Merge pull request #285 from koic/fix_an_error_for_minitest_multiple_assertions

[Fix #283] Fix an error for `Minitest/MultipleAssertions`

Author: koic

changelog/fix_an_error_for_minitest_multiple_assertions.md

@@ -0,0 +1 @@
+* [#283](https://github.com/rubocop/rubocop-minitest/issues/283): Fix an error for `Minitest/MultipleAssertions` when using `||` assigning a value to a variable. ([@koic][])

lib/rubocop/cop/mixin/minitest_exploration_helpers.rb

@@ -99,8 +99,9 @@ def assertions_count(node)
         end
       end
 
-      # rubocop:disable Metrics/CyclomaticComplexity
+      # rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
       def assertion_method?(node)
+        return false unless node
         return assertion_method?(node.expression) if node.assignment? && node.respond_to?(:expression)
         return false if !node.send_type? && !node.block_type? && !node.numblock_type?
 
@@ -110,7 +111,7 @@ def assertion_method?(node)
           method_name.start_with?(prefix) || node.method?(:flunk)
         end
       end
-      # rubocop:enable Metrics/CyclomaticComplexity
+      # rubocop:enable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
 
       def lifecycle_hook_method?(node)
         node.def_type? && LIFECYCLE_HOOK_METHODS.include?(node.method_name)

test/rubocop/cop/minitest/multiple_assertions_test.rb

@@ -113,6 +113,18 @@ def test_asserts_once
     RUBY
   end
 
+  def test_does_not_register_offense_when_using_or_assigning_a_value_to_an_object_attribute
+    assert_no_offenses(<<~RUBY)
+      class FooTest < Minitest::Test
+        def test_asserts_once
+          var ||= :value
+
+          assert_equal(foo, bar)
+        end
+      end
+    RUBY
+  end
+
   def test_generates_a_todo_based_on_the_worst_violation
     inspect_source(<<-RUBY, @cop, 'test/foo_test.rb')
       class FooTest < Minitest::Test