ScriptTest

Status & License

ScriptTest is an extraction of paste.fixture.TestFileEnvironment from the Paste project. It was originally written to test Paste Script.

It is licensed under an MIT-style permissive license.

Discussion should happen on the Paste mailing list, and bugs should go in the Paste bug tracker.

It is available in an hg repository. You can get a checkout with:

$ hg clone http://bitbucket.org/ianb/scripttest/

Purpose & Introduction

This library helps you test command-line scripts. It runs a script and watches the output, looks for non-zero exit codes, output on stderr, and any files created, deleted, or modified.

To start you instantiate TestFileEnvironment, which is the context in which all your scripts are run. You give it a base directory (typically a scratch directory), or if you don’t it will guess call_module_dir/test-output/. Example:

>>> from scripttest import TestFileEnvironment
>>> env = TestFileEnvironment('./test-output')

Note

Everything in ./test-output will be deleted every test run. To make sure you don’t point at an important directory, the scratch directory must be created by ScriptTest (a hidden file is written by ScriptTest to confirm that it created the directory). If the directory already exists, you must delete it manually.

Then you run scripts with env.run(script, arg1, arg2, ...):

>>> print(env.run('echo', 'hey'))
Script result: echo hey
-- stdout: --------------------
hey
<BLANKLINE>

There’s several keyword arguments you can use with env.run():

expect_error: (default False)
Don’t raise an exception in case of errors
expect_stderr: (default expect_error)
Don’t raise an exception if anything is printed to stderr
stdin: (default "")
Input to the script
cwd: (default self.cwd)
The working directory to run in (default base_dir)

As you can see from the options, if the script indicates anything error-like it is, by default, turned into an exception. This of course includes a non-zero response code. Also any output on stderr also counts as an error (unless turned off with expect_stderr=True).

The object you get back from a run represents what happened during the script. It has a useful str() (as you can see in the previous example) that shows a summary and can be useful in a doctest. It also has several useful attributes:

stdout, stderr:
What is produced on those streams
returncode:
The return code of the script.
files_created, files_deleted, files_updated:
Dictionaries mapping filenames (relative to the base_dir) to FoundFile or FoundDir objects.

Of course by default stderr must be empty, and returncode must be zero, since anything else would be considered an error.

Of particular interest are the dictionaries files_created, etc. These show just what files were handled by the script. Each dictionary points to another helper object for inspecting the files (.files_deleted contains the files as they existed before the script ran).

Each file or directory object has useful attributes:

path:
The path of the file, relative to the base_path
full:
The full path
stat:
The results of os.stat. Also mtime and size contain the .st_mtime and st_size of the stat. (Directories have no size)
bytes:
The contents of the file (does not apply to directories).
file, dir:
file is true for files, dir is true for directories.

You may use the in operator with the file objects (tested against the contents of the file), and the .mustcontain() method, where file.mustcontain('a', 'b') means assert 'a' in file; assert 'b' in file.

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