ttytest2

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

A drop-in replacement for 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.

Minimum Requirements
Usage
Example for Canonical CLI or Shell
Example for Noncanonical CLI or Shell
Assertions
Output
Output Helpers
Troubleshooting
Constants
Tips
Docker
Contributing
License

Minimum Requirements

tmux >= 1.8
Ruby >= 3.2.3

Usage

More documentation available at ttytest2 docs.

There are more examples in the examples folder.

Example for Canonical CLI or 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.

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)

@tty.assert_contents_at(0, 0, '$ echo "Hello, world"')

@tty.assert_row_starts_with(0, '$ echo')
@tty.assert_row_ends_with(0, '"Hello, world"')
@tty.assert_row_starts_with(1, 'Hello')
@tty.assert_row_ends_with(1, ', world')

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

@tty.print # prints out the contents of the terminal

Example for Noncanonical CLI or 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.

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_newline # builtins for common outputs line newline

@tty.send_keys_one_at_a_time('ps')
@tty.assert_row_ends_with(1, 'ps')
@tty.send_keys(TTYtest:NEWLINE) # can use constants instead

@tty.assert_row_starts_with(2, ENV['USER'])
@tty.assert_row_ends_with(2, '$')
@tty.send_newline

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

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)
assert_contents_at(row_start, row_end, expected_text)

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)
send_home # simulate pressing the Home key
send_end # simulate pressing the End key
send_clear # clear the screen by sending clear ascii code

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.

# you can use @tty.rows to access the entire pane, split by line into an array.
p @tty.rows # prints out the contents of the terminal as a array.
@tty.print_rows # equivalent to above, just for ease of use.

# you can use @tty.capture to access the entire pane.
p "\n#{@tty.capture}" # prints out the contents of the terminal
@tty.print # equivalent to above, just for ease of use.

Constants

There are some commonly used keys available as constants to make interacting with your shell/CLI easy.

  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

Tips

If you are using ttyest2 to test your CLI, using sh is easier than bash because you don't have to worry about user, current working directory, etc. as shown in the examples above.

If you are using ttytest2 to test your shell, using assertions like assert_row_like, assert_row_starts_with, and assert_row_ends_with are going to be extremely helpful, especially if trying to test your shell in different environments or using a docker container.

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 ttytest2.

License

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