diff --git a/jest.config.js b/jest.config.js
index b0471e6..37c7c33 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -2,8 +2,12 @@ const jestJupyterLab = require('@jupyterlab/testutils/lib/jest-config');
 
 const esModules = [
   '@codemirror',
+  '@microsoft',
+  '@jupyter/react-components',
+  '@jupyter/web-components',
   '@jupyter/ydoc',
   '@jupyterlab/',
+  'exenv-es6',
   'lib0',
   'nanoid',
   'vscode-ws-jsonrpc',
diff --git a/src/__tests__/jupyter-chat.spec.ts b/src/__tests__/jupyter-chat.spec.ts
deleted file mode 100644
index 3f469ed..0000000
--- a/src/__tests__/jupyter-chat.spec.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-/**
- * Example of [Jest](https://jestjs.io/docs/getting-started) unit tests
- */
-
-describe('@jupyter/chat', () => {
-  it('should be tested', () => {
-    expect(1 + 1).toEqual(2);
-  });
-});
diff --git a/src/__tests__/model.spec.ts b/src/__tests__/model.spec.ts
new file mode 100644
index 0000000..42a2759
--- /dev/null
+++ b/src/__tests__/model.spec.ts
@@ -0,0 +1,84 @@
+/**
+ * Example of [Jest](https://jestjs.io/docs/getting-started) unit tests
+ */
+
+import { ChatModel, IChatModel } from '../model';
+import { IChatMessage, IMessage } from '../types';
+
+describe('test chat model', () => {
+  describe('model instantiation', () => {
+    it('should create a ChatModel', () => {
+      const model = new ChatModel();
+      expect(model).toBeInstanceOf(ChatModel);
+    });
+
+    it('should dispose a ChatModel', () => {
+      const model = new ChatModel();
+      model.dispose()
+      expect(model.isDisposed).toBeTruthy();
+    });
+  });
+
+  describe('incoming message', () => {
+    class TestChat extends ChatModel {
+      protected formatChatMessage(message: IChatMessage): IChatMessage {
+        message.body = 'formatted msg';
+        return message;
+      }
+    };
+
+    let model: IChatModel;
+    let messages: IMessage[];
+    const msg = {
+      type: 'msg',
+      id: 'message1',
+      time: Date.now() / 1000,
+      body: 'message test',
+      sender: { id: 'user'}
+    } as IChatMessage;
+
+    beforeEach(() => {
+      messages = [];
+    })
+
+    it('should signal incoming message', () => {
+      model = new ChatModel();
+      model.incomingMessage.connect(
+        (sender: IChatModel, message: IMessage) => {
+          expect(sender).toBe(model);
+          messages.push(message);
+        }
+      );
+      model.onMessage(msg);
+      expect(messages).toHaveLength(1);
+      expect(messages[0]).toBe(msg);
+    });
+
+    it('should format message', () => {
+      model = new TestChat();
+      model.incomingMessage.connect(
+        (sender: IChatModel, message: IMessage) => {
+          expect(sender).toBe(model);
+          messages.push(message);
+        }
+      );
+      model.onMessage({...msg} as IChatMessage);
+      expect(messages).toHaveLength(1);
+      expect(messages[0]).not.toBe(msg);
+      expect((messages[0] as IChatMessage).body).toBe('formatted msg');
+    })
+
+  })
+
+  describe('model config', () => {
+    it('should have empty config', () => {
+      const model = new ChatModel();
+      expect(model.config.sendWithShiftEnter).toBeUndefined();
+    });
+
+    it('should allow config', () => {
+      const model = new ChatModel({config: {sendWithShiftEnter: true}});
+      expect(model.config.sendWithShiftEnter).toBeTruthy();
+    });
+  })
+});
diff --git a/src/__tests__/widgets.spec.ts b/src/__tests__/widgets.spec.ts
new file mode 100644
index 0000000..31997e7
--- /dev/null
+++ b/src/__tests__/widgets.spec.ts
@@ -0,0 +1,35 @@
+/**
+ * Example of [Jest](https://jestjs.io/docs/getting-started) unit tests
+ */
+
+import { IRenderMimeRegistry, RenderMimeRegistry } from "@jupyterlab/rendermime";
+import { ChatModel, IChatModel } from "../model";
+import { ChatWidget } from "../widgets/chat-widget";
+
+describe('test chat widget', () => {
+  let model: IChatModel;
+  let rmRegistry: IRenderMimeRegistry;
+
+  beforeEach(() => {
+    model = new ChatModel();
+    rmRegistry = new RenderMimeRegistry();
+  })
+
+  describe('model instantiation', () => {
+    it('should create a ChatModel', () => {
+      const widget = new ChatWidget({ model, rmRegistry });
+      expect(widget).toBeInstanceOf(ChatWidget);
+    });
+
+    it('should dispose a ChatModel', () => {
+      const widget = new ChatWidget({ model, rmRegistry });
+      widget.dispose()
+      expect(widget.isDisposed).toBeTruthy();
+    });
+
+    it('should provides the model', () => {
+      const widget = new ChatWidget({ model, rmRegistry });
+      expect(widget.model).toBe(model);
+    });
+  });
+});
diff --git a/src/components/chat.tsx b/src/components/chat.tsx
index b929a9e..9010793 100644
--- a/src/components/chat.tsx
+++ b/src/components/chat.tsx
@@ -96,9 +96,8 @@ export function Chat(props: Chat.IOptions): JSX.Element {
   const [view, setView] = useState<Chat.ChatView>(
     props.chatView || Chat.ChatView.Chat
   );
-  console.log('Instantiate a chat');
   return (
-    <JlThemeProvider themeManager={props.themeManager}>
+    <JlThemeProvider themeManager={props.themeManager ?? null}>
       <Box
         // root box should not include padding as it offsets the vertical
         // scrollbar to the left
@@ -152,14 +151,14 @@ export namespace Chat {
      * The chat model.
      */
     model: IChatModel;
-    /**
-     * The theme manager.
-     */
-    themeManager: IThemeManager | null;
     /**
      * The rendermime registry.
      */
     rmRegistry: IRenderMimeRegistry;
+    /**
+     * The theme manager.
+     */
+    themeManager?: IThemeManager | null;
     /**
      * The view to render.
      */
diff --git a/src/widgets/chat-widget.tsx b/src/widgets/chat-widget.tsx
index 755662a..9a0060a 100644
--- a/src/widgets/chat-widget.tsx
+++ b/src/widgets/chat-widget.tsx
@@ -15,7 +15,7 @@ export class ChatWidget extends ReactWidget {
     this.title.caption = 'Jupyter Chat'; // TODO: i18n
 
     this._model = options.model;
-    this._themeManager = options.themeManager;
+    this._themeManager = options?.themeManager || null;
     this._rmRegistry = options.rmRegistry;
   }