== 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

[source,java]
----
assertThat(actual).isEqualTo(actual); // Noncompliant
----

=== Compliant solution

[source,java]
----
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++``.

[source,java]
----
class MyClassTest {
  @Test
  void test_equals_and_hash_code() {
    MyClass obj = new MyClass();
    assertThat(obj).isEqualTo(obj); // Compliant
    assertThat(obj).hasSameHashCodeAs(obj); // Compliant
  }
}
----

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Replace this assertion to not have the same actual and expected expression.


=== Highlighting

Primary: expected expression


Secondary: actual expression


'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]

endif::env-github,rspecator-view[]