Method: MiniTest::Assertions#capture_io

Defined in:

lib/minitest/unit.rb

#capture_io ⇒ Object

Captures $stdout and $stderr into strings:

out, err = capture_io do
  puts "Some info"
  warn "You did a bad thing"
end

assert_match %r%info%, out
assert_match %r%bad%, err

NOTE: For efficiency, this method uses StringIO and does not capture IO for subprocesses. Use #capture_subprocess_io for that.

# File 'lib/minitest/unit.rb', line 469

def capture_io
  require 'stringio'

  captured_stdout, captured_stderr = StringIO.new, StringIO.new

  synchronize do
    orig_stdout, orig_stderr = $stdout, $stderr
    $stdout, $stderr         = captured_stdout, captured_stderr

    begin
      yield
    ensure
      $stdout = orig_stdout
      $stderr = orig_stderr
    end
  end

  return captured_stdout.string, captured_stderr.string
end