JUnit, Mockito, Hamcrest, Powermock & Jacoco, SonarQube

Challenges with UI/Service testing

• Complete application setup required along with external dependencies
• Root cause analysis takes more time as the analysis require from UI, BD & Code

Junits

• Method/group of methods
• Easy to debug
• Fast

Java 8 - Junit5

Junit

• Assert an Exception
• @Test(expected = IllegalArgumentException.class)
•  
   
  

 

Vocabulary

• SUT - SystemUnderTest is the code to write unit tests for
• Stub 
• Maintenance overhead when ever we add new methods to original class
• Useful for simple scenarios only
  
• Mock 
• 
  

Mockito

•  <dependency>
              <groupId>org.mockito</groupId>
              <artifactId>mockito-core</artifactId>
   </dependency>
• Key classes
  

  Mockito
  BDDMockito
  Matchers
  CoreMatchers
• Mock()
• Dynamic Stub & provides much more functionality than Stubs
  
• Stubbing a method
  
• when(mock.method("param")).thenReturn(value);
• Return multiple values with Method stubbing
• when(mock.method("param")).thenReturn(1).thenReturn(3);
• Argument Matchers
• when(mock.method(anyInt())).thenReturn(1).thenReturn(3)
• any()
• Exception
•  when(mock.method(anyInt())).thenThrow(new RuntimeException("asdf"))
•  BDD Style(Behavior Driven Development)
  
• Given-When-Then(Setup-actual method call-assert
• given(mock.method(anyInt())).willReturn(1)
• Verify Calls
• verify(mock).deleteTodo("param")
• Verify method is not called
•  verify(mock, never()).deleteTodo("param")
• #times called
•  verify(mock, times(1)).deleteTodo("param")
•  verify(mock, atLeast(1)).deleteTodo("param")
•  Capture an argument passed
• then(mock).should().deleteTodo("param")
• Declare an argument Captor
  ArugumentCaptor<String> stringArgumentCaptor = ArgumentCaptor.forClass(String.class);
  
• Declare an argument Captor on specific method call
  then(mock).should().deleteTodo(stringArgumentCaptor)
• Capture the argument
  assertThat(stringArgumentCaptor.getValue(),is("Learn to Dance"));
  assertThat(stringArgumentCaptor.getAllValues().size(),is(2));

Hamcrest

• Readable assers
• assertThat(scores, hasSize(4))
• assertThat("", isEmptyString)

Mockito Annotations

• @Mock
• Similar to Autowire annotations that creates mock for the Class type
• This requires specific kind of runner to autowire it.  -> RunWith(MockitoJUnitRunner.class)
• @InjectMocks
•  Automatically inject the dependencies that constructor dependencies
  
• @RunWith(MockitoJUnitRunner.class)
• @Captor
• Argument Captor eg: ArgumentCaptor<String> stringArgumentCaptor
  
• Creates captor of particular type

Rules

• 2 Junit runners is not possible
• Rules is alternative to multiple runners
• Rule is run before and after the test
  
• @Rule
  public MockitoRule mockitoRule MockitoJUnit.rule()
  We an remove the RunWith annotation

Spy

• It creates a new copy of the class with all functionality where one can override specific methods
• eg: List arrayListSpy = spy(ArrayList.class);
  stub(arrayListSpy.size()).toReturn(5);
• Verify that a method is called or not called
  verify(arrayListSpy).add("Dummy");

PowerMock

• Mock Limitations
• Final classes
• Static methods
• final methods
• equals & hashcode
• Mock Static methods & Constructors
• Specify runner 
• @RunWith(PowerMockRunner.class)
  @PrepareForTest(UtilityClass.class)
• Initiatlize the utilityclass that has Static method
• PowerMockito.mockStatic(UtilityClass.class)
  when (UtilityClass.staticmethod(anyInt)).thenReturn(100);
• Mock Private methods
• int i = Whitebox.invokeMethod(systemUnderTest,"private method to be invoked"); 
• Mock Constructor
• @RunWith(PowerMockRunner.class)
  @PrepareForTest(UtilityClass.class)
• PowerMockito.whenNew(ArrayList.class).withAnyArguments().thenReturn(mockList)
  int size = systemUnderTest.methodUsingAnArrayListConstructor();
  
  

• Testing a method or group of methods
• assertEquals("","");

SonarQube

• Facilitates continuous code inspection
• Components
• Webserver
• Searchserver
• Powered by elastic search
  
• Compute engine

SonarScanner

• Standalone progra that scans the code and submits report to server 
•