test-lib: extract Bash version check for '-x' tracing

One of our test scripts, 't1510-repo-setup.sh' [1], still can't be
reliably run with '-x' tracing enabled, unless it's executed with a
Bash version supporting BASH_XTRACEFD (since v4.1).  We have a lengthy
condition to check the version of the shell running the test script,
and disable tracing if it's not executed with a suitable Bash version
[2].

Move this check out from the option parsing loop, so other options can
imply '-x' by setting 'trace=t', without missing this Bash version
check.

[1] 5827506928 (t1510-repo-setup: mark as untraceable with '-x',
    2018-02-24)
[2] 5fc98e79fc (t: add means to disable '-x' tracing for individual
    test scripts, 2018-02-24)

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

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 4c3744cce4fc99e482a4d07da40188ccc68b6a97..1f02e2e25b9e09e61cbed88279c883a64a206da3 100644 (file)
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -317,24 +317,7 @@ do
                GIT_TEST_CHAIN_LINT=0
                shift ;;
        -x)
-               # Some test scripts can't be reliably traced  with '-x',
-               # unless the test is run with a Bash version supporting
-               # BASH_XTRACEFD (introduced in Bash v4.1).  Check whether
-               # this test is marked as such, and ignore '-x' if it
-               # isn't executed with a suitable Bash version.
-               if test -z "$test_untraceable" || {
-                    test -n "$BASH_VERSION" && eval '
-                      test ${BASH_VERSINFO[0]} -gt 4 || {
-                        test ${BASH_VERSINFO[0]} -eq 4 &&
-                        test ${BASH_VERSINFO[1]} -ge 1
-                      }
-                    '
-                  }
-               then
-                       trace=t
-               else
-                       echo >&2 "warning: ignoring -x; '$0' is untraceable without BASH_XTRACEFD"
-               fi
+               trace=t
                shift ;;
        -V|--verbose-log)
                verbose_log=t
@@ -353,6 +336,24 @@ then
        test -z "$verbose_log" && verbose=t
 fi
 
+if test -n "$trace" && test -n "$test_untraceable"
+then
+       # '-x' tracing requested, but this test script can't be reliably
+       # traced, unless it is run with a Bash version supporting
+       # BASH_XTRACEFD (introduced in Bash v4.1).
+       if test -n "$BASH_VERSION" && eval '
+            test ${BASH_VERSINFO[0]} -gt 4 || {
+              test ${BASH_VERSINFO[0]} -eq 4 &&
+              test ${BASH_VERSINFO[1]} -ge 1
+            }
+          '
+       then
+               : Executed by a Bash version supporting BASH_XTRACEFD.  Good.
+       else
+               echo >&2 "warning: ignoring -x; '$0' is untraceable without BASH_XTRACEFD"
+               trace=
+       fi
+fi
 if test -n "$trace" && test -z "$verbose_log"
 then
        verbose=t