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Urchin is a test framework for shell. It is implemented in portable /bin/sh and should work on GNU/Linux, Mac OS X, and other Unix platforms.

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/scraperwiki/urchin.git

Run the tests

cd urchin
./urchin tests

The above command will run the tests in your systems default shell, /bin/sh (on recent Ubuntu this is dash, but it could be ksh or bash on other systems); to test urchin's cross-shell compatibility, run this:

cd urchin
./cross-shell-tests

Globally

Download Urchin like so (as root) (or use npm, below):

cd /usr/local/bin
wget https://raw.github.com/scraperwiki/urchin/master/urchin
chmod +x 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 run before everything else in the directory, including subdirectories. teardown_dir is run after everything else in the directory.

A directory's setup file, if it exists, is run right before each test file within the particular directory, and the teardown file is run 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.

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

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).
Note that if you alsow want your test scripts to work when run directly, outside of Urchin, be sure to target scripts that happen to be in the current directory with prefix ./; e.g., $TEST_SHELL ./baz (rather than $TEST_SHELL baz).

Then, on invocation of Urchin, prepend a definition of environment variable TEST_SHELL specifying the shell to test with, e.g.: TEST_SHELL=zsh urchin ./tests.
To test with multiple shells in sequence, use something like:

for shell in sh bash ksh zsh; do
  TEST_SHELL=$shell urchin ./tests
done

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.

(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.

To that end, 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

(c) Cross shell tests with urchin -x (experimental)

If you run urchin with the -sh flag, it will be as if you ran $TEST_SHELL. Unless $TEST_SHELL isn't set, in which case it'll be as if you ran /bin/sh. Putting this in she shebang line might eventually work out to be a cleaner way of doing cross-shell testing.

#!/usr/bin/env urchin -x
test a = a

Alternatives to Urchin

Alternatives to Urchin are discussed in this blog post.