Change show_source tests into integration tests (#793)

* Remove trailing spaces

* Migrate show_source tests to integration tests

Because show_source tests often need to define class and/or methods,
they can easily leak state to other tests. Changing them to integration
tests will ensure that they are run in a clean environment.

* Fix NoMethodError caused by SourceFinder#method_target

lib/irb/source_finder.rb

@@ -77,6 +77,8 @@ def method_target(owner_receiver, s_count, method, type)
         target_method = target_method.super_method if target_method
       end
       target_method.nil? ? nil : target_method.source_location
+    rescue NameError
+      nil
     end
   end
 end

test/irb/cmd/test_show_source.rb

@@ -0,0 +1,263 @@
+# frozen_string_literal: false
+require 'irb'
+
+require_relative "../helper"
+
+module TestIRB
+  class ShowSourceTest < IntegrationTestCase
+    def setup
+      super
+
+      write_rc <<~'RUBY'
+        IRB.conf[:USE_PAGER] = false
+      RUBY
+    end
+
+    def test_show_source
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source IRB.conf"
+        type "exit"
+      end
+
+      assert_match(%r[/irb\/init\.rb], out)
+    end
+
+    def test_show_source_alias
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "$ IRB.conf"
+        type "exit"
+      end
+
+      assert_match(%r[/irb\/init\.rb], out)
+    end
+
+    def test_show_source_string
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source 'IRB.conf'"
+        type "exit"
+      end
+
+      assert_match(%r[/irb\/init\.rb], out)
+    end
+
+    def test_show_source_method_s
+      write_ruby <<~RUBY
+        class Baz
+          def foo
+          end
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bar#foo -s"
+        type "exit"
+      end
+
+      assert_match(%r[#{@ruby_file.to_path}:2\s+def foo\r\n  end\r\n], out)
+    end
+
+    def test_show_source_method_s_with_incorrect_signature
+      write_ruby <<~RUBY
+        class Baz
+          def foo
+          end
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bar#fooo -s"
+        type "exit"
+      end
+
+      assert_match(%r[Error: Couldn't locate a super definition for Bar#fooo], out)
+    end
+
+    def test_show_source_private_method
+      write_ruby <<~RUBY
+        class Bar
+          private def foo
+          end
+        end
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bar#foo"
+        type "exit"
+      end
+
+      assert_match(%r[#{@ruby_file.to_path}:2\s+private def foo\r\n  end\r\n], out)
+    end
+
+    def test_show_source_private_singleton_method
+      write_ruby <<~RUBY
+        class Bar
+          private def foo
+          end
+        end
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "bar = Bar.new"
+        type "show_source bar.foo"
+        type "exit"
+      end
+
+      assert_match(%r[#{@ruby_file.to_path}:2\s+private def foo\r\n  end\r\n], out)
+    end
+
+    def test_show_source_method_multiple_s
+      write_ruby <<~RUBY
+        class Baz
+          def foo
+          end
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        class Bob < Bar
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bob#foo -ss"
+        type "exit"
+      end
+
+      assert_match(%r[#{@ruby_file.to_path}:2\s+def foo\r\n  end\r\n], out)
+    end
+
+    def test_show_source_method_no_instance_method
+      write_ruby <<~RUBY
+        class Baz
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bar#foo -s"
+        type "exit"
+      end
+
+      assert_match(%r[Error: Couldn't locate a super definition for Bar#foo], out)
+    end
+
+    def test_show_source_method_exceeds_super_chain
+      write_ruby <<~RUBY
+        class Baz
+          def foo
+          end
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bar#foo -ss"
+        type "exit"
+      end
+
+      assert_match(%r[Error: Couldn't locate a super definition for Bar#foo], out)
+    end
+
+    def test_show_source_method_accidental_characters
+      write_ruby <<~'RUBY'
+        class Baz
+          def foo
+          end
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "show_source Bar#foo -sddddd"
+        type "exit"
+      end
+
+      assert_match(%r[#{@ruby_file.to_path}:2\s+def foo\r\n  end], out)
+    end
+
+    def test_show_source_receiver_super
+      write_ruby <<~RUBY
+        class Baz
+          def foo
+          end
+        end
+
+        class Bar < Baz
+          def foo
+            super
+          end
+        end
+
+        binding.irb
+      RUBY
+
+      out = run_ruby_file do
+        type "bar = Bar.new"
+        type "show_source bar.foo -s"
+        type "exit"
+      end
+
+      assert_match(%r[#{@ruby_file.to_path}:2\s+def foo\r\n  end], out)
+    end
+  end
+end