Mocking FacesContext

Question

I am trying to add some unit tests to a JSF application. This application didnt rely heavily on any best practices, so many service methods use the FacesContext to

Answer 1

This url provides a really good article on it: http://illegalargumentexception.blogspot.com/2011/12/jsf-mocking-facescontext-for-unit-tests.html

You have your managed bean:

 package foo;

import java.util.Map;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.faces.context.FacesContext;

@ManagedBean
@RequestScoped
public class AlphaBean {
  public String incrementFoo() {
    Map session = FacesContext.getCurrentInstance()
        .getExternalContext()
        .getSessionMap();
    Integer foo = (Integer) session.get("foo");
    foo = (foo == null) ? 1 : foo + 1;
    session.put("foo", foo);
    return null;
  }
}

You stub out the FacesContext:

package foo.test;

import javax.faces.context.FacesContext;

import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;

public abstract class ContextMocker extends FacesContext {
  private ContextMocker() {
  }

  private static final Release RELEASE = new Release();

  private static class Release implements Answer {
    @Override
    public Void answer(InvocationOnMock invocation) throws Throwable {
      setCurrentInstance(null);
      return null;
    }
  }

  public static FacesContext mockFacesContext() {
    FacesContext context = Mockito.mock(FacesContext.class);
    setCurrentInstance(context);
    Mockito.doAnswer(RELEASE)
        .when(context)
        .release();
    return context;
  }
}

Then write your unit test:

@Test
  public void testIncrementFoo() {
    FacesContext context = ContextMocker.mockFacesContext();
    try {
      Map session = new HashMap();
      ExternalContext ext = mock(ExternalContext.class);
      when(ext.getSessionMap()).thenReturn(session);
      when(context.getExternalContext()).thenReturn(ext);

      AlphaBean bean = new AlphaBean();
      bean.incrementFoo();
      assertEquals(1, session.get("foo"));
      bean.incrementFoo();
      assertEquals(2, session.get("foo"));
    } finally {
      context.release();
    }
  }