Add SnippetExtractor spec examples for end-less methods support

Ref: #2892

Author: yujinakayama

spec/rspec/core/formatters/snippet_extractor_spec.rb

@@ -1,7 +1,11 @@
 require 'rspec/core/formatters/snippet_extractor'
+require 'support/helper_methods'
+require 'tempfile'
 
 module RSpec::Core::Formatters
   RSpec.describe SnippetExtractor do
+    include RSpecHelpers
+
     subject(:expression_lines) do
       SnippetExtractor.extract_expression_lines_at(file_path, line_number, max_line_count)
     end
@@ -182,6 +186,62 @@ def obj.foo(arg)
         end
       end
 
+      context 'when the expression line includes an "end"-less method definition', :if => RUBY_VERSION.to_f >= 3.0 do
+        include RSpec::Support::InSubProcess
+
+        let(:source) do
+          in_sub_process do
+            load(file.path)
+          end
+        end
+
+        let(:file) do
+          file = Tempfile.new('source.rb')
+
+          file.write(unindent(<<-END))
+            obj = Object.new
+
+            def obj.foo = raise
+
+            obj.foo
+          END
+
+          file.close
+
+          file
+        end
+
+        after do
+          file.unlink
+        end
+
+        it 'returns only the line' do
+          expect(expression_lines).to eq([
+            'def obj.foo = raise'
+          ])
+        end
+      end
+
+      context 'when the expression is a setter method definition', :unless => argument_error_points_invoker do
+        let(:source) do
+          obj = Object.new
+
+          def obj.foo=(arg1, arg2)
+            @foo = arg1
+          end
+
+          obj.foo = 1
+        end
+
+        it 'returns all the lines without confusing it with "end"-less method' do
+          expect(expression_lines).to eq([
+            '          def obj.foo=(arg1, arg2)',
+            '            @foo = arg1',
+            '          end'
+          ])
+        end
+      end
+
       context "when the expression ends with multiple paren-only lines of same type" do
         let(:source) do
           do_something_fail(:foo, (:bar

spec/support/aruba_support.rb

@@ -1,3 +1,5 @@
+require 'support/helper_methods'
+
 if RSpec::Support::Ruby.jruby? && RSpec::Support::Ruby.jruby_version == "9.1.17.0"
   # A regression appeared in require_relative in JRuby 9.1.17.0 where require some
   # how ends up private, this monkey patch uses `send`
@@ -29,6 +31,7 @@ module ArubaLoader
 
 RSpec.shared_context "aruba support" do
   include Aruba::Api
+  include RSpecHelpers
   let(:stderr) { StringIO.new }
   let(:stdout) { StringIO.new }
 
@@ -70,13 +73,6 @@ def write_file_formatted(file_name, contents)
     formatted_contents = unindent(contents.sub(/\A\n/, ""))
     write_file file_name, formatted_contents
   end
-
-  # Intended for use with indented heredocs.
-  # taken from Ruby Tapas:
-  # https://rubytapas.dpdcart.com/subscriber/post?id=616#files
-  def unindent(s)
-    s.gsub(/^#{s.scan(/^[ \t]+(?=\S)/).min}/, "")
-  end
 end
 
 RSpec.configure do |c|

spec/support/helper_methods.rb

@@ -14,6 +14,13 @@ def ignoring_warnings
     result
   end
 
+  # Intended for use with indented heredocs.
+  # taken from Ruby Tapas:
+  # https://rubytapas.dpdcart.com/subscriber/post?id=616#files
+  def unindent(s)
+    s.gsub(/^#{s.scan(/^[ \t]+(?=\S)/).min}/, "")
+  end
+
   # In Ruby 2.7 taint was removed and has no effect, whilst SAFE warns that it
   # has no effect and will become a normal varible in 3.0. Other engines do not
   # implement SAFE.