Adjust ThreadClient's frames management for nested subsession change (r…

…uby#558)

lib/debug/thread_client.rb

@@ -85,7 +85,8 @@ def initialize id, q_evt, q_cmd, thr = Thread.current
       @is_management = false
       @id = id
       @thread = thr
-      @target_frames = nil
+      @frame_index_stack = []
+      @frames_stack = []
       @q_evt = q_evt
       @q_cmd = q_cmd
       @step_tp = nil
@@ -102,19 +103,27 @@ def initialize id, q_evt, q_cmd, thr = Thread.current
     end
 
     def target_frames
-      @target_frames
+      @frames_stack.last
     end
 
     def set_target_frames(frames)
-      @target_frames = frames
+      @frames_stack << frames
+    end
+
+    def pop_target_frames
+      @frames_stack.pop
     end
 
     def current_frame_index
-      @current_frame_index
+      @frame_index_stack.last
     end
 
     def set_current_frame_index(i)
-      @current_frame_index = i
+      @frame_index_stack << i
+    end
+
+    def pop_current_frame_index
+      @frame_index_stack.pop
     end
 
     def deactivate
@@ -305,6 +314,9 @@ def suspend event, tp = nil, bp: nil, sig: nil, postmortem_frames: nil, replay_f
       end
 
       wait_next_action
+    ensure
+      pop_target_frames
+      pop_current_frame_index
     end
 
     def replay_suspend

test/debug/break_test.rb

@@ -722,4 +722,65 @@ def test_the_path_option_supersede_skip_path_config
       end
     end
   end
+
+  class NestedBreakTest < TestCase
+    def program
+      <<~RUBY
+     1| class Foo
+     2|   def self.bar(num)
+     3|     num
+     4|   end
+     5| end
+     6|
+     7| a = 10
+     8| binding.b
+      RUBY
+    end
+
+    if RUBY_VERSION >= "3.1.0"
+      def test_method_breakpoint_can_be_triggered_inside_another_breakpoint
+        debug_code(program) do
+          type "break Foo.bar"
+          type "c"
+
+          # stops at the first breakpoint
+          assert_line_num(8)
+
+          # enters the second breakpoint
+          type "Foo.bar(a)"
+          assert_line_num(3)
+          type "num + 10"
+          assert_line_text(/20/)
+          type "c"
+
+          # returns to the first breakpoint
+          assert_line_num(8)
+          type "a + 100"
+          assert_line_text(/110/)
+
+          type "c"
+        end
+      end
+    else
+      def test_nested_breakpoint_will_be_ignored
+        debug_code(program) do
+          type "break Foo.bar"
+          type "c"
+
+          # stops at the first breakpoint
+          assert_line_num(8)
+
+          # doesn't enter the another subsession
+          type "Foo.bar(a)"
+
+          # returns to the first breakpoint
+          assert_line_num(8)
+          type "a + 100"
+          assert_line_text(/110/)
+
+          type "c"
+        end
+      end
+    end
+  end
 end