# Mosh Tests ## ocb-aes This is a unit test for the OCB-AES encryption used in mosh, including Rogaway's OCB implementation and some of mosh's surrounding C++ support code. ## encrypt-decrypt This is a simple functional test of mosh's implementation of encrypted messages. ## base64 This tests Mosh's homegrown base64 functionality. The associated `genbase64.pl` script is used to independently generate validated test vectors. ## e2e-test This is a test framework for end-to-end testing of mosh. It uses tmux to invoke mosh in a nicely stable interactive pty, and also uses tmux's `capture-pane` command to get a dump of the terminal screen that mosh-client has drawn, neatly getting around Mosh's somewhat non-deterministic display redraw. There are four essential parts to the framework: * your test script * `e2e-test` * `e2e-test-server` * `e2e-test-subrs` The test script has two roles: when invoked without argments, it is a wrapper script for the overall test, and when invoked with an argument, it performs a testing-related action. In wrapper mode, it invokes e2e-test with action arguments, which are used to invoke the test script for actions at appropriate points by e2e-test. These provide a suite of behaviors that you can use to test various mosh behaviors. `e2e-test` is the heart of the framework. It runs actions as requested, logs their output, compares and/or validates their results, and generates the final result (exitstatus, mostly) for the Automake testing framework used by the mosh build. For test execution, it runs an action in an interactive session, in a tmux `screen`, to exercise some behavior. The action can optionally be run in a mosh session, or directly in tmux (doing both and comparing the result is a useful way to test complex terminal emulation behaviors). The action generally writes some output to the terminal that can later be verified by another action. Optionally, a client action can generate tty input or otherwise exercise mosh in some fashion (this capability is untested, but it's a useful place to use `expect` or other interactive simulations). The action is run by `e2e-test-server`, which is a relatively small wrapper script to capture errors, and capture the tmux screen. There are several different categories of actions: ### Execution `baseline` is an action that almost all tests will use. This invokes the test script inside mosh, where it can generate some output, and then captures the client-side tmux display with `tmux capture-pane`. `direct` is the same as the above, except that mosh is not used-- `e2e-wrapper-script` and the test script are invoked directly inside tmux. `variant` can be used to provide a slightly different action from `baseline`. ### Verification `verify` compares captures from the `baseline` and `direct` test actions, which are expected to be identical. `same` compares captures from the `baseline` and `variant` test actions, which are expected to be identical. `different` compares captures from the `baseline` and `variant` test actions, which are expected to be different. `post` is a catchall script hook which allows custom verification acions to be coded. ### Client wrappers `tmux` injects a wrapper command into the test command before tmux. If this is not run, a default command called `hold-stdin` is run instead. These commands are expected to hold tmux's stdin open, possibly injecting tmux commands, while the test runs. See `window-resize.test` for an example of this that manipulates tmux state. Alternately, this could use expect or something similar. `client` simply injects a wrapper command into the (long) test command between tmux and mosh. It's expected to interact with its wrapped command line as `expect` might do. This is not actually tested yet. ### Flags `mosh-args`, `client-args` and `server-args` inject extra arguments into the invocations of the respective commands. ## Logging and error reporting Each execution action is run, and recorded in `.test.d/.*`. `.exitstatus` is the exitstatus from the server wrapper. `.tmux.log` is the output of tmux for the entire test run for that action; `.capture` is a capture of the Mosh client screen after the test action is complete, generated with `tmux capture-pane`. In accordance with GNU Automake's test framework, the test should return these exit status values: * 0 test success * 1 test failure * 77 test skipped (tmux or ssh is unavailable if needed) * 99 hard error These values are also used internally between the various scripts; errors are conveyed out to the build test framework. ## Sample tests A few tests have been implemented so far to test the framework itself, and to provide examples for further development. `e2e-success` is a simple test that executes `baseline` and `direct` with the same stimulus (simply clearing the screen), and expects to see identical results. `e2e-failure` is similar to `e2e-success`, but expects to see different results from `baseline` and `variant`. Since it uses the same stimulus for the two execution action, it fails. A more realistic test might be to have `variant` execute some escape sequence that is absent from `baseline`; this would verify that the escape sequence actually does something. `emulation-back-tab` tests an escape sequence that mosh does not support. It expects the test to produce the output that would be generated if the escape sequence were implemented. If it gets output as expected when the escape sequence is *not* implemented, the test fails. But if the output does not match one of these two cases, the test returns an error. This is an example of error handling within the test framework. `unicode-later-combining` demonstrates mosh's handling of a Unicode edge case, a combining character drawn without a printing character in the same cell. It verifies the output in the `post` action; since there are a couple of different Unicode renderings that are reasonable in this case, a regex that covers both is used. It also implements an unused `variant` action that draws blank-space+combiner in a correct fashion. ## Notes The shell command `printf` is generally used in place of `echo` in this framework, because of its more precisely-specified and portable behavior. But beware, even `printf` varies between systems-- GNU printf, for example, implements `\e`, which is a non-POSIX extension unavailable in BSD implementations It's fairly simple to test each of these scripts independently, but the entire chain is a bit prone to behaving oddly in hard-to-debug ways. `set -x` is your friend here. The test scripts are a bit fragile about timeouts. They will generally run correctly on an unloaded machine without the `make -j` flag. Using `make -j` is obviously very convenient for development, and it works fine on faster machines, but I don't recommend it for automated testing.