Learn to write unit test which invokes a method multiple times with different arguments – and then verifies the method invocations and method arguments separately.
1. Verify multiple method calls with different arguments
The given unit test has mocked the HashMap class and invokes in put(key, value) code twice. It then verifies that method had been invoked twice. The test further verifies all the different method arguments separately.
import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.times;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.ArgumentCaptor;
import org.mockito.Captor;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.junit.MockitoJUnitRunner;
@RunWith(MockitoJUnitRunner.class)
public class MockitoExample
{
@Mock
HashMap<String, Integer> hashMap;
@Captor
ArgumentCaptor<String> keyCaptor;
@Captor
ArgumentCaptor<Integer> valueCaptor;
@Test
public void saveTest()
{
hashMap.put("A", 10);
hashMap.put("B", 20);
//1. Verify method was invoked N times
Mockito.verify(hashMap, times(2)).put(keyCaptor.capture(), valueCaptor.capture());
List<String> keys = keyCaptor.getAllValues();
List<Integer> values = valueCaptor.getAllValues();
//2. Verify method argument values as list
assertEquals(Arrays.asList("A", "B"), keys);
assertEquals(Arrays.asList(Integer.valueOf(10), Integer.valueOf(20)), values);
//3. Verify method arguments separately
assertEquals("A", keys.get(0));
assertEquals("B", keys.get(1));
assertEquals(Integer.valueOf(10), values.get(0));
assertEquals(Integer.valueOf(20), values.get(1));
}
}
2. Explanation
To capture and verify all the method arguments passed to a method when it is invoked multiple times, we shall follow below steps:
- Use
Mockito.verify(mock, times(n))to verify if method was executed'n'times. - Create as many
ArgumentCaptorinstances as the number of arguments in the method. In above example, we tested the HashMap which work on key-value pairs, so we created twoArgumentCaptorinstances – one for key and second for value. - Use
ArgumentCaptor.getAllValues()to retrieve all the values passed to one method parameter during all executions. It returns aListof passed argument values. - We can use
assertEquals(expected, result)to verify that expected multiple arguments match with the retrieved values fromArgumentCaptor.
Drop me your questions related to invoking a method multiple times and verify it’s method different arguments values in mockito based unit tests.
Happy Learning !!
Supriya Chougule
hi. I am writing a test case for a class which like this:
public class A {
public void methodOne(int argument) {
//some operations
methodTwo(argument);
//some operations
}
private void methodTwo(int argument) {
ReportClass report = new ReportClass ();
//use dateTime to perform some operations
}
}
in this case i am not allowed to perform any change in src code but I need to set some attributes to ReportClass. beacuse of this class test case getting failed. I don’t know how to write a test case for this class.
Wayne
I want one method to return different result after some time eg. 1s. This is for rate limit test. How to mock it?
Bart
Hi Lokesh,
I have a class which must be tested with Mockito. De class has two dependent worker classes. Both worker classes are mocked in the test. But each of the two worker classes has the same argument type. How can I capture the two invocations of the two worker classes and check if the worker classes are called with the proper arguments ?
Kind regards,
Bart
Sydney
Hi Lokesh,
I want to put some static values in either array or hash map and compare them with logs in a CSV document to verify whether those values are being passed. what is the best of doing it
For ex: CSV contains a value like in JSON request and I want to make sure this value is passed whenever the app is run