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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. Download the stable version like so.
wget -o urchin.tar.gz http://tlevine.sdf.org/urchin/tarball/urchin.tar.gz?tag=v0.1.0 tar xzf urchin.tar.gz
Run the tests
cd urchin ./urchin tests
You can clone the unstable version from fossil.
fossil clone http://tlevine.sdf.org/urchin/ urchin.fossil
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 http://tlevine.sdf.org/urchin/doc/v0.1.0/urchin chmod +x urchin
Now you can run it.
urchin <test directory>
urchin -h to get command-line help.
Make a root directory for your tests. Inside it, put executable files that
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.
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;
$TEST_SHELL ../foo bar (rather than just
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.
You can override the default list of shells with the
urchin -s sh -s ksh ./tests
You can also
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
That said, we still recommend 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
$TEST_SHELL ./baz rather than
(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.,
(In addition, Urchin sets environment variable
TEST_SHELL to the specified
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 other languages
or for specific shells to coexist with those whose invocation should be