Merge pull request #262 from koic/fix_an_error_for_assert_operator

[Fix #261] Fix an error for `Minitest/AssertOperator`

changelog/fix_an_error_for_assert_operator.md

@@ -0,0 +1 @@
+* [#261](https://github.com/rubocop/rubocop-minitest/issues/261): Fix an error for `Minitest/AssertOperator` and `Minitest/RefuteOperator` when using variable argument. ([@koic][])

lib/rubocop/cop/minitest/assert_operator.rb

@@ -20,7 +20,8 @@ class AssertOperator < Base
         RESTRICT_ON_SEND = %i[assert].freeze
 
         def on_send(node)
-          return unless node.first_argument.operator_method?
+          first_argument = node.first_argument
+          return unless first_argument.respond_to?(:operator_method?) && first_argument.operator_method?
 
           new_arguments = build_new_arguments(node)
 

lib/rubocop/cop/minitest/refute_operator.rb

@@ -20,7 +20,8 @@ class RefuteOperator < Base
         RESTRICT_ON_SEND = %i[refute].freeze
 
         def on_send(node)
-          return unless node.first_argument.operator_method?
+          first_argument = node.first_argument
+          return unless first_argument.respond_to?(:operator_method?) && first_argument.operator_method?
 
           new_arguments = build_new_arguments(node)
 

test/rubocop/cop/minitest/assert_operator_test.rb

@@ -69,4 +69,16 @@ def test_do_something
       end
     RUBY
   end
+
+  def test_does_not_register_offense_when_using_assert_with_variable
+    assert_no_offenses(<<~RUBY)
+      class FooTest < Minitest::Test
+        def test_do_something
+          var = do_something
+
+          assert(var)
+        end
+      end
+    RUBY
+  end
 end

test/rubocop/cop/minitest/refute_operator_test.rb

@@ -69,4 +69,16 @@ def test_do_something
       end
     RUBY
   end
+
+  def test_does_not_register_offense_when_using_refute_with_variable
+    assert_no_offenses(<<~RUBY)
+      class FooTest < Minitest::Test
+        def test_do_something
+          var = do_something
+
+          refute(var)
+        end
+      end
+    RUBY
+  end
 end