Implement RubyVMSpecWalker#on_subject

lib/solargraph/rspec/ruby_vm_spec_walker.rb

@@ -27,6 +27,19 @@ def self.a_context_block?(block_ast)
           Solargraph::Rspec::CONTEXT_METHODS.include?(method_name.to_s)
         end
 
+        # @param ast [RubyVM::AbstractSyntaxTree::Node]
+        # @return [Boolean]
+        def self.a_subject_block?(block_ast)
+          return false unless a_block?(block_ast)
+
+          method_call = %i[CALL FCALL].include?(block_ast.children[0].type)
+          return false unless method_call
+
+          method_name = block_ast.children[0].children.select { |child| child.is_a?(Symbol) }.first
+
+          Solargraph::Rspec::SUBJECT_METHODS.include?(method_name.to_s)
+        end
+
         def self.a_constant?(ast)
           %i[CONST COLON2].include?(ast.type)
         end
@@ -41,6 +54,12 @@ def self.context_description_node(block_ast)
             block_ast.children[0].children[1].children[0]
           end
         end
+
+        # @param block_ast [RubyVM::AbstractSyntaxTree::Node]
+        # @return [String]
+        def self.let_method_name(block_ast)
+          block_ast.children[0].children[1]&.children&.[](0)&.children&.[](0)&.to_s
+        end
       end
 
       class RspecContextNamespace
@@ -205,17 +224,17 @@ def walk!
         #   end
         # end
 
-        # walker.on :SCOPE do |block_ast|
-        #   next if block_ast.children.first.type != :send
+        walker.on :ITER do |block_ast|
+          next unless NodeTypes.a_subject_block?(block_ast)
 
-        #   method_ast = block_ast.children.first
-        #   method_name = method_ast.children[1]
-        #   next unless Rspec::SUBJECT_METHODS.include?(method_name.to_s)
+          # method_ast = block_ast.children.first
+          method_name = NodeTypes.let_method_name(block_ast)
 
-        #   @handlers[:on_subject].each do |handler|
-        #     handler.call(method_ast, block_ast)
-        #   end
-        # end
+          @handlers[:on_subject].each do |handler|
+            method_ast = block_ast # TODO: Only use block_ast and reuse NodeTypes.let_method_name
+            handler.call(method_ast, block_ast)
+          end
+        end
 
         # walker.on :SCOPE do |block_ast|
         #   next if block_ast.children.first.type != :send

spec/solargraph/rspec/ruby_vm_spec_walker_spec.rb

@@ -34,6 +34,19 @@ def parse(code)
       end
     end
 
+    describe '.a_context_block?' do
+      it 'returns true for subject block with name' do
+        node = parse('subject(:something) { }')
+        expect(Solargraph::Rspec::RubyVMSpecWalker::NodeTypes.a_subject_block?(node.children[2])).to be(true)
+      end
+
+      it 'returns true for subject block without name' do
+        node = parse('subject { }')
+
+        expect(Solargraph::Rspec::RubyVMSpecWalker::NodeTypes.a_subject_block?(node.children[2])).to be(true)
+      end
+    end
+
     describe '.context_description_node' do
       it 'returns correct node of context description' do
         node = parse('describe "something" do end')
@@ -51,6 +64,32 @@ def parse(code)
         expect(desc.children.last).to eq(:SomeClass)
       end
     end
+
+    describe '.let_method_name' do
+      it 'returns correct method name for subject block' do
+        node = parse('subject(:something) { }')
+        name = Solargraph::Rspec::RubyVMSpecWalker::NodeTypes.let_method_name(node.children[2])
+        expect(name).to eq('something')
+      end
+
+      it 'returns nil for subject block without a name' do
+        node = parse('subject { }')
+        name = Solargraph::Rspec::RubyVMSpecWalker::NodeTypes.let_method_name(node.children[2])
+        expect(name).to eq(nil)
+      end
+
+      it 'returns correct method name for let block' do
+        node = parse('let(:something) { }')
+        name = Solargraph::Rspec::RubyVMSpecWalker::NodeTypes.let_method_name(node.children[2])
+        expect(name).to eq('something')
+      end
+
+      it 'returns nil for let block without a name' do
+        node = parse('let { }')
+        name = Solargraph::Rspec::RubyVMSpecWalker::NodeTypes.let_method_name(node.children[2])
+        expect(name).to eq(nil)
+      end
+    end
   end
 
   # @param code [String]
@@ -108,29 +147,29 @@ def walk_code(code)
   #   end
   # end
 
-  # describe '#on_subject' do
-  #   it 'yields each context block' do
-  #     code = <<~RUBY
-  #       RSpec.describe SomeClass, type: :model do
-  #         subject(:test) { SomeClass.new }
+  describe '#on_subject' do
+    it 'yields each context block' do
+      code = <<~RUBY
+        RSpec.describe SomeClass, type: :model do
+          subject(:test) { SomeClass.new }
 
-  #         context 'when something' do
-  #           subject { test }
-  #         end
-  #       end
-  #     RUBY
+          context 'when something' do
+            subject { test }
+          end
+        end
+      RUBY
 
-  #     called = 0
-  #     # @param walker [Solargraph::Rspec::SpecWalker]
-  #     walk_code(code) do |walker|
-  #       walker.on_subject do |_|
-  #         called += 1
-  #       end
-  #     end
+      called = 0
+      # @param walker [Solargraph::Rspec::SpecWalker]
+      walk_code(code) do |walker|
+        walker.on_subject do |_|
+          called += 1
+        end
+      end
 
-  #     expect(called).to eq(2)
-  #   end
-  # end
+      expect(called).to eq(2)
+    end
+  end
 
   describe '#on_each_context_block' do
     it 'yields each context block' do