rspec/rules/S5845/python/rule.adoc

== Why is this an issue?

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

[source,python]
----
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

[source,python]
----
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
----

== Resources

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

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

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

=== Message

Primary: Change this assertion to not compare dissimilar types ("XXX" and "YYY").

Secondary: Last assignment of "ZZZ".


=== Highlighting

Primary: the arguments of the assertXXX call.

Secondaries (if args are variables): the last assignment of the variable.


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

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

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