[ruby/irb] Extract integration testing helpers out of debug command

tests
(https://github.com/ruby/irb/pull/660)

The ability to run a test case in a subprocess is useful for testing
many other features, like nested IRB sessions. So I think it's worth
extracting them into a new test case class.

https://github.com/ruby/irb/commit/73b7a895f8

1 files changed, 110 insertions, 0 deletions

diff --git a/test/irb/helper.rb b/test/irb/helper.rb
index 55f9e083eb..44dd41bd1b 100644
--- a/test/irb/helper.rb
+++ b/test/irb/helper.rb
@@ -7,6 +7,11 @@ begin
 rescue LoadError # ruby/ruby defines helpers differently
 end
 
+begin
+  require "pty"
+rescue LoadError # some platforms don't support PTY
+end
+
 module IRB
   class InputMethod; end
 end
@@ -73,4 +78,109 @@ module TestIRB
       }
     end
   end
+
+  class IntegrationTestCase
+    LIB = File.expand_path("../../lib", __dir__)
+    TIMEOUT_SEC = 3
+
+    def setup
+      unless defined?(PTY)
+        omit "Integration tests require PTY."
+      end
+    end
+
+    def run_ruby_file(&block)
+      cmd = [EnvUtil.rubybin, "-I", LIB, @ruby_file.to_path]
+      tmp_dir = Dir.mktmpdir
+
+      @commands = []
+      lines = []
+
+      yield
+
+      PTY.spawn(integration_envs.merge("TERM" => "dumb"), *cmd) do |read, write, pid|
+        Timeout.timeout(TIMEOUT_SEC) do
+          while line = safe_gets(read)
+            lines << line
+
+            # means the breakpoint is triggered
+            if line.match?(/binding\.irb/)
+              while command = @commands.shift
+                write.puts(command)
+              end
+            end
+          end
+        end
+      ensure
+        read.close
+        write.close
+        kill_safely(pid)
+      end
+
+      lines.join
+    rescue Timeout::Error
+      message = <<~MSG
+      Test timedout.
+
+      #{'=' * 30} OUTPUT #{'=' * 30}
+        #{lines.map { |l| "  #{l}" }.join}
+      #{'=' * 27} END OF OUTPUT #{'=' * 27}
+      MSG
+      assert_block(message) { false }
+    ensure
+      File.unlink(@ruby_file) if @ruby_file
+      FileUtils.remove_entry tmp_dir
+    end
+
+    # read.gets could raise exceptions on some platforms
+    # https://github.com/ruby/ruby/blob/master/ext/pty/pty.c#L721-L728
+    def safe_gets(read)
+      read.gets
+    rescue Errno::EIO
+      nil
+    end
+
+    def kill_safely pid
+      return if wait_pid pid, TIMEOUT_SEC
+
+      Process.kill :TERM, pid
+      return if wait_pid pid, 0.2
+
+      Process.kill :KILL, pid
+      Process.waitpid(pid)
+    rescue Errno::EPERM, Errno::ESRCH
+    end
+
+    def wait_pid pid, sec
+      total_sec = 0.0
+      wait_sec = 0.001 # 1ms
+
+      while total_sec < sec
+        if Process.waitpid(pid, Process::WNOHANG) == pid
+          return true
+        end
+        sleep wait_sec
+        total_sec += wait_sec
+        wait_sec *= 2
+      end
+
+      false
+    rescue Errno::ECHILD
+      true
+    end
+
+    def type(command)
+      @commands << command
+    end
+
+    def write_ruby(program)
+      @ruby_file = Tempfile.create(%w{irb- .rb})
+      @ruby_file.write(program)
+      @ruby_file.close
+    end
+
+    def integration_envs
+      {}
+    end
+  end
 end