Add trace tests

lib/debug/session.rb

@@ -499,7 +499,6 @@ def process_command line
         case arg
         when 'on'
           dir = __dir__
-          i = 0
           @tracer ||= TracePoint.new(:call, :return, :b_call, :b_return, :line, :class, :end){|tp|
             next if File.dirname(tp.path) == dir
             next if tp.path == '<internal:trace_point>'

test/debug/trace_test.rb

@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require_relative '../support/test_case'
+
+module DEBUGGER__
+  class TraceTest < TestCase
+    def program
+      <<~RUBY
+     1| def foo
+     2|   10
+     3| end
+     4|
+     5| a = 1
+     6| foo + a
+     7|
+     8| binding.bp
+     9| __END__
+      RUBY
+    end
+
+    def test_trace_on_starts_tracing
+      debug_code(program) do
+        type "trace on"
+        type "continue"
+
+        trace_regexps = [
+          /Tracing:   line at .*rb:5\r\n/,
+          /Tracing:   line at .*rb:6\r\n/,
+          /Tracing:   call Object#foo at .*rb:1\r\n/,
+          /Tracing:   line at .*rb:2\r\n/,
+          /Tracing:   return Object#foo => 10 at .*rb:3\r\n/,
+          /Tracing:   line at .*rb:8\r\n/,
+        ]
+        assert_line_text(Regexp.union(trace_regexps))
+
+        type "q!"
+      end
+    end
+
+    def test_trace_off_stops_tracing
+      debug_code(program) do
+        type "b 5"
+        type "trace on"
+        type "continue"
+
+        trace_regexps = [
+          /Tracing:   line at .*rb:5\r\n/,
+          /Tracing:   line at .*rb:6\r\n/,
+        ]
+
+        assert_line_text(Regexp.union(trace_regexps))
+
+        type "trace off"
+        assert_no_line_text(/Tracing:   call Object#foo at .*rb:1\r\n/)
+
+        type "q!"
+      end
+    end
+  end
+end

test/support/assertions.rb

@@ -11,12 +11,33 @@ def assert_line_num(expected)
 
     def assert_line_text(expected)
       @queue.push(Proc.new {
-        result = @last_backlog[1..].join
+        result = collect_recent_backlog
         expected = Regexp.escape(expected) if expected.is_a?(String)
         msg = "Expected to include `#{expected}` in\n(\n#{result})\n"
-        assert_block(MessageCreationController.new { create_message(msg) }) { result.match? expected }
+
+        assert_block(MessageCreationController.new { create_message(msg) }) do
+          result.match? expected
+        end
+      })
+    end
+
+    def assert_no_line_text(expected)
+      @queue.push(Proc.new {
+        result = collect_recent_backlog
+        expected = Regexp.escape(expected) if expected.is_a?(String)
+        msg = "Expected not to include `#{expected}` in\n(\n#{result})\n"
+
+        assert_block(MessageCreationController.new { create_message(msg) }) do
+          !result.match? expected
+        end
       })
     end
+
+    private
+
+    def collect_recent_backlog
+      @last_backlog[1..].join
+    end
   end
 end