[PATCH v2 0/8] Improvements for t/README

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

This is v2 of the t/README series. It should address the concerns
Junio and Jeff had about it.

Jeff:

  - Keep the ./ way of running tests, but elaborate a bit in the
    commit message

  - Mention --root's effects on the trash directory location

Junio:

  - The bit about ok/not ok moved out of the section on running
    tests.

  - Integrate a section that covers all the points in Junio's "Test
    your stuff" section, but does so as an itemized list, so it's
    easier to maintain it.

Other:

  - Made it diff --check friendly.

There's a diff against v1 of the series after this diffstat:

Ævar Arnfjörð Bjarmason (8):
  t/README: Tests are all +x, ./test, not sh ./test
  t/README: The trash is in 't/trash directory.$name'
  t/README: Typo: paralell -> parallel
  t/README: Document the prereq functions, and 3-arg test_*
  t/README: Document test_external*
  t/README: Document test_expect_code
  t/README: Add a section about skipping tests
  t/README: Document the do's and don'ts of tests

---

 t/README |  172 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 164 insertions(+), 8 deletions(-)

diff --git a/t/README b/t/README
index 29f795e..4a1cfc9 100644
--- a/t/README
+++ b/t/README
@@ -50,12 +50,6 @@ prove and other harnesses come with a lot of useful options. The
     # Repeat until no more failures
     $ prove -j 15 --state=failed,save ./t[0-9]*.sh
 
-The TAP support is completely incidental. A TAP harness is just a
-program that interprets the "ok"/"not ok" (and some other strings) in
-a special way. The only limitation this imposes is that you shouldn't
-echo "ok" or "not ok" by yourself at the beginning of a line, that'll
-confuse the TAP harness.
-
 You can also run each test individually from command line, like this:
 
     $ ./t3010-ls-files-killed-modified.sh
@@ -229,14 +223,92 @@ This test harness library does the following things:
 
  - Creates an empty test directory with an empty .git/objects database
    and chdir(2) into it.  This directory is 't/trash
-   directory.$test_name_without_dotsh' if you must know, but I do not
-   think you care.
+   directory.$test_name_without_dotsh', with t/ subject to change by
+   the --root option documented above.
 
  - Defines standard test helper functions for your scripts to
    use.  These functions are designed to make all scripts behave
    consistently when command line arguments --verbose (or -v),
    --debug (or -d), and --immediate (or -i) is given.
 
+Do's, don'ts & things to keep in mind
+-------------------------------------
+
+Here's a few examples of things you probably should and shouldn't do
+when writing tests.
+
+Do:
+
+ - Put as much code as possible inside test_expect_success and other
+   assertions.
+
+   Even code that isn't a test per se, but merely some setup code
+   should be inside a test assertion if at all possible. Test scripts
+   should only have trivial code outside of their assertions.
+
+ - Chain your test assertions
+
+   Write test code like this:
+
+	git merge foo &&
+	git push bar &&
+	test ...
+
+   Instead of:
+
+	git merge hla
+	git push gh
+	test ...
+
+   That way all of the commands in your tests will succeed or fail. If
+   you must ignore the return value of something (e.g. the return
+   value of export is unportable) it's best to indicate so explicitly
+   with a semicolon:
+
+	export HLAGH;
+	git merge hla &&
+	git push gh &&
+	test ...
+
+Don't:
+
+ - exit() within a <script> part.
+
+   The harness will catch this as a programming error of the test.
+   Use test_done instead if you need to stop the tests early (see
+   "Skipping tests" below).
+
+ - Break the TAP output
+
+   The raw output from your test might be interpreted by a TAP
+   harness. You usually don't have to worry about that. TAP harnesses
+   will ignore everything they don't know about, but don't step on
+   their toes in these areas:
+
+   - Don't print lines like "$x..$y" where $x and $y are integers.
+
+   - Don't print lines that begin with "ok" or "not ok".
+
+   A TAP harness expect a line that begins with either "ok" and "not
+   ok" to signal a test passed or failed (and our harness already
+   produces such lines), so your script shouldn't emit such lines to
+   their output.
+
+   You can gleam some further possible issues from the TAP grammar
+   (see http://search.cpan.org/perldoc?TAP::Parser::Grammar#TAP_Grammar)
+   but the best indication is to just run the tests with prove(1),
+   it'll complain if anything is amiss.
+
+Keep in mind:
+
+ - That what you print to stderr and stdout is usually ignored
+
+   Inside <script> part, the standard output and standard error
+   streams are discarded, and the test harness only reports "ok" or
+   "not ok" to the end user running the tests. Under --verbose, they
+   are shown to help debugging the tests.
+
+
 Skipping tests
 --------------