3 files changed, 104 insertions, 1 deletions
diff --git a/test/irb/test_context.rb b/test/irb/test_context.rb
index dad819b4c1..a761521691 100644
--- a/test/irb/test_context.rb
+++ b/test/irb/test_context.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: false
 require 'tempfile'
 require 'irb'
-require 'rubygems' if defined?(Gem)
+require 'rubygems'
 
 require_relative "helper"
 
diff --git a/test/irb/test_init.rb b/test/irb/test_init.rb
index 0365098132..64bd96d022 100644
--- a/test/irb/test_init.rb
+++ b/test/irb/test_init.rb
@@ -216,6 +216,12 @@ module TestIRB
       assert_equal(['-f'], argv)
     end
 
+    def test_option_tracer
+      argv = %w[--tracer]
+      IRB.setup(eval("__FILE__"), argv: argv)
+      assert_equal(true, IRB.conf[:USE_TRACER])
+    end
+
     private
 
     def with_argv(argv)
diff --git a/test/irb/test_tracer.rb b/test/irb/test_tracer.rb
new file mode 100644
index 0000000000..f8da066b63
--- /dev/null
+++ b/test/irb/test_tracer.rb
@@ -0,0 +1,97 @@
+# frozen_string_literal: false
+require 'tempfile'
+require 'irb'
+require 'rubygems'
+
+require_relative "helper"
+
+module TestIRB
+  class ContextWithTracerIntegrationTest < IntegrationTestCase
+    def setup
+      super
+
+      @envs.merge!("NO_COLOR" => "true", "RUBY_DEBUG_HISTORY_FILE" => '')
+    end
+
+    def example_ruby_file
+      <<~'RUBY'
+        class Foo
+          def self.foo
+            100
+          end
+        end
+
+        def bar(obj)
+          obj.foo
+        end
+
+        binding.irb
+      RUBY
+    end
+
+    def test_use_tracer_is_disabled_by_default
+      write_rc <<~RUBY
+        IRB.conf[:USE_TRACER] = false
+      RUBY
+
+      write_ruby example_ruby_file
+
+      output = run_ruby_file do
+        type "bar(Foo)"
+        type "exit!"
+      end
+
+      assert_nil IRB.conf[:USER_TRACER]
+      assert_not_include(output, "#depth:")
+      assert_not_include(output, "Foo.foo")
+    end
+
+    def test_use_tracer_enabled_when_gem_is_unavailable
+      begin
+        gem 'tracer'
+        omit "Skipping because 'tracer' gem is available."
+      rescue Gem::LoadError
+        write_rc <<~RUBY
+          IRB.conf[:USE_TRACER] = true
+        RUBY
+
+        write_ruby example_ruby_file
+
+        output = run_ruby_file do
+          type "bar(Foo)"
+          type "exit!"
+        end
+
+        assert_include(output, "Tracer extension of IRB is enabled but tracer gem wasn't found.")
+      end
+    end
+
+    def test_use_tracer_enabled_when_gem_is_available
+      if Gem::Version.new(RUBY_VERSION) < Gem::Version.new('3.1.0')
+        omit "Ruby version before 3.1.0 does not support Tracer integration. Skipping this test."
+      end
+
+      begin
+        gem 'tracer'
+      rescue Gem::LoadError
+        omit "Skipping because 'tracer' gem is not available. Enable with WITH_TRACER=true."
+      end
+
+      write_rc <<~RUBY
+        IRB.conf[:USE_TRACER] = true
+      RUBY
+
+      write_ruby example_ruby_file
+
+      output = run_ruby_file do
+        type "bar(Foo)"
+        type "exit!"
+      end
+
+      assert_include(output, "Object#bar at")
+      assert_include(output, "Foo.foo at")
+      assert_include(output, "Foo.foo #=> 100")
+      assert_include(output, "Object#bar #=> 100")
+    end
+  end
+end