tests: add 'test_bool_env' to catch non-bool GIT_TEST_* values

Since 3b072c577b (tests: replace test_tristate with "git env--helper",
2019-06-21) we get the normalized bool values of various GIT_TEST_*
environment variables via 'git env--helper'.  Now, while the 'git
env--helper' command itself does catch invalid values in the
environment variable or in the given --default and exits with error
(exit code 128 or 129, respectively), it's invoked in conditions like
'if ! git env--helper ...', which means that all invalid bool values
are interpreted the same as the ordinary 'false' (exit code 1).  This
has led to inadvertently skipped httpd tests in our CI builds for a
couple of weeks, see 3960290675 (ci: restore running httpd tests,
2019-09-06).

Let's be more careful about what the test suite accepts as bool values
in GIT_TEST_* environment variables, and error out loud and clear on
invalid values instead of simply skipping tests.  Add the
'test_bool_env' helper function to encapsulate the invocation of 'git
env--helper' and the verification of its exit code, and replace all
invocations of that command in our test framework and test suite with
a call to this new helper (except in 't0017-env-helper.sh', of
course).

  $ GIT_TEST_GIT_DAEMON=YesPlease ./t5570-git-daemon.sh
  fatal: bad numeric config value 'YesPlease' for 'GIT_TEST_GIT_DAEMON': invalid unit
  error: test_bool_env requires bool values both for $GIT_TEST_GIT_DAEMON and for the default fallback

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 4d3f7ba295..03b208b126 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -916,6 +916,40 @@ test_expect_success 'test_oid can look up data for SHA-256' '
 	test "$hexsz" -eq 64
 '
 
+test_expect_success 'test_bool_env' '
+	(
+		sane_unset envvar &&
+
+		test_bool_env envvar true &&
+		! test_bool_env envvar false &&
+
+		envvar= &&
+		export envvar &&
+		! test_bool_env envvar true &&
+		! test_bool_env envvar false &&
+
+		envvar=true &&
+		test_bool_env envvar true &&
+		test_bool_env envvar false &&
+
+		envvar=false &&
+		! test_bool_env envvar true &&
+		! test_bool_env envvar false &&
+
+		envvar=invalid &&
+		# When encountering an invalid bool value, test_bool_env
+		# prints its error message to the original stderr of the
+		# test script, hence the redirection of fd 7, and aborts
+		# with "exit 1", hence the subshell.
+		! ( test_bool_env envvar true ) 7>err &&
+		grep "error: test_bool_env requires bool values" err &&
+
+		envvar=true &&
+		! ( test_bool_env envvar invalid ) 7>err &&
+		grep "error: test_bool_env requires bool values" err
+	)
+'
+
 ################################################################
 # Basics of the basics