Update InstanceVariables linter to support :ruby filters

CHANGELOG.md

@@ -1,5 +1,7 @@
 # HAML-Lint Changelog
 
+* Update `InstanceVariables` linter to support :ruby filters
+
 ### 0.59.0
 
 * Speed up load time by preferring `require_relative` in internal gem file loading

lib/haml_lint/linter/instance_variables.rb

@@ -21,7 +21,7 @@ def visit_script(node)
       return unless enabled?
 
       if node.parsed_script.contains_instance_variables?
-        record_lint(node, "Avoid using instance variables in #{file_types} views")
+        record_lint(node, failure_message)
       end
     end
 
@@ -41,10 +41,27 @@ def visit_tag(node)
 
       visit_script(node) ||
         if node.parsed_attributes.contains_instance_variables?
-          record_lint(node, "Avoid using instance variables in #{file_types} views")
+          record_lint(node, failure_message)
         end
     end
 
+    # Checks for instance variables in :ruby filters when the linter is enabled.
+    #
+    # @param [HamlLint::Tree::FilterNode]
+    # @return [void]
+    def visit_filter(node)
+      return unless enabled?
+      return unless node.filter_type == 'ruby'
+      return unless ast = parse_ruby(node.text)
+
+      ast.each_node do |i|
+        if i.type == :ivar
+          record_lint(node, failure_message)
+          break
+        end
+      end
+    end
+
     private
 
     # Tracks whether the linter is enabled for the file.
@@ -75,5 +92,13 @@ def file_types
     def matcher
       @matcher ||= Regexp.new(config['matchers'][file_types] || '\A_.*\.haml\z')
     end
+
+    # The error message when an ivar is found
+    #
+    # @api private
+    # @return [String]
+    def failure_message
+      "Avoid using instance variables in #{file_types} views"
+    end
   end
 end

spec/haml_lint/linter/instance_variables_spec.rb

@@ -4,7 +4,14 @@
   include_context 'linter'
 
   context 'when the file name does not match the matcher' do
-    let(:haml) { '%p= @greeting' }
+    let(:haml) do
+      [
+        '%p= @greeting',
+        '%p{ title: @greeting }',
+        ':ruby',
+        '  x = @greeting'
+      ].join("\n")
+    end
 
     it { should_not report_lint }
   end
@@ -222,6 +229,17 @@
 
         it { should report_lint line: 2 }
       end
+
+      context 'in a :ruby filter' do
+        let(:haml) do
+          [
+            ':ruby',
+            '  foo = @greeting',
+          ].join("\n")
+        end
+
+        it { should report_lint line: 1 }
+      end
     end
   end