feature: add sample tests

__tests__/actions/Todo.test.js

@@ -0,0 +1,28 @@
+import configureStore from 'redux-mock-store';
+
+import { ADD_TODO } from '../../app/constants/actions';
+
+import { addTodo } from '../../app/actions/add-todo';
+
+const store = configureStore()();
+
+describe('Todo Actions', () => {
+  beforeEach(() => store.clearActions());
+
+  test('should create an action to add a new todo', () => {
+    const text = 'Hello World!';
+
+    store.dispatch(addTodo(text));
+    expect(store.getActions()[0]).toEqual(
+      expect.objectContaining({
+        type: ADD_TODO,
+        payload: {
+          text,
+          id: expect.any(String),
+          editing: false,
+          createdAt: expect.any(Number),
+        },
+      }),
+    );
+  });
+});

__tests__/components/Sidebar.test.js

@@ -0,0 +1,16 @@
+import React from 'react';
+import { shallow } from 'enzyme';
+import toJson from 'enzyme-to-json';
+
+import { SidebarComponent } from '../../app/components/sidebar/index';
+
+describe('<Sidebar />', () => {
+  describe('render()', () => {
+    test('should render correctly', () => {
+      const wrapper = shallow(<SidebarComponent />);
+      const component = wrapper.dive();
+
+      expect(toJson(component)).toMatchSnapshot();
+    });
+  });
+});

__tests__/components/__snapshots__/Sidebar.test.js.snap

@@ -0,0 +1,69 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`<Sidebar /> render() should render correctly 1`] = `
+<StyledComponent
+  forwardedClass={
+    Object {
+      "$$typeof": Symbol(react.forward_ref),
+      "attrs": Array [],
+      "componentStyle": ComponentStyle {
+        "componentId": "sc-bdVaJa",
+        "isStatic": true,
+        "rules": Array [
+          "
+  ",
+          "
+    display: flex;
+    flex-direction: column;
+    width: 200px;
+    position: absolute;
+    left: 0;
+    top: 0;
+    height: 100vh;
+    background: #ccc;
+  ",
+          "
+",
+        ],
+      },
+      "displayName": "styled.div",
+      "render": [Function],
+      "styledComponentId": "sc-bdVaJa",
+      "target": "div",
+      "toString": [Function],
+      "warnTooManyClasses": [Function],
+      "withComponent": [Function],
+    }
+  }
+  forwardedRef={null}
+>
+  <Link
+    key="/"
+    replace={false}
+    to="/"
+  >
+    Dashboard
+  </Link>
+  <Link
+    key="/send"
+    replace={false}
+    to="/send"
+  >
+    Send
+  </Link>
+  <Link
+    key="/receive"
+    replace={false}
+    to="/receive"
+  >
+    Receive
+  </Link>
+  <Link
+    key="/settings"
+    replace={false}
+    to="/settings"
+  >
+    Settings
+  </Link>
+</StyledComponent>
+`;

__tests__/reducers/Todo.test.js

@@ -0,0 +1,26 @@
+import todoReducer from '../../app/reducers/todo';
+import { ADD_TODO } from '../../app/constants/actions';
+
+describe('Todo Reducer', () => {
+  test('should return the valid initial state', () => {
+    const action = { type: 'UNKNOWN_ACTION' };
+    const initialState = [];
+
+    expect(todoReducer(undefined, action)).toEqual(initialState);
+  });
+
+  test('should add a new todo', () => {
+    const action = {
+      type: ADD_TODO,
+      payload: {
+        id: 'abc123',
+        text: 'Hello World!',
+        editing: false,
+        createdAt: new Date().getTime(),
+      },
+    };
+    const expectedState = [action.payload];
+
+    expect(todoReducer(undefined, action)).toEqual(expectedState);
+  });
+});