rspec/rules/S3699/python/rule.adoc

This rule raises an issue when a function call result is used, even though the function does not return anything.

== Why is this an issue?

If a function does not return anything, it makes no sense to use its output. Specifically, passing it to another function, or assigning its "result" to a variable is probably a bug because such functions return nothing, which is probably not what was intended.

=== Code examples

==== Noncompliant code example

[source,python,diff-id=1,diff-type=noncompliant]
----
def foo():
  l = [1, 2, 3]
  result = l.append(42) # Noncompliant, `append` mutates list l
  return result
----

==== Compliant solution

[source,python,diff-id=1,diff-type=compliant]
----
def foo():
  l = [1, 2, 3]
  l.append(42)
  return l
----

== Resources

=== Documentation

* Python documentation - https://docs.python.org/3/tutorial/controlflow.html#defining-functions[Defining Functions]
ifdef::env-github,rspecator-view[]

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

include::../message.adoc[]

include::../highlighting.adoc[]

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

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

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