Merge branch 'fs/test-prereq'

The test framework learns to list unsatisfied test prerequisites,
and optionally error out when prerequisites that are expected to be
satisfied are not.

* fs/test-prereq:
  test-lib: make BAIL_OUT() work in tests and prereq
  test-lib: introduce required prereq for test runs
  test-lib: show missing prereq summary

t/README

@@ -466,6 +466,12 @@ explicitly providing repositories when accessing submodule objects is
 complete or needs to be abandoned for whatever reason (in which case the
 migrated codepaths still retain their performance benefits).
 
+GIT_TEST_REQUIRE_PREREQ=<list> allows specifying a space speparated list of
+prereqs that are required to succeed. If a prereq in this list is triggered by
+a test and then fails then the whole test run will abort. This can help to make
+sure the expected tests are executed and not silently skipped when their
+dependency breaks or is simply not present in a new environment.
+
 Naming Tests
 ------------
 

t/aggregate-results.sh

@@ -6,6 +6,7 @@ success=0
 failed=0
 broken=0
 total=0
+missing_prereq=
 
 while read file
 do
@@ -30,10 +31,26 @@ do
 			broken=$(($broken + $value)) ;;
 		total)
 			total=$(($total + $value)) ;;
+		missing_prereq)
+			missing_prereq="$missing_prereq,$value" ;;
 		esac
 	done <"$file"
 done
 
+if test -n "$missing_prereq"
+then
+	unique_missing_prereq=$(
+		echo $missing_prereq |
+		tr -s "," "\n" |
+		grep -v '^$' |
+		sort -u |
+		paste -s -d ' ')
+	if test -n "$unique_missing_prereq"
+	then
+		printf "\nmissing prereq: $unique_missing_prereq\n\n"
+	fi
+fi
+
 if test -n "$failed_tests"
 then
 	printf "\nfailed test(s):$failed_tests\n\n"

t/test-lib-functions.sh

@@ -680,6 +680,17 @@ test_have_prereq () {
 			# Keep a list of missing prerequisites; restore
 			# the negative marker if necessary.
 			prerequisite=${negative_prereq:+!}$prerequisite
+
+			# Abort if this prereq was marked as required
+			if test -n "$GIT_TEST_REQUIRE_PREREQ"
+			then
+				case " $GIT_TEST_REQUIRE_PREREQ " in
+				*" $prerequisite "*)
+					BAIL_OUT "required prereq $prerequisite failed"
+					;;
+				esac
+			fi
+
 			if test -z "$missing_prereq"
 			then
 				missing_prereq=$prerequisite

t/test-lib.sh

@@ -589,6 +589,15 @@ USER_TERM="$TERM"
 TERM=dumb
 export TERM USER_TERM
 
+# What is written by tests to stdout and stderr is sent to different places
+# depending on the test mode (e.g. /dev/null in non-verbose mode, piped to tee
+# with --tee option, etc.). We save the original stdin to FD #6 and stdout and
+# stderr to #5 and #7, so that the test framework can use them (e.g. for
+# printing errors within the test framework) independently of the test mode.
+exec 5>&1
+exec 6<&0
+exec 7>&2
+
 _error_exit () {
 	finalize_junit_xml
 	GIT_EXIT_OK=t
@@ -612,7 +621,7 @@ BAIL_OUT () {
 	local bail_out="Bail out! "
 	local message="$1"
 
-	say_color error $bail_out "$message"
+	say_color >&5 error $bail_out "$message"
 	_error_exit
 }
 
@@ -637,9 +646,6 @@ then
 	exit 0
 fi
 
-exec 5>&1
-exec 6<&0
-exec 7>&2
 if test "$verbose_log" = "t"
 then
 	exec 3>>"$GIT_TEST_TEE_OUTPUT_FILE" 4>&3
@@ -669,6 +675,8 @@ test_fixed=0
 test_broken=0
 test_success=0
 
+test_missing_prereq=
+
 test_external_has_tap=0
 
 die () {
@@ -1069,6 +1077,14 @@ test_skip () {
 			of_prereq=" of $test_prereq"
 		fi
 		skipped_reason="missing $missing_prereq${of_prereq}"
+
+		# Keep a list of all the missing prereq for result aggregation
+		if test -z "$missing_prereq"
+		then
+			test_missing_prereq=$missing_prereq
+		else
+			test_missing_prereq="$test_missing_prereq,$missing_prereq"
+		fi
 	fi
 
 	case "$to_skip" in
@@ -1175,6 +1191,7 @@ test_done () {
 		fixed $test_fixed
 		broken $test_broken
 		failed $test_failure
+		missing_prereq $test_missing_prereq
 
 		EOF
 	fi