Mocking @AuthenticationPrincipal for a unit test

Question

I am new to spring and lombok. I am working on a unit test for a controller where the method uses @AuthenticationPrincipal. From what I have read it passes the information of the authenticated user into the method. Is there a way to mock this for the unit test?

Answer 1

The easiest solution that comes to mind is @WithMockUser. It does what you asked for. But, in case you are not satisfied with it, you can create an annotation and tune it to your needs.

I am assuming that you have tried @WithMockUser and it really didn't fit your needs.

There are three important tasks. The first is creating an annotation followed by creating a class that represents a user of your system and finally creating SecurityContextFactory.

1. Let's start with the annotation

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

import org.springframework.security.test.context.support.WithSecurityContext;

@Retention(RetentionPolicy.RUNTIME)
@WithSecurityContext(factory = WithMockAaronSecurityContextFactory.class)
public @interface WithAaronUser {
    String username() default "TestUser";
    String[] roles() default { "ROLE_ADMIN" };
}

2. A mock user class

import java.util.Collection;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;

public class MockUserDetails {

    private String username;
    private Collection<? extends GrantedAuthority> authorities;
    
    public MockUserDetails(String username, String[] roles) {
        this.username = username;
        this.authorities = Stream.of(roles)
                .map(role -> new SimpleGrantedAuthority(role)).collect(Collectors.toSet());
    }

    public String getUsername() {
        return username;
    }

    public Collection<? extends GrantedAuthority> getAuthorities() {
        return authorities;
    }
}

3 Finally the SecurityContextFactory. Note that the implementation uses the same factory class (WithSecurityContextFactory) that @WithMockUser uses.

import java.io.Serializable;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.springframework.mock.web.MockHttpServletRequest;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.AuthorityUtils;
import org.springframework.security.core.context.SecurityContext;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.oauth2.provider.OAuth2Authentication;
import org.springframework.security.oauth2.provider.OAuth2Request;
import org.springframework.security.oauth2.provider.authentication.OAuth2AuthenticationDetails;
import org.springframework.security.test.context.support.WithSecurityContextFactory;

public class WithMockAaronSecurityContextFactory implements WithSecurityContextFactory<WithAaronUser> {

    @Override
    public SecurityContext createSecurityContext(WithAaronUser user) {

        MockUserDetails principal = new MockUserDetails(user.username(), user.roles());

        MockHttpServletRequest request = new MockHttpServletRequest();
        request.setServerName("www.example.com");
        request.setRequestURI("/token");
        request.setQueryString("param1=value1&param");
        request.setAttribute(OAuth2AuthenticationDetails.ACCESS_TOKEN_VALUE, "mocked_token");
        OAuth2AuthenticationDetails authDetails = new OAuth2AuthenticationDetails(request);
        
        Map<String, String> decodedDetails = new HashMap<>();
        decodedDetails.put("first_name", "Jean-Claude");
        decodedDetails.put("last_name", "Van Damme");
        authDetails.setDecodedDetails(decodedDetails);
        
        
        UsernamePasswordAuthenticationToken auth = new UsernamePasswordAuthenticationToken(principal.getUsername(), "password", principal.getAuthorities());
        auth.setDetails(authDetails);
        
        
        List<GrantedAuthority> authorities = AuthorityUtils.createAuthorityList("ROLE_ADMIN");
        OAuth2Request oAuth2Request = new OAuth2Request(Collections.emptyMap(), "", authorities, true, Collections.emptySet(), Collections.emptySet(), "http://somethig.com", Collections.emptySet(), Collections.emptyMap());
                    
                    
        OAuth2Authentication oAuth = new OAuth2Authentication(getOauth2Request(), auth);
        oAuth.setDetails(authDetails);
            
        SecurityContext context = SecurityContextHolder.createEmptyContext();
        context.setAuthentication(oAuth);
        return context;
    }
}