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Urchin is a portable shell program that runs a directory of Unix-style programs and produces pretty output. It is normally used for testing shell programs, where each test case corresponds to a single file in the directory that Urchin runs.
Urchin is called "Urchin" because sea urchins have shells called "tests".
Try it out
Urchin's tests are written in Urchin, so you can run them to see what Urchin is like. Clone the repository
git clone git://github.com/tlevine/urchin.git
Run the tests
cd urchin
./urchin tests
Dependencies
Urchin depends on the following programs.
- sh
- echo
- printf
- mktemp
- readlink
- basename
- dirname
- sed
- grep
- cut
- true
- false
- which
- timeout
- sort
All of the above programs are usually included on base BSD installations. On GNU systems it should be sufficient to install the busybox package.
Urchin uses sort to format its output. GNU sort (as of GNU coreutils version 8.24) lacks the ability to sort in lexicographic order, and this feature is necessary for the output to look right. If your version of sort lacks this feature, Urchin will try to use one of the following tools for sorting.
- perl
- python
If no acceptable sorting program is available, Urchin will print a warning and use the incomplete sort that is installed on your system. This is not a big deal; if your test files all start with alphanumeric letters, the output should look fine.
Install
Urchin is contained in a single file, so you can install it by copying it to a
directory in your PATH. For example, you can run the following as root.
cd /usr/local/bin
wget https://raw.githubusercontent.com/tlevine/urchin/v0.0.6/urchin
chmod +x urchin
Urchin can be installed with npm too.
npm install -g urchin
Now you can run it.
urchin <test directory>
Run urchin -h to get command-line help.
Writing tests
Make a root directory for your tests. Inside it, put executable files that
exit 0 on success and something else on fail. Non-executable files and hidden
files (dotfiles) are ignored, so you can store fixtures right next to your
tests. Run urchin from inside the tests directory.
Urchin only cares about the exit status, so you can actually write your tests in any language, not just shell.
More about writing tests
Tests are organized recursively in directories, where the names of the files and directories have special meanings.
tests/
setup
setup_dir
bar/
setup
test_that_something_works
teardown
baz/
jack-in-the-box/
setup
test_that_something_works
teardown
cat-in-the-box/
fixtures/
thingy.pdf
test_thingy
teardown
Directories are processed in a depth-first order. When a particular directory
is processed, setup_dir is sourced before everything else in the directory,
including subdirectories. teardown_dir is sourced after everything else in
the directory.
A directory's setup file, if it exists, is sourced right before each test
file within the particular directory is run, and the teardown file is
sourced right after.
Files are only run if they are executable, and files beginning with . are
ignored. Thus, fixtures and libraries can be included sloppily within the test
directory tree. The test passes if the file exits 0; otherwise, it fails.
Tests files and subdirectories are run in ASCIIbetical order within each directory; that is, urchin looks for files within a directory in the following manner.
for file in *; do
do_something_with_test_file $file
done
Writing cross-shell compatibility tests for testing shell code
While you could write your test scripts to explicitly invoke the functionality to test with various shells, Urchin facilitates a more flexible approach.
The specific approach depends on your test scenario:
- (a) Your test scripts invoke scripts containing portable shell code.
- (b) Your scripts source scripts containing portable shell code.
(a) Cross-shell tests with test scripts that invoke shell scripts
Urchin sets the TEST_SHELL environment variable so that you may change the
shell with which your tests call other shell programs. To run your test
scripts in multiple shells you must call $TEST_SHELL in your tests and then
run urchin with the appropriate option.
In your test scripts, invoke the shell scripts to test via the shell
specified in environment variable TEST_SHELL rather than directly;
e.g.: $TEST_SHELL ../foo bar (rather than just ../foo bar).
Urchin runs tests in multiple different shells by default; Urchin has a list of default shells, and the following command will run your tests in all of those shells that Urchin detects.
./urchin ./tests
You can override the default list of shells with the -s flag.
urchin -s sh -s ksh ./tests
You can also
If TEST_SHELL has no value, Urchin defines it as /bin/sh, so the test
scripts can rely on $TEST_SHELL always containing a value when Urchin runs
them.
That said, we still recommand that you account for the possibility that
$TEST_SHELL does not contain a value so that you may run your test scripts
without Urchin. Supporting this case is very simple; when you invoke scripts
that happen to be in the current directory, be sure to use the prefix ./,
e.g., $TEST_SHELL ./baz rather than $TEST_SHELL baz.
(b) Cross-shell tests with test scripts that source shell scripts
If you source shell code in your test scripts, it is the test scripts themselves that must be run with the shell specified.
Urchin supports the -s <shell> option, which instructs
Urchin to invoke the test scripts with the specified shell; e.g., -s bash.
(In addition, Urchin sets environment variable TEST_SHELL to the specified
shell.)
Note that only test scripts that either have no shebang line at all or
have shebang line #!/bin/sh are invoked with the specified shell.
This allows non-shell test scripts or test scripts for specific
shells to coexist with those whose invocation should be controlled by -s.
To test with multiple shells in sequence, use something like:
for shell in sh bash ksh zsh; do
urchin -s $shell ./tests
done
References
On shell programming