Using Spring mockMvc to test optional path variables

Question

I have a method in Spring MVC with optional path variable. I am trying to test it for a scenario when optional path variable is not provided.

Snippet from Controller, resource URI to invoke-

@RequestMapping(value = "/some/uri/{foo}/{bar}", method = RequestMethod.PUT)
public <T> ResponseEntity<T> someMethod(
     @PathVariable("foo") String foo, 
     @PathVariable(value = "bar", required = false) String bar
) {
    LOGGER.info("foo: {}, bar: {}", foo, bar);
}

Snippet from my test using MockMvc-

//inject context
@Autowired
private WebApplicationContext webApplicationContext;

protected MockMvc mockMvc;

@Before
public void setup() {
    //build mockMvc
    mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
}

@Test
public void someMethodTest() throws Exception {
    //works as expected
    mockMvc.perform(put("/some/uri/{foo}/{bar}", "foo", "bar"))
            .andExpect(status().isOk()); //works

    //following doesn't work

    //pass null for optional
    mockMvc.perform(put("/some/uri/{foo}/{bar}", "foo", null))
            .andExpect(status().isOk()); //throws 404

    //pass empty for optional
    mockMvc.perform(put("/some/uri/{foo}/{bar}", "foo", ""))
            .andExpect(status().isOk()); //throws 404

    //remove optional from URI
    mockMvc.perform(put("/some/uri/{foo}", "foo"))
            .andExpect(status().isOk()); //throws 404
}

Answer 1

Using an array of @RequestMapping values like this ...

@RequestMapping(
    value = {"/some/uri/{foo}", "/some/uri/{foo}/{bar}"}, 
    method = RequestMethod.PUT)
public ResponseEntity<String> someMethod(
    @PathVariable("foo") String foo, 
    @PathVariable(value = "bar", required = false) String bar
) {
    return new ResponseEntity<>(foo + " and " + (bar == null ? "<null>" : bar), HttpStatus.OK);
}

... will enable this test to pass:

@Test
public void someMethodTest() throws Exception {
    MvcResult mvcResult = mockMvc.perform(put("/some/uri/{foo}/{bar}", "foo", "bar"))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and bar", mvcResult.getResponse().getContentAsString());

    mvcResult = mockMvc.perform(put("/some/uri/{foo}/{bar}", "foo", null))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and <null>", mvcResult.getResponse().getContentAsString());

    mvcResult = mockMvc.perform(put("/some/uri/{foo}/{bar}", "foo", ""))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and <null>", mvcResult.getResponse().getContentAsString());

    mvcResult = mockMvc.perform(put("/some/uri/{foo}", "foo"))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and <null>", mvcResult.getResponse().getContentAsString());
}

That certainly seems to be the simplest solution and it is likely to be more friendly to tools such as Swagger since it make the mappings explicit.

However, you could also declare a wildcard mapping and then use a path matcher within your controller method to interpret the request URI. For example, this method ...

private final AntPathMatcher antPathMatcher = new AntPathMatcher();

@RequestMapping(value = "/some/uri/with/wildcards/**", method = RequestMethod.PUT)
public ResponseEntity<String> someMethod(HttpServletRequest request) {
    String matched = antPathMatcher.extractPathWithinPattern(
            (String) request.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE), request.getPathInfo());
    // ugly parsing code to read the path variables, allowing for the optionality of the second one
    String foo = matched;
    String bar = null;
    String[] pathVariables = matched.split("/");
    if (pathVariables.length > 1) {
        foo = pathVariables[0];
        bar = pathVariables[1];
    }
    return new ResponseEntity<>(foo + " and " + (bar == null ? "<null>" : bar), HttpStatus.OK);
}

... will enable this test to pass:

@Test
public void someMethodTestWithWildcards() throws Exception {
    MvcResult mvcResult = mockMvc.perform(put("/some/uri/with/wildcards/{foo}/{bar}", "foo", "bar"))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and bar", mvcResult.getResponse().getContentAsString());

    mvcResult = mockMvc.perform(put("/some/uri/with/wildcards/{foo}/{bar}", "foo", null))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and <null>", mvcResult.getResponse().getContentAsString());

    mvcResult = mockMvc.perform(put("/some/uri/with/wildcards/{foo}/{bar}", "foo", ""))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and <null>", mvcResult.getResponse().getContentAsString());

    mvcResult = mockMvc.perform(put("/some/uri/with/wildcards/{foo}", "foo"))
            .andExpect(status().isOk()).andReturn();
    Assert.assertEquals("foo and <null>", mvcResult.getResponse().getContentAsString());
}