Fix an error for Minitest/AssertOperator and Minitest/RefuteOperator

This PR fixes an error for `Minitest/AssertOperator` and `Minitest/RefuteOperator`
when using unary operation argument.

changelog/fix_an_error_for_assert_operator_and_refute_operator.md

@@ -0,0 +1 @@
+* [#263](https://github.com/rubocop/rubocop-minitest/pull/263): Fix an error for `Minitest/AssertOperator` and `Minitest/RefuteOperator` when using unary operation argument. ([@koic][])

lib/rubocop/cop/minitest/assert_operator.rb

@@ -21,7 +21,7 @@ class AssertOperator < Base
 
         def on_send(node)
           first_argument = node.first_argument
-          return unless first_argument.respond_to?(:operator_method?) && first_argument.operator_method?
+          return unless first_argument.respond_to?(:binary_operation?) && first_argument.binary_operation?
 
           new_arguments = build_new_arguments(node)
 

lib/rubocop/cop/minitest/refute_operator.rb

@@ -21,7 +21,7 @@ class RefuteOperator < Base
 
         def on_send(node)
           first_argument = node.first_argument
-          return unless first_argument.respond_to?(:operator_method?) && first_argument.operator_method?
+          return unless first_argument.respond_to?(:binary_operation?) && first_argument.binary_operation?
 
           new_arguments = build_new_arguments(node)
 

test/rubocop/cop/minitest/assert_operator_test.rb

@@ -81,4 +81,14 @@ def test_do_something
       end
     RUBY
   end
+
+  def test_does_not_register_offense_when_using_assert_with_unary_operation
+    assert_no_offenses(<<~RUBY)
+      class FooTest < Minitest::Test
+        def test_do_something
+          assert(-x)
+        end
+      end
+    RUBY
+  end
 end

test/rubocop/cop/minitest/refute_operator_test.rb

@@ -81,4 +81,14 @@ def test_do_something
       end
     RUBY
   end
+
+  def test_does_not_register_offense_when_using_refute_with_unary_operation
+    assert_no_offenses(<<~RUBY)
+      class FooTest < Minitest::Test
+        def test_do_something
+          refute(-x)
+        end
+      end
+    RUBY
+  end
 end