How to mock an objects method call thats within a method?

Question

So here is the class and method I want to create a test for:

public class RequestController {    
private GetAllInter getAnalytics;//This is an interface

@RequestMapping(value ="",method=RequestMethod.GET)
public String getAllAnalytics(){
    log.debug("Processing request for all analytics");
    String result;
    try {
        result = getAnalytics.getAll();
    } catch (Exception e) {
        result = "Could not retrieve full list of analytics";
        log.error(result,e);
    }
    return result;
}

Specifically I want mock the getAnalytics.getAll() so it returns a String I already defined. Instead of the method doing its thing. This is my code:

public class RequestControllerTest extends Mockito{

private String allAnalyticsStr = "Hello";

@Test
public void testGetAllAnalytics(){
    GetAllInter getAll = mock(GetAllInter.class);
    when(getAll.getAll()).thenReturn("what");
    RequestController requestController = new RequestController();
    assert(requestController.getAllAnalytics().equals("Hello"));
}

And when I try to run the test this is the error im getting:

16:17:03.240 [main] DEBUG dar.RequestController - Processing requst for all analytics 16:17:03.248 [main] ERROR dar.RequestController - Could not retrieve full list of analytics java.lang.NullPointerException: null at dar.RequestController.getAllAnalytics(RequestController.java:32) ~[classes/:na] at dar.RequestControllerTest.testGetAllAnalytics(RequestControllerTest.java:28) [test-classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_79] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_79] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_79] at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_79] at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) [junit-4.12.jar:4.12] at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12] at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) [junit-4.12.jar:4.12] at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) [junit-4.12.jar:4.12] at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) [junit-4.12.jar:4.12] at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) [junit-4.12.jar:4.12] at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12] at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12] at org.junit.runner.JUnitCore.run(JUnitCore.java:137) [junit-4.12.jar:4.12] at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117) [junit-rt.jar:na] at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) [junit-rt.jar:na] at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) [junit-rt.jar:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_79] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_79] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_79] at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_79] at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na] and

java.lang.AssertionError at dar.RequestControllerTest.testGetAllAnalytics(RequestControllerTest.java:28) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) Any idea what I'm doing wrong? Is there another way to do this? Is it because I am mocking an interface of the class and not the class itself?

Satoshi Satoshi · Accepted Answer · 2016-02-25T21:34:49

You need to replace RequestController#getAnalytics field with mocked GetAllInter instance before executing test.

GetAllInter getAll = mock(GetAllInter.class);
when(getAll.getAll()).thenReturn("what");

That statement doesn't effect RequestController's getAnalytics instance behavior until you set it as RequestController's field.

I found similar question mockito - mocking an interface - throwing NullPointerException

The easiest way is provide setter for RequestController#getAllanalytics or provide RequestController constructor taking GetAllInter argument.

But using @InjectMocks would be nicer solution since you don't need to modify the RequestController class for testing.

How to mock an objects method call thats within a method?

1 Answers