How to mock HttpServletRequest and HttpServletResponse objects?

Question

I have a simple servlet. He forward to jsp page. But when I use mock objects for HttpServletRequest and HttpServletResponse instead original objects in my test, I get NullPointerException.

public class SimpleServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.getRequestDispatcher("WEB-INF/views/AdminMenu.jsp")
                .forward(req, resp); // In this place I get NPE (16th string.)
    }
}

This is my test which create HttpServletRequest and HttpServletResponseobjects and send their into doPost method:

@Test
public void test() throws ServletException, IOException {

    final HttpServletRequest req = mock(HttpServletRequest.class);
    final HttpServletResponse resp = mock(HttpServletResponse.class);


    final SimpleServlet simpleServlet = new SimpleServlet();

    simpleServlet.doPost(req, resp);

}

This is my log after running text:

java.lang.NullPointerException
    at ru.pravvich.servlets.SimpleServlet.doPost(SimpleServlet.java:16)
    at ru.pravvich.servlets.SimpleServletTest.test(SimpleServletTest.java:28)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    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.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.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

What reason? Help me fix this issue. Thank You.

since you mocked the request, you need to provide getRequestDispatcher(). By default its returning NULL. — Minh Kieu
– Minh Kieu, Commented Jun 20, 2017 at 12:01
per default mocks return null unless you configured a return value. This means you need to configure the HttpServletRequestmock to return something when method getRequestDispatcher() is called on it. — Timothy Truckle
– Timothy Truckle, Commented Jun 20, 2017 at 12:01

kk. · Accepted Answer · 2017-06-20 12:07:46Z

3

Mock the call of req.getRequestDispatcher("WEB-INF/views/AdminMenu.jsp") to avoid NullPointerException.

answered Jun 20, 2017 at 12:07

kk.

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want2learn · Accepted Answer · 2017-06-20 16:27:16Z

2

You need to add following

RequestDispatcher rd = mock(RequestDispatcher.class);
when(req.getRequestDispatcher(eq("WEB-INF/views/AdminMenu.jsp"))).thenReturn(rd);

answered Jun 20, 2017 at 16:27

want2learn

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