Add cop to enfore refute_empty over refute(actual.empty?)

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### New features
 
 * [#15](https://github.com/rubocop-hq/rubocop-minitest/pull/15): Add new `Minitest/RefuteIncludes` cop. ([@abhaynikam][])
+* [#20](https://github.com/rubocop-hq/rubocop-minitest/pull/20): Add new `Minitest/RefuteEmpty` cop. ([@abhaynikam][])
 
 ### Bug fixes
 

config/default.yml

@@ -32,6 +32,12 @@ Minitest/RefuteNil:
   Enabled: true
   VersionAdded: '0.2'
 
+Minitest/RefuteEmpty:
+  Description: 'This cop enforces to use `refute_empty` instead of using `refute(object.empty?)`.'
+  StyleGuide: 'https://github.com/rubocop-hq/minitest-style-guide#refute-empty'
+  Enabled: true
+  VersionAdded: '0.3'
+
 Minitest/RefuteIncludes:
   Description: 'This cop enforces the test to use `refute_includes` instead of using `refute(collection.include?(object))`.'
   StyleGuide: 'https://github.com/rubocop-hq/minitest-style-guide#refute-includes'

lib/rubocop/cop/minitest/refute_empty.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Minitest
+      # This cop enforces to use `refute_empty` instead of
+      # using `refute(object.empty?)`.
+      #
+      # @example
+      #   # bad
+      #   refute(object.empty?)
+      #   refute(object.empty?, 'the message')
+      #
+      #   # good
+      #   refute_empty(object)
+      #   refute_empty(object, 'the message')
+      #
+      class RefuteEmpty < Cop
+        MSG = 'Prefer using `refute_empty(%<arguments>s)` over ' \
+              '`refute(%<receiver>s)`.'
+
+        def_node_matcher :refute_with_empty, <<~PATTERN
+          (send nil? :refute $(send $_ :empty?) $...)
+        PATTERN
+
+        def on_send(node)
+          refute_with_empty(node) do |first_receiver_arg, object, rest_receiver_arg|
+            message = rest_receiver_arg.first
+
+            arguments = [object.source, message&.source].compact.join(', ')
+            receiver = [first_receiver_arg.source, message&.source].compact.join(', ')
+
+            offense_message = format(MSG, arguments: arguments, receiver: receiver)
+            add_offense(node, message: offense_message)
+          end
+        end
+
+        def autocorrect(node)
+          lambda do |corrector|
+            refute_with_empty(node) do |_first_receiver_arg, object, rest_receiver_arg|
+              message = rest_receiver_arg.first
+
+              replacement = [object.source, message&.source].compact.join(', ')
+              corrector.replace(node.loc.expression, "refute_empty(#{replacement})")
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/minitest_cops.rb

@@ -4,5 +4,6 @@
 require_relative 'minitest/assert_nil'
 require_relative 'minitest/assert_includes'
 require_relative 'minitest/assert_truthy'
+require_relative 'minitest/refute_empty'
 require_relative 'minitest/refute_nil'
 require_relative 'minitest/refute_includes'

manual/cops.md

@@ -5,6 +5,7 @@
 * [Minitest/AssertIncludes](cops_minitest.md#minitestassertincludes)
 * [Minitest/AssertNil](cops_minitest.md#minitestassertnil)
 * [Minitest/AssertTruthy](cops_minitest.md#minitestasserttruthy)
+* [Minitest/RefuteEmpty](cops_minitest.md#minitestrefuteempty)
 * [Minitest/RefuteIncludes](cops_minitest.md#minitestrefuteincludes)
 * [Minitest/RefuteNil](cops_minitest.md#minitestrefutenil)
 

manual/cops_minitest.md

@@ -98,6 +98,31 @@ assert(actual, 'the message')
 
 * [https://github.com/rubocop-hq/minitest-style-guide#assert-truthy](https://github.com/rubocop-hq/minitest-style-guide#assert-truthy)
 
+## Minitest/RefuteEmpty
+
+Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+--- | --- | --- | --- | ---
+Enabled | Yes | Yes  | 0.3 | -
+
+This cop enforces to use `refute_empty` instead of
+using `refute(object.empty?)`.
+
+### Examples
+
+```ruby
+# bad
+refute(object.empty?)
+refute(object.empty?, 'the message')
+
+# good
+refute_empty(object)
+refute_empty(object, 'the message')
+```
+
+### References
+
+* [https://github.com/rubocop-hq/minitest-style-guide#refute-empty](https://github.com/rubocop-hq/minitest-style-guide#refute-empty)
+
 ## Minitest/RefuteIncludes
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged

test/rubocop/cop/minitest/refute_empty_test.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class RefuteEmptyTest < Minitest::Test
+  def setup
+    @cop = RuboCop::Cop::Minitest::RefuteEmpty.new
+  end
+
+  def test_registers_offense_when_using_refute_with_empty
+    assert_offense(<<~RUBY, @cop)
+      class FooTest < Minitest::Test
+        def test_do_something
+          refute(somestuff.empty?)
+          ^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using `refute_empty(somestuff)` over `refute(somestuff.empty?)`.
+        end
+      end
+    RUBY
+
+    assert_correction(<<~RUBY, @cop)
+      class FooTest < Minitest::Test
+        def test_do_something
+          refute_empty(somestuff)
+        end
+      end
+    RUBY
+  end
+
+  def test_registers_offense_when_using_refute_with_empty_and_message
+    assert_offense(<<~RUBY, @cop)
+      class FooTest < Minitest::Test
+        def test_do_something
+          refute(somestuff.empty?, 'the message')
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Prefer using `refute_empty(somestuff, 'the message')` over `refute(somestuff.empty?, 'the message')`.
+        end
+      end
+    RUBY
+
+    assert_correction(<<~RUBY, @cop)
+      class FooTest < Minitest::Test
+        def test_do_something
+          refute_empty(somestuff, 'the message')
+        end
+      end
+    RUBY
+  end
+
+  def refute_empty_method
+    assert_no_offenses(<<~RUBY, @cop)
+      class FooTest < Minitest::Test
+        def test_do_something
+          refute_empty(somestuff)
+        end
+      end
+    RUBY
+  end
+end