How to create a mocked (by jmockit) spring bean? - spring

Question

I am new to jmockit and would like to mock a bean inside my Java based Spring Application Configuration. I thought (better hoped) it would go like this:
#Configuration
public class MyApplicationConfig {
#Bean // this bean should be a mock
SomeService getSomeService() {
return new MockUp<SomeService>() {#Mock String someMethod() { return ""; }}.getMockInstance();
}
#Bean // some other bean that depends on the mocked service bean
MyApplication getMyApplication(SomeService someService) {
....
}
}
But unfortunatly this fails with "Invalid place to apply a mock-up".
I wonder if I can generate jmockit mocks inside Spring Configuration classes at all. I need the bean because it is referenced by other beans and the whole Spring Context initialization fails if I do not provide the mock as a Spring bean.
Thanks for any help.

Answer 1

Just use your regular Spring configuration. In a test class, declare the type to be mocked with #Capturing. It will mock whatever the implementation class that Spring used.
Edit: added full example code below.
import javax.inject.*;
public final class MyApplication {
private final String name;
#Inject private SomeService someService;
public MyApplication(String name) { this.name = name; }
public String doSomething() {
String something = someService.doSomething();
return name + ' ' + something;
}
}
public final class SomeService {
public String getName() { return null; }
public String doSomething() { throw new RuntimeException(); }
}
import org.springframework.context.annotation.*;
#Configuration
public class MyRealApplicationConfig {
#Bean
SomeService getSomeService() { return new SomeService(); }
#Bean
MyApplication getMyApplication(SomeService someService) {
String someName = someService.getName();
return new MyApplication(someName);
}
}
import javax.inject.*;
import org.junit.*;
import org.junit.runner.*;
import static org.junit.Assert.*;
import mockit.*;
import org.springframework.test.context.*;
import org.springframework.test.context.junit4.*;
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = MyRealApplicationConfig.class)
public final class MyApplicationSpringTest {
#Inject MyApplication myApplication;
#Mocked SomeService mockService;
#BeforeClass // runs before Spring configuration
public static void setUpMocksForSpringConfiguration() {
new MockUp<SomeService>() {
#Mock String getName() { return "one"; }
};
}
#Test
public void doSomethingUsingMockedService() {
new Expectations() {{ mockService.doSomething(); result = "two"; }};
String result = myApplication.doSomething();
assertEquals("one two", result);
}
}
import org.junit.*;
import static org.junit.Assert.*;
import mockit.*;
// A simpler version of the test; no Spring.
public final class MyApplicationTest {
#Tested MyApplication myApplication;
#Injectable String name = "one";
#Injectable SomeService mockService;
#Test
public void doSomethingUsingMockedService() {
new Expectations() {{ mockService.doSomething(); result = "two"; }};
String result = myApplication.doSomething();
assertEquals("one two", result);
}
}

Answer 2

Spring-ReInject is designed to replace beans with mocks.