tests: refactor --write-junit-xml code

The code writing JUnit XML is interspersed directly with all the code in
`t/test-lib.sh`, and it is therefore not only ill-separated, but
introducing yet another output format would make the situation even
worse.

Let's introduce an abstraction layer by hiding the JUnit XML code behind
four new functions that are supposed to be called before and after each
test and test case.

This is not just an academic exercise, refactoring for refactoring's
sake. We _actually_ want to introduce such a new output format, to
make it substantially easier to diagnose test failures in our GitHub
workflow, therefore we do need this refactoring.

This commit is best viewed with `git show --color-moved
--color-moved-ws=allow-indentation-change <commit>`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/t/test-lib-junit.sh b/t/test-lib-junit.sh
new file mode 100644
index 0000000000..9d55d74d76
--- /dev/null
+++ b/t/test-lib-junit.sh
@@ -0,0 +1,126 @@
+# Library of functions to format test scripts' output in JUnit XML
+# format, to support Git's test suite result to be presented in an
+# easily digestible way on Azure Pipelines.
+#
+# Copyright (c) 2022 Johannes Schindelin
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see http://www.gnu.org/licenses/ .
+#
+# The idea is for `test-lib.sh` to source this file when the user asks
+# for JUnit XML; these functions will then override (empty) functions
+# that are are called at the appropriate times during the test runs.
+
+start_test_output () {
+	junit_xml_dir="$TEST_OUTPUT_DIRECTORY/out"
+	mkdir -p "$junit_xml_dir"
+	junit_xml_base=${1##*/}
+	junit_xml_path="$junit_xml_dir/TEST-${junit_xml_base%.sh}.xml"
+	junit_attrs="name=\"${junit_xml_base%.sh}\""
+	junit_attrs="$junit_attrs timestamp=\"$(TZ=UTC \
+		date +%Y-%m-%dT%H:%M:%S)\""
+	write_junit_xml --truncate "<testsuites>" "  <testsuite $junit_attrs>"
+	junit_suite_start=$(test-tool date getnanos)
+	if test -n "$GIT_TEST_TEE_OUTPUT_FILE"
+	then
+		GIT_TEST_TEE_OFFSET=0
+	fi
+}
+
+start_test_case_output () {
+	junit_start=$(test-tool date getnanos)
+}
+
+finalize_test_case_output () {
+	test_case_result=$1
+	shift
+	case "$test_case_result" in
+	ok)
+		set "$*"
+		;;
+	failure)
+		junit_insert="<failure message=\"not ok $test_count -"
+		junit_insert="$junit_insert $(xml_attr_encode "$1")\">"
+		junit_insert="$junit_insert $(xml_attr_encode \
+			"$(if test -n "$GIT_TEST_TEE_OUTPUT_FILE"
+			   then
+				test-tool path-utils skip-n-bytes \
+					"$GIT_TEST_TEE_OUTPUT_FILE" $GIT_TEST_TEE_OFFSET
+			   else
+				printf '%s\n' "$@" | sed 1d
+			   fi)")"
+		junit_insert="$junit_insert</failure>"
+		if test -n "$GIT_TEST_TEE_OUTPUT_FILE"
+		then
+			junit_insert="$junit_insert<system-err>$(xml_attr_encode \
+				"$(cat "$GIT_TEST_TEE_OUTPUT_FILE")")</system-err>"
+		fi
+		set "$1" "      $junit_insert"
+		;;
+	fixed)
+		set "$* (breakage fixed)"
+		;;
+	broken)
+		set "$* (known breakage)"
+		;;
+	skip)
+		message="$(xml_attr_encode "$skipped_reason")"
+		set "$1" "      <skipped message=\"$message\" />"
+		;;
+	esac
+
+	junit_attrs="name=\"$(xml_attr_encode "$this_test.$test_count $1")\""
+	shift
+	junit_attrs="$junit_attrs classname=\"$this_test\""
+	junit_attrs="$junit_attrs time=\"$(test-tool \
+		date getnanos $junit_start)\""
+	write_junit_xml "$(printf '%s\n' \
+		"    <testcase $junit_attrs>" "$@" "    </testcase>")"
+	junit_have_testcase=t
+}
+
+finalize_test_output () {
+	if test -n "$junit_xml_path"
+	then
+		test -n "$junit_have_testcase" || {
+			junit_start=$(test-tool date getnanos)
+			write_junit_xml_testcase "all tests skipped"
+		}
+
+		# adjust the overall time
+		junit_time=$(test-tool date getnanos $junit_suite_start)
+		sed -e "s/\(<testsuite.*\) time=\"[^\"]*\"/\1/" \
+			-e "s/<testsuite [^>]*/& time=\"$junit_time\"/" \
+			-e '/^ *<\/testsuite/d' \
+			<"$junit_xml_path" >"$junit_xml_path.new"
+		mv "$junit_xml_path.new" "$junit_xml_path"
+
+		write_junit_xml "  </testsuite>" "</testsuites>"
+		write_junit_xml=
+	fi
+}
+
+write_junit_xml () {
+	case "$1" in
+	--truncate)
+		>"$junit_xml_path"
+		junit_have_testcase=
+		shift
+		;;
+	esac
+	printf '%s\n' "$@" >>"$junit_xml_path"
+}
+
+xml_attr_encode () {
+	printf '%s\n' "$@" | test-tool xml-encode
+}