Add display tests

lib/debug/session.rb

@@ -478,9 +478,7 @@ def process_command line
         case arg
         when /(\d+)/
           if @displays[n = $1.to_i]
-            if ask "clear \##{n} #{@displays[n]}?"
-              @displays.delete_at n
-            end
+            @displays.delete_at n
           end
           @tc << [:eval, :display, @displays]
         when nil

test/debug/display_test.rb

@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require_relative '../support/test_case'
+
+module DEBUGGER__
+  class DisplayTest < TestCase
+    def program
+      <<~RUBY
+     1| a = 1
+     2| b = 2
+     3| binding.bp
+     4| __END__
+      RUBY
+    end
+
+    def test_display_displays_expressions_when_the_program_stopps
+      debug_code(program) do
+        type "display a"
+        assert_line_text(/0: a =/)
+        type "display b"
+        assert_line_text(/0: a = /)
+        assert_line_text(/1: b = /)
+        type "continue"
+        assert_line_text(/0: a = 1/)
+        assert_line_text(/1: b = 2/)
+
+        type "q!"
+      end
+    end
+
+    def test_display_without_expression_lists_display_settings
+      debug_code(program) do
+        type "display a"
+        type "display b"
+        type "display"
+        assert_line_text(/0: a = /)
+        assert_line_text(/1: b = /)
+
+        type "q!"
+      end
+    end
+
+    def test_undisplay_deletes_a_given_display_setting
+      debug_code(program) do
+        type "display a"
+        type "undisplay 0"
+        type "y"
+        type "continue"
+        assert_no_line_text(/0: a =/)
+
+        type "q!"
+      end
+    end
+
+    def test_undisplay_without_expression_deletes_all_display_settings
+      debug_code(program) do
+        type "display a"
+        type "display b"
+        type "undisplay"
+        type "y"
+        assert_no_line_text(/0: a = /)
+        assert_no_line_text(/1: b = /)
+
+        type "q!"
+      end
+    end
+  end
+end

test/support/utils.rb

@@ -29,7 +29,7 @@ def debug_code(program, **options, &block)
     end
 
     DEBUG_MODE = false
-    ASK_CMD = %w[quit delete kill]
+    ASK_CMD = %w[quit delete kill undisplay]
 
     def debug_print msg
       print msg if DEBUG_MODE