Unit testing with Spring Security

Question

My company has been evaluating Spring MVC to determine if we should use it in one of our next projects. So far I love what I've seen, and right now I'm taking a look at the Spring Security module to determine if it's something we can/should use.

Our security requirements are pretty basic; a user just needs to be able to provide a username and password to be able to access certain parts of the site (such as to get info about their account); and there are a handful of pages on the site (FAQs, Support, etc) where an anonymous user should be given access.

In the prototype I've been creating, I have been storing a "LoginCredentials" object (which just contains username and password) in Session for an authenticated user; some of the controllers check to see if this object is in session to get a reference to the logged-in username, for example. I'm looking to replace this home-grown logic with Spring Security instead, which would have the nice benefit of removing any sort of "how do we track logged in users?" and "how do we authenticate users?" from my controller/business code.

It seems like Spring Security provides a (per-thread) "context" object to be able to access the username/principal info from anywhere in your app...

Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();

... which seems very un-Spring like as this object is a (global) singleton, in a way.

My question is this: if this is the standard way to access information about the authenticated user in Spring Security, what is the accepted way to inject an Authentication object into the SecurityContext so that it is available for my unit tests when the unit tests require an authenticated user?

Do I need to wire this up in the initialization method of each test case?

protected void setUp() throws Exception {
    ...
    SecurityContextHolder.getContext().setAuthentication(
        new UsernamePasswordAuthenticationToken(testUser.getLogin(), testUser.getPassword()));
    ...
}

This seems overly verbose. Is there an easier way?

The SecurityContextHolder object itself seems very un-Spring-like...

Answer 1

After quite a lot of work I was able to reproduce the desired behavior. I had emulated the login through MockMvc. It is too heavy for most unit tests but helpful for integration tests.

Of course I am willing to see those new features in Spring Security 4.0 that will make our testing easier.

package [myPackage]

import static org.junit.Assert.*;

import javax.inject.Inject;
import javax.servlet.http.HttpSession;

import org.junit.Before;
import org.junit.Test;
import org.junit.experimental.runners.Enclosed;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mock.web.MockHttpServletRequest;
import org.springframework.security.core.context.SecurityContext;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.FilterChainProxy;
import org.springframework.security.web.context.HttpSessionSecurityContextRepository;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;

@ContextConfiguration(locations={[my config file locations]})
@WebAppConfiguration
@RunWith(SpringJUnit4ClassRunner.class)
public static class getUserConfigurationTester{

    private MockMvc mockMvc;

    @Autowired
    private FilterChainProxy springSecurityFilterChain;

    @Autowired
    private MockHttpServletRequest request;

    @Autowired
    private WebApplicationContext webappContext;

    @Before  
    public void init() {  
        mockMvc = MockMvcBuilders.webAppContextSetup(webappContext)
                    .addFilters(springSecurityFilterChain)
                    .build();
    }  


    @Test
    public void testTwoReads() throws Exception{                        

    HttpSession session  = mockMvc.perform(post("/j_spring_security_check")
                        .param("j_username", "admin_001")
                        .param("j_password", "secret007"))
                        .andDo(print())
                        .andExpect(status().isMovedTemporarily())
                        .andExpect(redirectedUrl("/index"))
                        .andReturn()
                        .getRequest()
                        .getSession();

    request.setSession(session);

    SecurityContext securityContext = (SecurityContext)   session.getAttribute(HttpSessionSecurityContextRepository.SPRING_SECURITY_CONTEXT_KEY);

    SecurityContextHolder.setContext(securityContext);

        // Your test goes here. User is logged with 
}

Answer 2

Without answering the question about how to create and inject Authentication objects, Spring Security 4.0 provides some welcome alternatives when it comes to testing. The @WithMockUser annotation enables the developer to specify a mock user (with optional authorities, username, password and roles) in a neat way:

@Test
@WithMockUser(username = "admin", authorities = { "ADMIN", "USER" })
public void getMessageWithMockUserCustomAuthorities() {
    String message = messageService.getMessage();
    ...
}

There is also the option to use @WithUserDetails to emulate a UserDetails returned from the UserDetailsService, e.g.

@Test
@WithUserDetails("customUsername")
public void getMessageWithUserDetailsCustomUsername() {
    String message = messageService.getMessage();
    ...
}

More details can be found in the @WithMockUser and the @WithUserDetails chapters in the Spring Security reference docs (from which the above examples where copied)

Answer 3

The problem is that Spring Security does not make the Authentication object available as a bean in the container, so there is no way to easily inject or autowire it out of the box.

Before we started to use Spring Security, we would create a session-scoped bean in the container to store the Principal, inject this into an "AuthenticationService" (singleton) and then inject this bean into other services that needed knowledge of the current Principal.

If you are implementing your own authentication service, you could basically do the same thing: create a session-scoped bean with a "principal" property, inject this into your authentication service, have the auth service set the property on successful auth, and then make the auth service available to other beans as you need it.

I wouldn't feel too bad about using SecurityContextHolder. though. I know that it's a static / Singleton and that Spring discourages using such things but their implementation takes care to behave appropriately depending on the environment: session-scoped in a Servlet container, thread-scoped in a JUnit test, etc. The real limiting factor of a Singleton is when it provides an implementation that is inflexible to different environments.

Answer 4

I would take a look at Spring's abstract test classes and mock objects which are talked about here. They provide a powerful way of auto-wiring your Spring managed objects making unit and integration testing easier.

Answer 5

Personally I would just use Powermock along with Mockito or Easymock to mock the static SecurityContextHolder.getSecurityContext() in your unit/integration test e.g.

@RunWith(PowerMockRunner.class)
@PrepareForTest(SecurityContextHolder.class)
public class YourTestCase {

    @Mock SecurityContext mockSecurityContext;

    @Test
    public void testMethodThatCallsStaticMethod() {
        // Set mock behaviour/expectations on the mockSecurityContext
        when(mockSecurityContext.getAuthentication()).thenReturn(...)
        ...
        // Tell mockito to use Powermock to mock the SecurityContextHolder
        PowerMockito.mockStatic(SecurityContextHolder.class);

        // use Mockito to set up your expectation on SecurityContextHolder.getSecurityContext()
        Mockito.when(SecurityContextHolder.getSecurityContext()).thenReturn(mockSecurityContext);
        ...
    }
}

Admittedly there is quite a bit of boiler plate code here i.e. mock an Authentication object, mock a SecurityContext to return the Authentication and finally mock the SecurityContextHolder to get the SecurityContext, however its very flexible and allows you to unit test for scenarios like null Authentication objects etc. without having to change your (non test) code

Answer 6

Using a static in this case is the best way to write secure code.

Yes, statics are generally bad - generally, but in this case, the static is what you want. Since the security context associates a Principal with the currently running thread, the most secure code would access the static from the thread as directly as possible. Hiding the access behind a wrapper class that is injected provides an attacker with more points to attack. They wouldn't need access to the code (which they would have a hard time changing if the jar was signed), they just need a way to override the configuration, which can be done at runtime or slipping some XML onto the classpath. Even using annotation injection would be overridable with external XML. Such XML could inject the running system with a rogue principal.