Integrate contrib/file/tests with kyua/atf

This could be done better by making each test a separate ATF test case.
This exercise is left for the reader.

Reviewed by:	delphij (earlier version)
MFC after:	1 week
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D34303

etc/mtree/BSD.tests.dist

@@ -1010,6 +1010,8 @@
         ..
         file2c
         ..
+        file
+        ..
         find
         ..
         fold

usr.bin/file/Makefile

@@ -20,6 +20,8 @@
 #    ever read sources, credits must appear in the documentation.
 # 4. This notice may not be removed or altered.
 
+.include <src.opts.mk>
+
 SRCDIR=	${SRCTOP}/contrib/file
 .PATH: ${SRCDIR}/src
 .PATH: ${SRCDIR}/doc
@@ -38,6 +40,9 @@ FILEVER!= awk '$$1 == "\#define" && $$2 == "VERSION" { print $$3; exit }' \
 
 CLEANFILES+=	${MAN}
 
+HAS_TESTS=
+SUBDIR.${MK_TESTS}+= tests
+
 .include <bsd.prog.mk>
 
 .for mp in ${MAN}

usr.bin/file/tests/Makefile

@@ -0,0 +1,8 @@
+PACKAGE=	tests
+ATF_TESTS_SH=	file_test
+
+SRCDIR=		${SRCTOP}/contrib/file/tests
+_files!=	echo ${SRCDIR}/*.testfile ${SRCDIR}/*.result ${SRCDIR}/*.magic
+${PACKAGE}FILES+=${_files}
+
+.include <bsd.test.mk>

usr.bin/file/tests/file_test.sh

@@ -0,0 +1,54 @@
+#!/usr/libexec/atf-sh
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# Copyright (c) 2022 Eric van Gyzen
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+atf_test_case contrib_file_tests cleanup
+contrib_file_tests_body() {
+	srcdir="$(atf_get_srcdir)"
+
+	for testfile in "${srcdir}"/*.testfile; do
+		test_name="${testfile%.testfile}"
+		result_file="${test_name}.result"
+		magic_file="${test_name}.magic"
+		file_args=
+		if [ -e "${magic_file}" ]; then
+			file_args="${file_args} --magic-file ${magic_file}"
+		fi
+		# The result files were created in UTC.
+		TZ=Z atf_check -o save:actual_output file ${file_args} \
+		    --brief "$testfile"
+		atf_check -o save:trimmed_output tr -d '\012' < actual_output
+		atf_check cmp trimmed_output "$result_file"
+	done
+}
+
+contrib_file_tests_cleanup() {
+	rm -f actual_output trimmed_output
+}
+
+atf_init_test_cases() {
+	atf_add_test_case contrib_file_tests
+}