Fix a false negative for Minitest/EmptyLineBeforeAssertionMethods

Fixes part of #189.

This PR fixes a false negative for `Minitest/EmptyLineBeforeAssertionMethods`
when using non assertion method statement before assertion method used in a block.

changelog/fix_false_negative_for_minitest_empty_line_before_assertion_methods.md

@@ -0,0 +1 @@
+* [#189](https://github.com/rubocop/rubocop-minitest/issues/189): Fix a false negative for `Minitest/EmptyLineBeforeAssertionMethods` when using non assertion method statement before assertion method used in a block. ([@koic][])

lib/rubocop/cop/minitest/empty_line_before_assertion_methods.rb

@@ -23,19 +23,27 @@ class EmptyLineBeforeAssertionMethods < Base
         MSG = 'Add empty line before assertion.'
 
         def on_send(node)
-          return unless assertion_method?(node)
-          return unless (previous_line_node = node.left_sibling)
+          return unless (assertion_method = assertion_method(node))
+          return unless (previous_line_node = assertion_method.left_sibling)
           return unless previous_line_node.is_a?(RuboCop::AST::Node)
-          return if accept_previous_line?(previous_line_node, node)
+          return if accept_previous_line?(previous_line_node, assertion_method)
 
           previous_line_node = previous_line_node.arguments.last if use_heredoc_argument?(previous_line_node)
-          return unless no_empty_line?(previous_line_node, node)
+          return unless no_empty_line?(previous_line_node, assertion_method)
 
-          register_offense(node, previous_line_node)
+          register_offense(assertion_method, previous_line_node)
         end
 
         private
 
+        def assertion_method(node)
+          if assertion_method?(node)
+            node
+          elsif node.parent&.block_type? && assertion_method?(node.parent.body)
+            node.parent
+          end
+        end
+
         def accept_previous_line?(previous_line_node, node)
           return true if previous_line_node.args_type? || node.parent.basic_conditional?
 

test/project_test.rb

@@ -22,6 +22,7 @@ def test_changelog_has_either_entries_headers_or_empty_lines
 
   def test_changelog_has_link_definitions_for_all_implicit_links
     implicit_link_names = @changelog.scan(/\[([^\]]+)\]\[\]/).flatten.uniq
+
     implicit_link_names.each do |name|
       assert_includes(
         @changelog, "[#{name}]: http",

test/rubocop/cop/minitest/empty_line_before_assertion_methods_test.rb

@@ -109,6 +109,46 @@ def test_do_something
     RUBY
   end
 
+  def test_registers_offense_when_using_statement_before_assertion_method_used_in_block
+    assert_offense(<<~RUBY)
+      def test_do_something
+        set = Set.new([1,2,3])
+        set.each do |thing|
+        ^^^^^^^^^^^^^^^^^^^ Add empty line before assertion.
+          refute_nil(thing)
+        end
+      end
+    RUBY
+
+    assert_correction(<<~RUBY)
+      def test_do_something
+        set = Set.new([1,2,3])
+
+        set.each do |thing|
+          refute_nil(thing)
+        end
+      end
+    RUBY
+  end
+
+  def test_registers_offense_when_using_statement_before_single_line_assertion_method_used_in_block
+    assert_offense(<<~RUBY)
+      def test_do_something
+        set = Set.new([1,2,3])
+        set.each { |thing| refute_nil(thing) }
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Add empty line before assertion.
+      end
+    RUBY
+
+    assert_correction(<<~RUBY)
+      def test_do_something
+        set = Set.new([1,2,3])
+
+        set.each { |thing| refute_nil(thing) }
+      end
+    RUBY
+  end
+
   def test_does_not_register_offense_when_using_empty_line_before_assertion_methods
     assert_no_offenses(<<~RUBY)
       def test_do_something
@@ -173,4 +213,34 @@ def test_do_something
       end
     RUBY
   end
+
+  def test_registers_offense_when_using_assertion_method_before_assertion_method_used_in_block
+    assert_no_offenses(<<~RUBY)
+      def test_do_something
+        set = Set.new([1,2,3])
+
+        refute_nil(set)
+        set.each do |thing|
+          refute_nil(thing)
+        end
+      end
+    RUBY
+  end
+
+  def test_does_not_register_offense_when_using_statement_before_non_assertion_method_used_in_block
+    assert_no_offenses(<<~RUBY)
+      def test_do_something
+        set = Set.new([1,2,3])
+        set.each do |thing|
+          do_something(thing)
+        end
+      end
+    RUBY
+  end
+
+  def test_does_not_register_offense_when_using_only_non_assertion_method
+    assert_no_offenses(<<~RUBY)
+      do_something(thing)
+    RUBY
+  end
 end