MockMvc tests that use `contextPath` fail with Thymeleaf 3.1

While preparing an application to use the upcoming Spring Boot v3 a lot of tests fail where MockMvc is used. The application is configured with a server.servlet.context-path which is also used in the tests. For Spring Boot v2 these tests are successfully running. The minimal test is:

@SpringBootTest
@AutoConfigureMockMvc
class DemoApplicationTests {

    @Autowired
    private MockMvc mockMvc;

    @Value("${server.servlet.context-path}")
    private String contextPath;

    @Test
    public void shouldServeIndex_mockMvc() throws Exception {
        mockMvc.perform(MockMvcRequestBuilders.get(contextPath + "/").contextPath(contextPath))
                .andExpect(status().isOk());
    }

    @Test
    public void shouldServeIndex_webClient() throws Exception {
        try (final var webClient = MockMvcWebClientBuilder.mockMvcSetup(mockMvc).contextPath(contextPath).build()) {
            webClient.getPage("http://localhost" + contextPath + "/");
        }
    }

}

Running with Spring Boot 3.0.0-RC2 both tests fail with:

[ERROR] shouldServeIndex_mockMvc  Time elapsed: 0.236 s  <<< ERROR!
jakarta.servlet.ServletException: Request processing failed: java.lang.IllegalArgumentException: Cannot build an application for a request which servlet context does not match with the application that it is being built for.
        at com.example.demo.DemoApplicationTests.shouldServeIndex_mockMvc(DemoApplicationTests.java:26)
Caused by: java.lang.IllegalArgumentException: Cannot build an application for a request which servlet context does not match with the application that it is being built for.
        at com.example.demo.DemoApplicationTests.shouldServeIndex_mockMvc(DemoApplicationTests.java:26)

The check in org.thymeleaf.web.servlet.JakartaServletWebApplication#servletContextMatches fails because the provided current context path is not equal (it’s empty) to the requested one. The module for Spring (Framework) 5 does not check the context paths.

A test project can be found here.

[agebhar1]

@philwebb thank you for discussing this issue. It will work for me to remove the context path from the Tomcat configuration and add them to all controller. I’d like the test URLs to be equal to the productive ones. Maybe a hint should be added to the documentation to be aware of the situation.

[philwebb]

I’m a little worried that if we try and set the context path in the tests then it might break a lot of users in the other direction.

The javadoc for MockHttpServletRequestBuilder.contextPath(...) states:

In most cases, tests can be written by omitting the context path from the requestURI. This is because most applications don’t actually depend on the name under which they’re deployed. If specified here, the context path must start with a “/” and must not end with a “/”.

If we set the context path on our mock servlet then all mock MVC calls will need to remember to also set it.

If I drop it entirely from the tests, things work:

@SpringBootTest
@AutoConfigureMockMvc
class DemoApplicationTests {

	@Autowired
	private MockMvc mockMvc;

	@Test
	public void shouldServeIndex_mockMvc() throws Exception {
		mockMvc.perform(MockMvcRequestBuilders.get("/")).andExpect(status().isOk());
	}

	@Test
	public void shouldServeIndex_webClient() throws Exception {
		try (final var webClient = MockMvcWebClientBuilder.mockMvcSetup(mockMvc).build()) {
			webClient.getPage("http://localhost/");
		}
	}

}