Add test for instance variable ordering in DAP

PR ruby#806 sorts instance variables by name before returning them. This
commit adds a test that verifies this functionality under the DAP
protocol.

Author: egiurleo

test/protocol/variables_test.rb

@@ -56,4 +56,30 @@ def test_eval_evaluates_global_variables
       end
     end
   end
+
+  class DAPInstanceVariableTest < ProtocolTestCase
+    PROGRAM = <<~RUBY
+      1| @a = 1
+      2| @c = 3
+      3| @b = 2
+      4| @z = 4
+    RUBY
+
+    def test_ordering_instance_variables
+      run_protocol_scenario PROGRAM, cdp: false do
+        req_add_breakpoint 4
+        req_continue
+
+        locals = gather_variables
+
+        variables_reference = locals.find { |local| local[:name] == "%self" }[:variablesReference]
+        res = send_dap_request 'variables', variablesReference: variables_reference
+
+        instance_vars = res.dig(:body, :variables)
+        assert_equal instance_vars.map { |var| var[:name] }, ["#class", "@a", "@b", "@c"]
+
+        req_terminate_debuggee
+      end
+    end
+  end
 end

test/support/protocol_test_case.rb

@@ -224,7 +224,7 @@ def gather_variables(frame_idx: 0, type: "locals")
 
         # get variables
         res = send_dap_request 'variables', variablesReference: locals_reference
-        res.dig(:body, :variables).map { |loc| { name: loc[:name], value: loc[:value], type: loc[:type] } }
+        res.dig(:body, :variables).map { |loc| { name: loc[:name], value: loc[:value], type: loc[:type], variablesReference: loc[:variablesReference] } }
       when 'chrome'
         current_frame = @crt_frames.first
         locals_scope = current_frame[:scopeChain].find { |f| f[:type] == type }
@@ -1073,4 +1073,3 @@ def parse_ k, v
     end
   end
 end
-