Improper UTF-8 handling in MockMvc for JSON response

[sgybas]

When MediaType.APPLICATION_JSON_UTF8 was deprecated, the content type of JSON that gets sent from a @RestController changed to application/json (without charset).

This breaks MockMvc tests that use .andExpect(content().json()). Here is a sample test:

@Test
public void returnsTheExpectedResponse() throws Exception {
    mockMvc.perform(get("/"))
        .andExpect(status().isOk())
        .andExpect(content().json("{\"name\":\"Jürgen\"}"));
}

The test runs fine with Spring 5.1.9 but fails with Spring 5.2.0.RC2

java.lang.AssertionError: name
Expected: Jürgen
     got: Jürgen

You can find a sample Spring Boot project to reproduce the problem at https://github.com/sgybas/mockmvc-json-utf8

There was a similar issue for jsonPath() (#23219).

[cbartolome]

Both overloads of ContentResultMatchers.string() do this, too. Three other functions in that class call getContentAsString() with no arguments, but I'm not sure if that results in the same issue.

[chrisaige]

I use getContentAsString() and mockMvc seems to return my Content as ISO 8859-1.
Before (with Spring Boot 2.1.9) it was proper UTF-8

When I add a produces to my Endpoint like @GetMapping(value = "/test", produces={"application/json; charset=UTF-8"}) it works as indented.
But I dont want to go throught all my endpoints todo this.

[rstoyanchev]

In your tests use ContentResultMatchers#json(String).