JUnit for both try and catch block coverage

Question

I am trying to write a JUnit for below code but I am not getting any idea how to cover the code which is written in catch block statement. Please can any one write a sample JUni

Answer 1

You can mock both productCacheDao and productDao and check how many times those methods were invoked in your test cases. And you can simulate exception throwing with those mock objects, like this:

when(mockObject.method(any())).thenThrow(new IllegalStateException());

So, for your case I would do something like this:

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import static org.mockito.Mockito.*;

public class ProductTest {
    private static final Product CACHED_PRODUCT = new Product("some parameters for cached product");
    private static final Product DB_PRODUCT = new Product("some parameters for DB product");

    private ProductService service;
    private ProductDao productDaoMock;
    private ProductCacheDao productCacheDaoMock;

    @Before
    public void setup() {
        service = new ProductService();
        productDaoMock = mock(ProdoctDao.class);
        service.setProductDao(productDaoMock);

        productCacheDaoMock = mock(ProdoctCacheDao.class);
        service.setProductCacheDao(productCacheDaoMock);
    }

    @Test
    public void testCache() {
        when(productCacheDaoMock.getProductLookUpData(any())).thenReturn(CACHED_PRODUCT);

        final Product product = service.getProductLookUpData();

        Assert.assertEquals(CACHED_PRODUCT, product);
        verify(productCacheDaoMock, times(1)).getProductLookUpData(any());
        verify(productDaoMock, never()).getIpacMetricCodeLookUpData(any());
    }

    @Test
    public void testDB() {
        when(productCacheDaoMock.getProductLookUpData(any())).thenThrow(new IllegalStateException());
        when(productDaoMock.getIpacMetricCodeLookUpData(any())).thenReturn(DB_PRODUCT);

        final Product product = service.getProductLookUpData();

        Assert.assertEquals(DB_PRODUCT, product);
        verify(productCacheDaoMock, times(1)).getProductLookUpData(any());
        verify(productDaoMock, times(1)).getIpacMetricCodeLookUpData(any());
    }
}

Answer 2

Mockito, or another mocking framework can be used. You will need two test cases - with and without the exception being thrown. You can mock your DAOs to return a known object so you verify your service is exhibiting the correct behaviour.

I've written a full example below.

public class MocksExample {

    private ProductService service;
    @Mock
    private ProductDao productDao;
    @Mock
    private ProductCacheDao productCacheDao;
    @Mock
    private Product product;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
        service = new ProductService();
        service.setProductCacheDao(productCacheDao);
        service.setProductDao(productDao);
    }

    @Test
    public void serviceReturnsProduct() {
        when(productCacheDao.getProductLookUpData()).thenReturn(product);
        assertThat(service.getProductLookUpData(), is(product));
    }

    @Test
    public void ipacProductReturnedWhenDaoThrowsException() {
        when(productDao.getIpacMetricCodeLookUpData()).thenReturn(product);
        when(productCacheDao.getProductLookUpData()).thenThrow(new IllegalStateException("foo"));
        assertThat(service.getProductLookUpData(), is(product));
    }
}

Answer 3

You can use Mocking frameworks like Mockito

In your JUnit Test you can do something like

public class YourTest {

  private ProductcacheDao productCacheDaoMock;

  @Before
  public void setup() throws Exception {

    productCacheDaoMock = Mockito.mock(ProductcacheDao.class);

  }

  @org.junit.Test
  public void test() {
      // Given
      Mockito.when(productCacheDaoMock.getProductLookUpData()).thenThrow(new RuntimeException());

      // When
      // do your stuff
      productCacheDaoMock.getProductLookUpData();

      // Then
      // ...
  }

}