Calling ``++unittest++`` methods ``++assertEqual++``, ``++assertNotEqual++``, ``++assertIs++`` or ``++assertIsNot++`` on objects of incompatible types will always fail or always succeed.

For methods ``++assertEqual++`` and ``++assertNotEqual++``, arguments' types are incompatible if:

    they are unrelated builtin types such as string and integer.
    they are instances of unrelated classes which do not implement ``++__eq__++`` or ``++__ne__++`` (if a class implements one of these methods it could compare to any other type it wants).

As for methods ``++assertIs++`` and ``++assertIsNot++``, if arguments' types are different it is not possible for them to point to the same object, thus ``++assertIs++`` will always fail and ``++assertIsNot++`` will always succeed.

== Noncompliant Code Example

----
import unittest
class A(): ...
class MyTest(unittest.TestCase):
  def test_something(self):
    a = A()
    mydict = {"x": a}
    self.assertEqual(a, "x")  # Noncompliant
    self.assertIs(a, "x")  # Noncompliant
----

== Compliant Solution

----
import unittest
class A(): ...
class MyTest(unittest.TestCase):
  def test_something(self):
    a = A()
    mydict = {"x": a}
    self.assertEqual(a, mydict["x"])  # OK
    self.assertIs(a, mydict["x"])  # OK
----

== See

* S2159 Silly equality checks should not be made
* S3403 Identity operators should not be used with dissimilar types