Add AllowedPatterns configuration option to `RSpec/NoExpectationExa…

…mple`

Fix: rubocop#1385

This cop can be customized allowed expectation methods pattern
with `AllowedPatterns`. \Aexpect_ and \Aassert_ are allowed by default.

### @ example `AllowedPatterns: [\Aexpect_]`
```ruby
# bad
it do
  not_expect_something
end

# good
it do
  expect_something
end
```

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Add `require_implicit` style to `RSpec/ImplicitSubject`. ([@r7kamura][])
 * Fix a false positive for `RSpec/Capybara/SpecificMatcher` when `have_css("a")` without attribute. ([@ydah][])
+* Add `AllowedPatterns` configuration option to `RSpec/NoExpectationExample`.  ([@ydah][])
 
 ## 2.13.2 (2022-09-23)
 

config/default.yml

@@ -641,7 +641,11 @@ RSpec/NoExpectationExample:
   Enabled: pending
   Safe: false
   VersionAdded: '2.13'
+  VersionChanged: '2.14'
   Reference: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NoExpectationExample
+  AllowedPatterns:
+    - "\\Aexpect_"
+    - "\\Aassert_"
 
 RSpec/NotToNot:
   Description: Checks for consistent method usage for negating expectations.

docs/modules/ROOT/pages/cops_rspec.adoc

@@ -3503,7 +3503,7 @@ end
 | No
 | No
 | 2.13
-| -
+| 2.14
 |===
 
 Checks if an example contains any expectation.
@@ -3520,6 +3520,9 @@ add the following configuration:
       Expectations:
         - custom_expect
 
+This cop can be customized allowed expectation methods pattern
+with `AllowedPatterns`. \Aexpect_ and \Aassert_ are allowed by default.
+
 === Examples
 
 [source,ruby]
@@ -3535,6 +3538,44 @@ it do
 end
 ----
 
+==== `AllowedPatterns` configuration
+
+[source,ruby]
+----
+# .rubocop.yml
+# RSpec/NoExpectationExample:
+#   AllowedPatterns:
+#     - \Aexpect_
+#     - \Aassert_
+----
+
+[source,ruby]
+----
+# bad
+it do
+  not_expect_something
+end
+
+# good
+it do
+  expect_something
+end
+
+it do
+  assert_something
+end
+----
+
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| AllowedPatterns
+| `\Aexpect_`, `\Aassert_`
+| Array
+|===
+
 === References
 
 * https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/NoExpectationExample

lib/rubocop/cop/rspec/no_expectation_example.rb

@@ -28,7 +28,34 @@ module RSpec
       #     expect(a?).to be(true)
       #   end
       #
+      # This cop can be customized allowed expectation methods pattern
+      # with `AllowedPatterns`. \Aexpect_ and \Aassert_ are allowed by default.
+      #
+      # @example `AllowedPatterns` configuration
+      #
+      #   # .rubocop.yml
+      #   # RSpec/NoExpectationExample:
+      #   #   AllowedPatterns:
+      #   #     - \Aexpect_
+      #   #     - \Aassert_
+      #
+      # @example
+      #   # bad
+      #   it do
+      #     not_expect_something
+      #   end
+      #
+      #   # good
+      #   it do
+      #     expect_something
+      #   end
+      #
+      #   it do
+      #     assert_something
+      #   end
+      #
       class NoExpectationExample < Base
+        include AllowedPattern
         MSG = 'No expectation found in this example.'
 
         # @!method regular_or_focused_example?(node)
@@ -61,11 +88,22 @@ def on_block(node)
           return unless regular_or_focused_example?(node)
           return if including_any_expectation?(node)
           return if including_any_skip_example?(node)
+          return if including_any_allowed_pattern?(node)
 
           add_offense(node)
         end
 
         alias on_numblock on_block
+
+        private
+
+        def including_any_allowed_pattern?(node)
+          node.each_descendant(:send) do |send_node|
+            return true if matches_allowed_pattern?(send_node.method_name)
+          end
+
+          false
+        end
       end
     end
   end

spec/rubocop/cop/rspec/no_expectation_example_spec.rb

@@ -137,6 +137,39 @@
     end
   end
 
+  context 'when `AllowedPatterns: [\Aexpect_]`' do
+    let(:cop_config) { { 'AllowedPatterns' => ['\Aexpect_'] } }
+
+    context 'with only allowed pattern methods are used' do
+      it 'registers no offenses' do
+        expect_no_offenses(<<~RUBY)
+          it { expect_something }
+        RUBY
+      end
+    end
+
+    context 'with allowed pattern methods and other method are used' do
+      it 'registers no offenses' do
+        expect_no_offenses(<<~RUBY)
+          it do
+            do_something
+            expect_something
+            do_something
+          end
+        RUBY
+      end
+    end
+
+    context 'with only not allowed pattern methods are used' do
+      it 'does something' do
+        expect_offense(<<~RUBY)
+          it { not_expect_something }
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ No expectation found in this example.
+        RUBY
+      end
+    end
+  end
+
   context 'when Ruby 2.7', :ruby27 do
     context 'with no expectation example with it' do
       it 'registers an offense' do