JUnit assertThat: check that Object equals String

The "more assertThat" way of doing things would be:

Map<String, Object> expectedData = Collections.singletonMap("key", "value");

asssertThat(data, is(expectedData));

Please note:

• Maybe you need type hints for the call to singletonMap
• Besides the is matcher, there are other matchers that would allow you to check that data contains your "expected" map data

For your specific problem: that is caused because how generics come into play here; it might be sufficient to use (String) data.get("key") - to tell the compiler that the "actual" argument is of type String.

In the end - I have no idea what your problem is. I wrote down this piece of code:

public void test() {
    Map<String, Object> data = new HashMap<>();
    data.put("key", "value");
    assertThat(data.get("key"), is("value"));

    Map<String, Object> expectedData = Collections.singletonMap("key", "value");
    assertThat(data, is(expectedData));
}

It compiles fine, and the unit test runs and passes. In other words: actually I am unable to repro your problem.