t/README: Document the do's and don'ts of tests
Add a "Do's, don'ts & things to keep in mind" subsection to the "Writing Tests" documentation. Much of this is based on Junio C Hamano's "Test your stuff" section in <7vhbkj2kcr.fsf@alter.siamese.dyndns.org>. I turned it into a list of do's and don'ts to make it easier to skim it, and integrated my note that a TAP harness will get confused if you print "ok" or "not ok" at the beginning of a line. Thad had to be fixed in 335f87871fe5aa6b3fd55b2b4e80f16fe9681483 when TAP support was introduced. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ævar Arnfjörð Bjarmason committed
Jul 2, 2010 at 14:59 UTC
20873f45e7fe23a8530e643d2eea9566d57f2fd4
1 file changed
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t/README
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@@ -231,6 +231,84 @@ This test harness library does the following things:
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consistently when command line arguments --verbose (or -v),
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--debug (or -d), and --immediate (or -i) is given.
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+Do's, don'ts & things to keep in mind
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+-------------------------------------
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+
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+Here's a few examples of things you probably should and shouldn't do
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+when writing tests.
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+
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+Do:
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+
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+ - Put as much code as possible inside test_expect_success and other
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+ assertions.
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+
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+ Even code that isn't a test per se, but merely some setup code
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+ should be inside a test assertion if at all possible. Test scripts
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+ should only have trivial code outside of their assertions.
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+
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+ - Chain your test assertions
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+
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+ Write test code like this:
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+
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+ git merge foo &&
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+ git push bar &&
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+ test ...
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+
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+ Instead of:
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+
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+ git merge hla
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+ git push gh
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+ test ...
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+
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+ That way all of the commands in your tests will succeed or fail. If
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+ you must ignore the return value of something (e.g. the return
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+ value of export is unportable) it's best to indicate so explicitly
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+ with a semicolon:
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+
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+ export HLAGH;
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+ git merge hla &&
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+ git push gh &&
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+ test ...
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+
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+Don't:
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+
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+ - exit() within a <script> part.
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+
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+ The harness will catch this as a programming error of the test.
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+ Use test_done instead if you need to stop the tests early (see
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+ "Skipping tests" below).
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+
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+ - Break the TAP output
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+
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+ The raw output from your test might be interpreted by a TAP
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+ harness. You usually don't have to worry about that. TAP harnesses
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+ will ignore everything they don't know about, but don't step on
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+ their toes in these areas:
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+
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+ - Don't print lines like "$x..$y" where $x and $y are integers.
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+
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+ - Don't print lines that begin with "ok" or "not ok".
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+
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+ A TAP harness expect a line that begins with either "ok" and "not
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+ ok" to signal a test passed or failed (and our harness already
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+ produces such lines), so your script shouldn't emit such lines to
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+ their output.
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+
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+ You can glean some further possible issues from the TAP grammar
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+ (see http://search.cpan.org/perldoc?TAP::Parser::Grammar#TAP_Grammar)
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+ but the best indication is to just run the tests with prove(1),
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+ it'll complain if anything is amiss.
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+
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+Keep in mind:
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+
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+ - That what you print to stderr and stdout is usually ignored
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+
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+ Inside <script> part, the standard output and standard error
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+ streams are discarded, and the test harness only reports "ok" or
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+ "not ok" to the end user running the tests. Under --verbose, they
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+ are shown to help debugging the tests.
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+
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+
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Skipping tests
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--------------
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