rspec/rules/S3403/python/rule.adoc

This rule raises an issue when an identity comparison operator is used to compare objects of different types.

== Why is this an issue?

Operators https://docs.python.org/3/reference/expressions.html#is-not[``++is++``] and https://docs.python.org/3/reference/expressions.html#is-not[``++is not++``] check if their operands point to the same instance, thus they will always return respectively ``++False++`` and ``++True++`` when they are used to compare objects of different types.

=== Code examples

==== Noncompliant code example

[source,python,diff-id=1,diff-type=noncompliant]
----
a = 1
b = "1"
value = a is b  # Noncompliant. Always False
value = a is not b  # Noncompliant. Always True
----

==== Compliant solution

[source,python,diff-id=1,diff-type=compliant]
----
a = 1
b = 1
value = a is b
value = a is not b
----

== Resources

=== Documentation

* Python documentation - https://docs.python.org/3/reference/expressions.html#is-not[Identity comparisons]

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

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

=== Message

Remove this ["is"|"is not"] check between types X and Y; it will always be [False|True].


include::../highlighting.adoc[]

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

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

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