diff --git a/jerry-debugger/src/lib/__tests__/debugger-client.test.ts b/jerry-debugger/src/lib/__tests__/debugger-client.test.ts
new file mode 100644
index 0000000000..8007ef67c0
--- /dev/null
+++ b/jerry-debugger/src/lib/__tests__/debugger-client.test.ts
@@ -0,0 +1,70 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import { JerryDebugger, DEFAULT_DEBUGGER_HOST, DEFAULT_DEBUGGER_PORT } from '../debugger-client';
+import WebSocket from 'ws';
+
+//const mockOn = jest.fn();
+jest.mock('ws', () => {
+  return jest.fn().mockImplementation(() => {
+    return {};
+  });
+});
+
+describe('JerryDebugger constructor', () => {
+  it ('uses supplied option values', () => {
+    const jd = new JerryDebugger({
+      host: '10.10.10.10',
+      port: 4096,
+      verbose: true,
+    });
+    expect(jd.host).toEqual('10.10.10.10');
+    expect(jd.port).toEqual(4096);
+    expect(jd.verbose).toEqual(true);
+  });
+
+  it('supplies option defaults when missing', () => {
+    const jd = new JerryDebugger({});
+    expect(jd.host).toEqual(DEFAULT_DEBUGGER_HOST);
+    expect(jd.port).toEqual(DEFAULT_DEBUGGER_PORT);
+    expect(jd.verbose).toEqual(false);
+  });
+});
+
+describe('JerryDebugger.connect', () => {
+  beforeEach(() => {
+  });
+
+  it('creates a websocket', () => {
+    const jd = new JerryDebugger({});
+    jd.connect();
+    expect(WebSocket).toHaveBeenCalledTimes(1);
+  });
+
+  it('returns a resolving promise when already connected', () => {
+    const jd = new JerryDebugger({});
+    jd.connect();
+    expect(WebSocket).toHaveBeenCalledTimes(1);
+    const p2 = jd.connect();
+    console.log('here1');
+    return expect(p2).resolves.toBe(undefined);
+  });
+
+  it('returned promise resolves when socket connects', () => {
+    const jd = new JerryDebugger({});
+    const p = jd.connect();
+    console.log('here2');
+    expect(p).resolves.toBe(undefined);
+  });
+});