Fix an error for Style/UselessAssertion when passing a single argument to methods to accept two arguments

changelog/fix_an_error_for_style_useless_assertion.md

@@ -0,0 +1 @@
+* [#299](https://github.com/rubocop/rubocop-minitest/pull/299): Fix an error for `Style/UselessAssertion` when passing a single argument to methods to accept two arguments. ([@earlopain][])

lib/rubocop/cop/minitest/useless_assertion.rb

@@ -48,7 +48,7 @@ def offense?(node)
           when *SINGLE_ASSERTION_ARGUMENT_METHODS
             actual.nil? && expected&.literal? && !expected.xstr_type?
           when *TWO_ASSERTION_ARGUMENTS_METHODS
-            return false unless expected || actual
+            return false unless expected && actual
             return false if expected.source != actual.source
 
             (expected.variable? && actual.variable?) ||

test/rubocop/cop/minitest/useless_assertion_test.rb

@@ -93,6 +93,12 @@ class UselessAssertionTest < Minitest::Test
         #{matcher} x.foo, x.foo
       RUBY
     end
+
+    define_method("test_#{matcher}_no_offense_when_only_single_argument_is_given") do
+      assert_no_offenses(<<~RUBY)
+        #{matcher} foo
+      RUBY
+    end
   end
 
   %i[assert_includes refute_includes].each do |matcher|