Unit Test Notes
Tags (space delimited): TestNg mockito
Learning Links
Mockito Official Documentation
Geek College
TestNg
Mockito Chinese Tutorial
Mockito usage scenarios
We often encounter classes that have a lot of dependencies to test, and these dependent classes/objects/resources have other dependencies, thus forming a large dependency tree. It is difficult to build such dependencies completely in the environment of unit testing.
Basic Use
@Test
public void test() {
ObjectB objectB = mock(ObjectB.class);
ObjectA objectA = new ObjectA();
objectA.setPwString("testString");
when(objectB.getObjectA()).thenReturn(objectA);
ObjectA actucalA = objectB.getObjectA();
assertEquals(objectA, actucalA);
}Note that MockitoAnnotations.initMocks(this) is required when using annotation fast Mocks; Reference 2.5
Parameter Matching
You can write exact values or use any() when matching method parameters
when(templateDAO.findAll(any(TemplateSpecification.class))).thenThrow(new
DataAccessException("query template failed") {
private static final long serialVersionUID = -6784264998739312988L;
});
when(templateDAO.findAll(any(TemplateSpecification.class))).thenThrow(new
DataAccessException("query template failed") {
}); - Note here that once a matcher is used for a parameter, the subsequent parameters must match
- You can customize parameter matching yourself
The difference between doReturn().when() and when().doReturn()
Here you need to note the difference between when().doReturn and doReturn().when().
- doReturn().when() does not really call the method
- when().doReturn() does not call a method when the monitoring object is a full mock object (because the mock is a dummy object), but it does call the method when the object is spy
- When the return value of the calling method is empty, only doReturn().when().method() can be used.
Validation Exception
Code Validation
@Rule
public ExpectedException expectedEx = ExpectedException.none();
//...
expectedEx.expect(CannotUploadTemplateException.class);
expectedEx.expectMessage("Template Rejected");
expectedEx.expect(CannotUploadTemplateException.class);
expectedEx.expectMessage("Template Rejected"); Use comments to validate exceptions
@Test(expected = RuntimeException.class)
public void doThrow_when(){
List list = mock(List.class);
doThrow(new RuntimeException()).when(list).add(1);
list.add(1);
}
Spy Detection Object
spy is a technology that can detect real objects, can monitor methods and set object behavior, so we need to pay attention to the difference between doReturn().when() and when().doReturn(), which is a kind of half-mock object that can be understood as a real and virtual object.
@Test
public void test() {
ObjectB objectB = spy(new ObjectB());
ObjectA objectA = new ObjectA();
objectA.setPwString("testString");
when(objectB.getObjectA()).thenReturn(objectA);
ObjectA actucalA = objectB.getObjectA();
assertEquals(objectA, actucalA);
//Here getValue() calls the actual method and the return value is "hello world"
assertEquals("hello world", objectB.getValue());
}
Reset Mock
@Test
public void reset_mock(){
List list = mock(List.class);
when(list.size()).thenReturn(10);
list.add(1);
assertEquals(10,list.size());
//Reset mock, clear all interactions and presets
reset(list);
assertEquals(0,list.size());
}Continuous calls
@Test(expected = RuntimeException.class)
public void consecutive_calls(){
//Simulate continuous calls to return expected values, if separate, only the last valid
when(mockList.get(0)).thenReturn(0);
when(mockList.get(0)).thenReturn(1);
when(mockList.get(0)).thenReturn(2);
when(mockList.get(1)).thenReturn(0).thenReturn(1).thenThrow(new RuntimeException());
assertEquals(2,mockList.get(0));
assertEquals(2,mockList.get(0));
assertEquals(0,mockList.get(1));
assertEquals(1,mockList.get(1));
//The third or more calls throw an exception
mockList.get(1);
}