rspec/rules/S7046/dart/rule.adoc

Extension identifier, when present, should be in PascalCase.

== Why is this an issue?

Extensions are a way to add functionality to existing classes. As such, they contain methods, getters, and setters, in the same way classes do. 

Therefore, it makes sense to adopt the same naming convention as for classes, which is https://en.wikipedia.org/wiki/Camel_case[PascalCase] (a.k.a. UpperCamelCase). 

This makes the code more homogeneous and doesn't mislead developers into thinking that the extension is a variable or a function.

== How to fix it

=== Code examples

==== Noncompliant code example

[source,dart,diff-id=1,diff-type=noncompliant]
----
extension my_extension on String { // lower_snake_case
  void myMethod() {
    print('Hello');
  }
}
----

==== Compliant solution

[source,dart,diff-id=1,diff-type=compliant]
----
extension MyExtension on String { // UpperCamelCase
  void myMethod() {
    print('Hello');
  }
}
----

== Resources

=== Documentation

* Dart Docs - https://dart.dev/tools/linter-rules/camel_case_extensions[Dart Linter rule - camel_case_extensions]
* Dart Docs - https://dart.dev/language/extension-methods[Language - extension methods]
* Wikipedia - https://en.wikipedia.org/wiki/Camel_case[Camel case]

=== Related rules

* S101 - Class names should comply with a naming convention

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

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

=== Message

* The extension name '<extension identifier>' isn't an UpperCamelCase identifier.

=== Highlighting

* The identifier of the extension.

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

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