = StreamController<String>();
 
-  StreamController<String> get controller => _controller;
+  /// A [StreamController] for outgoing messages on SSE connection.
+  final controllerOutgoing = StreamController<String>();
 
   @override
   StreamChannel<String> changeSink(
@@ -118,10 +120,10 @@ class FakeSseConnection implements SseConnection {
   void pipe(StreamChannel<String> other) {}
 
   @override
-  StreamSink<String> get sink => controller.sink;
+  StreamSink<String> get sink => controllerOutgoing.sink;
 
   @override
-  Stream<String> get stream => controller.stream;
+  Stream<String> get stream => controllerIncoming.stream;
 
   @override
   StreamChannel<S> transform<S>(