Java: Using Mockito for Unit Testing

ProgrammableTest.java

package us.home.electronics;

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import org.junit.Test;

public class ProgrammableTest {

	@Test
	public void testBeepBeep() throws Exception {
		Programmable clock = new Programmable.AlarmClock();
		Programmable.ProgramCoder coder = mock(Programmable.ProgramCoder.class);

		// this line 'overrides' the ProgramCoder.getProgramcode() method
		when(coder.getProgramCode()).thenReturn("Beep Beep");

		clock.programDevice(coder);

		assertEquals("Beep Beep", clock.execute());
		assertEquals(clock.getCode(), clock.execute());
	}
}