ttytest2

ttytest2 is an acceptance test framework for interactive console applications. It's like capybara for the terminal.

A drop-in replacement for https://github.com/jhawthorn/ttytest, because I had some features I needed for my own project.

It works by running commands inside a tmux session, capturing the pane, and comparing the content. The assertions will wait a specified amount of time (default 2 seconds) for the expected content to appear.

Gem Version

Minimum Requirements

  • tmux >= 1.8
  • Ruby >= 3.2.3

Usage

More documentation available at [(https://www.rubydoc.info/gems/ttytest2)].

Assertions

The main way to use TTYtest is through assertions. When called on a TTYtest::Terminal, each of these will be retried (for up to 2 seconds).

Available assertions:

  • assert_row(row_number, expected_text)
  • assert_row_at(row_number, column_start_position, column_end_position, expected_text)
  • assert_row_like(row_number, expected_text)
  • assert_row_starts_with(row_number, expected_text)
  • assert_row_ends_with(row_number, expected_text)
  • assert_cursor_position(x: x, y: y)
  • assert_cursor_visible
  • assert_cursor_hidden
  • assert_contents(lines_of_terminal)

Sending Output

You can send output to the terminal with the following calls.

  • send_keys(output) # for canonical shells/CLI's (or multi-character keys for noncanonical shells/CLI's)
  • send_keys_one_at_a_time(output) # for noncanonical shells/CLI's
  • send_keys_exact(output) # for sending tmux specific keys (DC for delete, Escape for ESC, etc.)

Output Helpers

Helper functions to make sending output easier! They use the methods above under 'Sending Output' section under the hood.

  • send_newline # equivalent to @tty.send_keys(%(\n))
  • send_newlines(number_of_times) # equivalent to calling send_newline number_of_times
  • send_backspace # equivalent to @tty.send_keys(TTYtest::BACKSPACE)
  • send_backspaces(number_of_times) # equivalent to calling send_backspace number_of_times
  • send_delete # equivalent to calling send_keys_exact(%(DC))
  • send_deletes # equivalent to calling send_delete number_of_times
  • send_right_arrow
  • send_right_arrows(number_of_times)
  • send_left_arrow
  • send_left_arrows(number_of_times)
  • send_up_arrow
  • send_up_arrows(number_of_times)
  • send_down_arrow
  • send_down_arrows(number_of_times)

Troubleshooting

You can use the method rows to get all rows of the terminal as an array, of use the method capture to get the contents of the terminal window. This can be useful when troubleshooting.

p @tty.rows # prints out the contents of the terminal as a array => ["$ echo \"Hello, world\"", "Hello, world", "$", "", "", "", ...]
puts "\n#{@tty.capture}" # prints out the contents of the terminal

Example Canonical CLI/Shell

Most people should use send_keys, if you are writing or working with a noncanonical shell/CLI, you will probably know it! Most shell/CLI applications are canonical.

There are more examples in the examples folder.

require 'ttytest'

@tty = TTYtest.new_terminal(%{PS1='$ ' /bin/sh}, width: 80, height: 24)
@tty.assert_row(0, '$')
@tty.assert_cursor_position(x: 2, y: 0)

@tty.send_keys(%{echo "Hello, world"\n})

@tty.assert_contents <<TTY
$ echo "Hello, world"
Hello, world
$
TTY
@tty.assert_cursor_position(x: 2, y: 2)

p @tty.rows # => ["$ echo \"Hello, world\"", "Hello, world", "$", "", "", "", ...]

puts "\n#{@tty.capture}" # prints out the contents of the terminal

Example Noncanonical CLI/Shell

If you are working with a noncanonical shell, you need to use send_keys_one_at_a_time to have your shell/CLI process the input correctly.

Also useful if you need to send input one character at a time for whatever reason.

'Multi-character' characters like '\n' need to be sent with send-keys, though.

There are more examples in the examples folder.

require 'ttytest'

@tty = TTYtest.new_terminal(%{PS1='$ ' /bin/noncanonical-sh}, width: 80, height: 24)
@tty.assert_row_starts_with(0, ENV['USER'])
@tty.assert_row_ends_with(0, '$')

@tty.send_keys_one_at_a_time('ls')
@tty.assert_row_ends_with(0, 'ls')
@tty.send_keys(%(\n)) # make sure to use send_keys for 'multi-character' characters like \n, \r, \t, etc.

@tty.send_keys_one_at_a_time('ps')
@tty.assert_row_ends_with(0, 'ps')
@tty.send_keys(TTYtest:NEWLINE) # can use constants instead

@tty.assert_row_starts_with(0, ENV['USER'])
@tty.assert_row_ends_with(0, '$')
@tty.send_newline # an alternative to the 2 above methods to send \n to the terminal

puts "\n#{@tty.capture}" # prints out the contents of the terminal

Constants

There are some commonly used keys available as constants to make interacting with your shell/CLI easy. Most of them are self-evident, BACKSPACE is the same as hitting the backspace key on the keyboard.

  TTYtest::BACKSPACE
  TTYtest::TAB
  TTYtest::CTRLF
  TTYtest::CTRLC
  TTYtest::CTRLD
  TTYtest::ESCAPE

  TTYtest::UP_ARROW
  TTYtest::DOWN_ARROW
  TTYtest::RIGHT_ARROW
  TTYtest::LEFT_ARROW

  TTYtest::CLEAR # clear the screen

Docker

Easy to use from Docker. Add this to your dockerfile to get started.

RUN apt update && \
  apt install gcc make ruby tmux -y && \
  gem install ttytest2

# add this if you have issues
# ENV RUBYOPT="-KU -E utf-8:utf-8"

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/a-eski/ttytest2.

License

The gem is available as open source under the terms of the MIT License.