Spring MVC test post method with controller redirect

Question

I have a test:

@Test
public void shouldAddCompany() throws Exception {
    mockMvc.perform(post("/companies")
            .param("name", "companyName"))
            .andExpect(model().attribute("company",
                    hasProperty("name", is("companyName"))));

}

and my controller method looks like that:

@PostMapping("/companies")
public String displayCompaniesPost(@ModelAttribute Company company) {
    companyService.save(company);
    return "redirect:/companies";
}

How can i check company attribute in test? There is a problem because of redirect and status 302.

 java.lang.AssertionError: Model attribute 'company'
 Expected: hasProperty("name", is "companyName")
 but: was null

I think it occurs because controller is going to GET method because of redirection. When I remove this redirection everything is ok, but I don't want to remove that redirection.

EDIT (GetMapping):

@GetMapping({"/", "/companies"})
public String displayCompanies(Model model) {
    model.addAttribute("company", new Company());
    List<Company> companies = companyService.findAll();
    model.addAttribute("companies", companies);
    return "companies";
}

I thought the problem is because of addding attribute with the same name in getMapping, but when I removed it, it still doesn't work.

Answer 1

You need to modify your approach. If you POST to a controller method, and it returns a Redirect you will have no ability to access any model information set by that controller, it just returns an HTTP 302 with a Location Header to the client telling it the new url to go to (in this case GET /companies). If this is a strictly Unit test, that is the extent of what you can test for this method.

I would consider instead treating this as an integration test, and change your test to have two separate steps:

1. POST /companies and validate that the response is the expected redirect
2. GET /companies and validate that the list of companies returned contains the new company you posted in step 1