Junit & Mockito

Junit & Mockito

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Arjit Sharma
01 Min

JUnit

  • JUnit is a unit testing framework for Java and can be used for automation testing in CI/CD pipeline.
  • Junit methods - assertTrue(condn),assertFalse(condn),assertEquals(expected,actual),assertNull(),assertArrayEquals(expected,actual)
  • Junit annotations - @Test,@Before(runs before every test),@After,@BeforeClass,@AfterClass.

Example of JUnit

sampleTest.java

class sampleTest {
    @Test
	void test_for_both_positive() {
		sample s = new sample(); // we wanna test sample class's add method
		assertEquals(2,s.add(1,1));
	}
}

Mockito

  • How to test a piece of code without implementing and testing its dependencies.
  • Without mockito we will have to create a stub, but problem is for different cases we have to create different stubs hence Mockito is used.
  • Annotations provided are @RunWith(MockitoJUnitRunner.class), @Mock, @InjectMocks
  • Before looking at example, lets take a look at mocking a class’s function without annotations. Suppose class A’s AFunc is dependant on B(It has a function BFunc). Now instead of creating a stub(fake function within B) we can mock it using Mockito.
@Test
void Test(){
	B bmock = mock(B.class);
	when(bmock.BFunc()).thenReturn(new String("Hello")); //when this function is called return this value
	A a = new A(bmock); // injecting using constructor injection
	String result = a.AFunc();
	assertEquals(-2,res);
}

Example of Mockito -

We have Data which is dependent on DataService, so we mock DataService.

Data.java

public class Data {
	public DataService dataService;
	
	public Data(DataService dataService){
		this.dataService=dataService;
	}
	
	public int findGreatest() {
		int[] data = dataService.retrieveAllData();
		int greatest = Integer.MIN_VALUE;
		
		for(int i: data) 
			greatest = Math.max(greatest, i);
		
		return greatest;
	}
}

DataService.java

public interface DataService {
	int[] retrieveAllData();
}

testData.java

@RunWith(MockitoJUnitRunner.class)
class test_Data {
	@Mock
	DataService dataservicemock;

	@InjectMocks
	Data ob;

	@Test
	void test1() {
		when(dataservicemock.retrieveAllData()).thenReturn(new int[] {20,40,2,19});
		int res = ob.findGreatest();
		assertEquals(40,res);
	}
}

Code Link - Code link

References - Spring Master Class

Article by Arjit Sharma

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