btrfs-progs: tests: add json formatter test coverage

Add a simple framework to exercise the json formatter and add testing
target that validates the output.

Run 'make test-json' to execute all available tests, requires 'jq'
utility for validation (https://github.com/stedolan/jq).

Signed-off-by: David Sterba <dsterba@suse.com>

.gitignore

@@ -47,6 +47,7 @@
 /ioctl-test
 /send-test
 /quick-test
+/json-formatter-test
 
 /aclocal.m4
 /autom4te.cache

Makefile

@@ -442,6 +442,17 @@ test-inst: all
 		$(MAKE) $(MAKEOPTS) DESTDIR=$$tmpdest install && \
 		$(RM) -rf -- $$tmpdest
 
+test-json: json-formatter-test
+	@echo "    [TEST]   json formatting"
+	@echo | jq
+	@{								\
+		max=`./json-formatter-test`;				\
+		for testno in `seq 1 $$max`; do				\
+			echo "    [TEST/json]  $$testno";		\
+			./json-formatter-test $$testno | jq >& /dev/null; \
+		done							\
+	}
+
 test: test-check test-check-lowmem test-mkfs test-misc test-cli test-convert test-fuzz
 
 testsuite: btrfs-corrupt-block btrfs-find-root btrfs-select-super fssum
@@ -679,6 +690,10 @@ hash-speedtest: crypto/hash-speedtest.c $(objects) $(libs_static)
 	@echo "    [LD]     $@"
 	$(Q)$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) $(LIBS)
 
+json-formatter-test: tests/json-formatter-test.c $(objects) $(libs_static)
+	@echo "    [LD]     $@"
+	$(Q)$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) $(LIBS)
+
 test-build: test-build-pre test-build-real
 
 test-build-pre:
@@ -731,7 +746,7 @@ clean: $(CLEANDIRS)
 		crypto/*.o crypto/*.o.d \
 	      ioctl-test quick-test library-test library-test-static \
               mktables btrfs.static mkfs.btrfs.static fssum \
-	      btrfs.box btrfs.box.static \
+	      btrfs.box btrfs.box.static json-formatter-test \
 	      $(check_defs) \
 	      $(libs) $(lib_links) \
 	      $(progs_static) \

tests/json-formatter-test.c

@@ -0,0 +1,96 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * 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, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+/*
+ * Test json output formatter
+ *
+ * Usage:
+ *
+ * $ ./json-formatter-test
+ * 123
+ *
+ * Without arguments returns the number of tests.
+ *
+ * $ ./json-formatter-test 17
+ * ...
+ *
+ * Run the given test, print formatted json for further processing or validation.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "common/utils.h"
+#include "common/format-output.h"
+#include "cmds/commands.h"
+
+/* Default empty output */
+void test_simple_empty()
+{
+	static const struct rowspec rows[] = {
+		ROWSPEC_END
+	};
+	struct format_ctx fctx;
+
+	fmt_start(&fctx, rows, 32, 0);
+	fmt_end(&fctx);
+}
+
+/* Single object with a few members */
+void test1()
+{
+	static const struct rowspec rows1[] = {
+		{ .key = "device", .fmt = "%s", .out_text = "device", .out_json = "device" },
+		{ .key = "devid", .fmt = "%llu", .out_text = "devid", .out_json = "devid" },
+		ROWSPEC_END
+	};
+	struct format_ctx fctx;
+
+	fmt_start(&fctx, rows1, 32, 0);
+	fmt_print_start_group(&fctx, "device-info", JSON_TYPE_MAP);
+	fmt_print(&fctx, "device", "/dev/sda");
+	fmt_print(&fctx, "devid", 1);
+	fmt_print_end_group(&fctx, NULL);
+	fmt_end(&fctx);
+}
+
+int main(int argc, char **argv)
+{
+	int testno;
+	static void (*tests[])() = {
+		test_simple_empty,
+		test1,
+	};
+
+	btrfs_config_init();
+	bconf.output_format = CMD_FORMAT_JSON;
+
+	/* Without arguments, print the number of tests available */
+	if (argc == 1) {
+		printf("%zu\n", ARRAY_SIZE(tests));
+		return 0;
+	}
+	testno = atoi(argv[1]);
+	testno--;
+
+	if (testno < 0 || testno >= ARRAY_SIZE(tests)) {
+		fprintf(stderr, "ERROR: test number %d is out of range (max %zu)\n",
+				testno + 1, ARRAY_SIZE(tests));
+		return 1;
+	}
+	tests[testno]();
+
+	return 0;
+}