Mocking a Keycloak token for testing a Spring controller

I want to write unit tests for my spring controller. I'm using keycloak's openid flow to secure my endpoints.

In my tests I'm using the @WithMockUser annotation to mock an authenticated user. My problem is that I'm reading the userId from the token of the principal. My unit test now fails because the userId I read from the token is null;

if (principal instanceof KeycloakAuthenticationToken) {
    KeycloakAuthenticationToken authenticationToken = (KeycloakAuthenticationToken) principal;
    SimpleKeycloakAccount account = (SimpleKeycloakAccount) authenticationToken.getDetails();
    RefreshableKeycloakSecurityContext keycloakSecurityContext = account.getKeycloakSecurityContext();
    AccessToken token = keycloakSecurityContext.getToken();
    Map<String, Object> otherClaims = token.getOtherClaims();
    userId = otherClaims.get("userId").toString();
}           

Is there anything to easily mock the KeycloakAuthenticationToken?

@WithmockUser configures the security-context with a UsernamePasswordAuthenticationToken. This can be just fine for most use-cases but when your app relies on another Authentication implementation (like your code does), you have to build or mock an instance of the right type and put it in the test security-context: SecurityContextHolder.getContext().setAuthentication(authentication);

Of course, you'll soon want to automate this, building your own annotation or RequestPostProcessor

... or ...

take one "off the shelf", like in this lib of mine, which is available from maven-central:

<dependency>
    <!-- just enough for @WithMockKeycloackAuth -->
    <groupId>com.c4-soft.springaddons</groupId>
    <artifactId>spring-security-oauth2-test-addons</artifactId>
    <version>3.0.1</version>
    <scope>test</scope>
</dependency>
<dependency>
    <!-- required only for WebMvc "fluent" API -->
    <groupId>com.c4-soft.springaddons</groupId>
    <artifactId>spring-security-oauth2-test-webmvc-addons</artifactId>
    <version>3.0.1</version>
    <scope>test</scope>
</dependency>

You can use it either with @WithMockKeycloackAuth annotations:

@RunWith(SpringRunner.class)
@WebMvcTest(GreetingController.class)
@ContextConfiguration(classes = GreetingApp.class)
@ComponentScan(basePackageClasses = { KeycloakSecurityComponents.class, KeycloakSpringBootConfigResolver.class })
public class GreetingControllerTests extends ServletUnitTestingSupport {
    @MockBean
    MessageService messageService;

    @Test
    @WithMockKeycloackAuth("TESTER")
    public void whenUserIsNotGrantedWithAuthorizedPersonelThenSecretRouteIsNotAccessible() throws Exception {
        mockMvc().get("/secured-route").andExpect(status().isForbidden());
    }

    @Test
    @WithMockKeycloackAuth("AUTHORIZED_PERSONNEL")
    public void whenUserIsGrantedWithAuthorizedPersonelThenSecretRouteIsAccessible() throws Exception {
        mockMvc().get("/secured-route").andExpect(content().string(is("secret route")));
    }

    @Test
    @WithMockKeycloakAuth(
            authorities = { "USER", "AUTHORIZED_PERSONNEL" },
            claims = @OpenIdClaims(
                    sub = "42",
                    email = "ch4mp@c4-soft.com",
                    emailVerified = true,
                    nickName = "Tonton-Pirate",
                    preferredUsername = "ch4mpy",
                    otherClaims = @Claims(stringClaims = @StringClaim(name = "foo", value = "bar"))))
    public void whenAuthenticatedWithKeycloakAuthenticationTokenThenCanGreet() throws Exception {
        mockMvc().get("/greet")
                .andExpect(status().isOk())
                .andExpect(content().string(startsWith("Hello ch4mpy! You are granted with ")))
                .andExpect(content().string(containsString("AUTHORIZED_PERSONNEL")))
                .andExpect(content().string(containsString("USER")));
    }

Or MockMvc fluent API (RequestPostProcessor):

@RunWith(SpringRunner.class)
@WebMvcTest(GreetingController.class)
@ContextConfiguration(classes = GreetingApp.class)
@ComponentScan(basePackageClasses = { KeycloakSecurityComponents.class, KeycloakSpringBootConfigResolver.class })
public class GreetingControllerTest extends ServletKeycloakAuthUnitTestingSupport {
    @MockBean
    MessageService messageService;

    @Test
    public void whenUserIsNotGrantedWithAuthorizedPersonelThenSecretMethodIsNotAccessible() throws Exception {
        mockMvc().with(authentication().roles("TESTER")).get("/secured-method").andExpect(status().isForbidden());
    }

    @Test
    public void whenUserIsGrantedWithAuthorizedPersonelThenSecretMethodIsAccessible() throws Exception {
        mockMvc().with(authentication().roles("AUTHORIZED_PERSONNEL")).get("/secured-method")
                .andExpect(content().string(is("secret method")));
    }

}