Stopwatch: Adds tests for TimerResetButton

src/components/timerResetButton/TimerResetButton.test.js

@@ -0,0 +1,56 @@
+import React from 'react'
+import { fireEvent, render, screen } from '@testing-library/react';
+import TimerResetButton from './TimerResetButton';
+
+const stubSetElapsedTime = jest.fn();
+const stubSetIsRunning = jest.fn();
+const stubUseContext = jest.fn();
+
+const defaultContext = {
+    isRunning: false,
+    setElapsedTime: stubSetElapsedTime,
+    setIsRunning: stubSetIsRunning
+}
+
+const renderWithContext = (context = defaultContext) => {
+    React.useContext = stubUseContext.mockReturnValue(context)
+    return render(<TimerResetButton/>)
+};
+
+beforeEach(() => {
+    jest.useFakeTimers();
+})
+
+afterEach(() => {
+    jest.useRealTimers();
+});
+
+test('should render as expected', () => {
+const component = renderWithContext();
+
+    expect(component.container).toMatchSnapshot();
+});
+
+test('should call setElapsedTime with expected parameters on button click', () => {
+    renderWithContext();
+
+    const button = screen.getByText('Reset');
+
+    fireEvent.click(button)
+
+    jest.runAllTimers();
+
+    expect(stubSetElapsedTime).toHaveBeenCalledWith(0);
+});
+
+test('should call setIsRunning with expected parameters on button click', () => {
+    renderWithContext();
+
+    const button = screen.getByText('Reset');
+
+    fireEvent.click(button)
+
+    jest.runAllTimers();
+
+    expect(stubSetIsRunning).toHaveBeenCalledWith(false);
+});

src/components/timerResetButton/__snapshots__/TimerResetButton.test.js.snap

@@ -0,0 +1,12 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`should render as expected 1`] = `
+<div>
+  <button
+    class="button"
+    id="stopwatch-reset"
+  >
+    Reset
+  </button>
+</div>
+`;