## Why is this an issue?

Assertions comparing an object to itself are more likely to be bugs due to developer’s carelessness.

This rule raises an issue when the actual expression matches the expected expression.

### Noncompliant code example

    assertThat(actual).isEqualTo(actual); // Noncompliant

### Compliant solution

    assertThat(actual).isEqualTo(expected);

### Exceptions

In a unit test validating the `equals(...)` and `hashCode()` methods, it’s legitimate to compare an object to itself. This rule does not raise an issue for `isEqualTo`, `assertEquals` or `hasSameHashCodeAs` when the unit test name contains (case insensitive): `equal`, `hash_?code`, `object_?method`. For example, in tests with the following names: `test_equals`, `testEqual`, `test_hashCode`, `test_hash_code`, `test_object_methods`.

    class MyClassTest {
      @Test
      void test_equals_and_hash_code() {
        MyClass obj = new MyClass();
        assertThat(obj).isEqualTo(obj); // Compliant
        assertThat(obj).hasSameHashCodeAs(obj); // Compliant
      }
    }