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[PATCH v6 2/3] unit tests: add TAP unit test framework

From
Josh Steadmon <steadmon@google.com>
Date
Aug 16, 2023, 23:50 UTC
Message-ID
<ca284c575ece0aee7149641d5fb1977ccd7e7873.1692229626.git.steadmon@google.com>
In-Reply-To
<cover.1692229626.git.steadmon@google.com>
From: Phillip Wood <phillip.wood@dunelm.org.uk>

This patch contains an implementation for writing unit tests with TAP output. Each test is a function that contains one or more checks. The test is run with the TEST() macro and if any of the checks fail then the test will fail. A complete program that tests STRBUF_INIT would look like

     #include "test-lib.h"
     #include "strbuf.h"
     static void t_static_init(void)
     {
             struct strbuf buf = STRBUF_INIT;
             check_uint(buf.len, ==, 0);
             check_uint(buf.alloc, ==, 0);
             if (check(buf.buf == strbuf_slopbuf))
		    return; /* avoid SIGSEV */
             check_char(buf.buf[0], ==, '\0');
     }
     int main(void)
     {
             TEST(t_static_init(), "static initialization works);
             return test_done();
     }
The output of this program would be
     ok 1 - static initialization works
     1..1

If any of the checks in a test fail then they print a diagnostic message to aid debugging and the test will be reported as failing. For example a failing integer check would look like

     # check "x >= 3" failed at my-test.c:102
     #    left: 2
     #   right: 3
     not ok 1 - x is greater than or equal to three

There are a number of check functions implemented so far. check() checks a boolean condition, check_int(), check_uint() and check_char() take two values to compare and a comparison operator. check_str() will check if two strings are equal. Custom checks are simple to implement as shown in the comments above test_assert() in test-lib.h.

Tests can be skipped with test_skip() which can be supplied with a reason for skipping which it will print. Tests can print diagnostic messages with test_msg(). Checks that are known to fail can be wrapped in TEST_TODO().

There are a couple of example test programs included in this patch. t-basic.c implements some self-tests and demonstrates the diagnostic output for failing test. The output of this program is checked by t0080-unit-test-output.sh. t-strbuf.c shows some example unit tests for strbuf.c

The unit tests can be built with "make unit-tests" (this works but the Makefile changes need some further work). Once they have been built they can be run manually (e.g t/unit-tests/t-strbuf) or with prove.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Josh Steadmon <steadmon@google.com>
diff --git a/Makefile b/Makefile
index e440728c24..4016da6e39 100644

--- a/Makefile
+++ b/Makefile
@@ -682,6 +682,8 @@ TEST_BUILTINS_OBJS =
 TEST_OBJS =
 TEST_PROGRAMS_NEED_X =
 THIRD_PARTY_SOURCES =
+UNIT_TEST_PROGRAMS =
+UNIT_TEST_DIR = t/unit-tests

 # Having this variable in your environment would break pipelines because
 # you cause "cd" to echo its destination to stdout.  It can also take
@@ -1331,6 +1333,12 @@ THIRD_PARTY_SOURCES += compat/regex/%
 THIRD_PARTY_SOURCES += sha1collisiondetection/%
 THIRD_PARTY_SOURCES += sha1dc/%

+UNIT_TEST_PROGRAMS += t-basic
+UNIT_TEST_PROGRAMS += t-strbuf
+UNIT_TEST_PROGS = $(patsubst %,$(UNIT_TEST_DIR)/%$X,$(UNIT_TEST_PROGRAMS))
+UNIT_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
+UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o
+
 # xdiff and reftable libs may in turn depend on what is in libgit.a
 GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
 EXTLIBS =
@@ -2672,6 +2680,7 @@ OBJECTS += $(TEST_OBJS)
 OBJECTS += $(XDIFF_OBJS)
 OBJECTS += $(FUZZ_OBJS)
 OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
+OBJECTS += $(UNIT_TEST_OBJS)

 ifndef NO_CURL
 	OBJECTS += http.o http-walker.o remote-curl.o
@@ -3167,7 +3176,7 @@ endif

 test_bindir_programs := $(patsubst %,bin-wrappers/%,$(BINDIR_PROGRAMS_NEED_X) $(BINDIR_PROGRAMS_NO_X) $(TEST_PROGRAMS_NEED_X))

-all:: $(TEST_PROGRAMS) $(test_bindir_programs)
+all:: $(TEST_PROGRAMS) $(test_bindir_programs) $(UNIT_TEST_PROGS)

 bin-wrappers/%: wrap-for-bin.sh
 	$(call mkdir_p_parent_template)
@@ -3592,7 +3601,7 @@ endif

 artifacts-tar:: $(ALL_COMMANDS_TO_INSTALL) $(SCRIPT_LIB) $(OTHER_PROGRAMS) \
 		GIT-BUILD-OPTIONS $(TEST_PROGRAMS) $(test_bindir_programs) \
-		$(MOFILES)
+		$(UNIT_TEST_PROGS) $(MOFILES)
 	$(QUIET_SUBDIR0)templates $(QUIET_SUBDIR1) \
 		SHELL_PATH='$(SHELL_PATH_SQ)' PERL_PATH='$(PERL_PATH_SQ)'
 	test -n "$(ARTIFACTS_DIRECTORY)"
@@ -3653,7 +3662,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(OBJECTS)
 	$(RM) $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(REFTABLE_TEST_LIB)
 	$(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) $(OTHER_PROGRAMS)
-	$(RM) $(TEST_PROGRAMS)
+	$(RM) $(TEST_PROGRAMS) $(UNIT_TEST_PROGS)
 	$(RM) $(FUZZ_PROGRAMS)
 	$(RM) $(SP_OBJ)
 	$(RM) $(HCC)
@@ -3831,3 +3840,12 @@ $(FUZZ_PROGRAMS): all
 		$(XDIFF_OBJS) $(EXTLIBS) git.o $@.o $(LIB_FUZZING_ENGINE) -o $@

 fuzz-all: $(FUZZ_PROGRAMS)
+
+$(UNIT_TEST_PROGS): $(UNIT_TEST_DIR)/%$X: $(UNIT_TEST_DIR)/%.o $(UNIT_TEST_DIR)/test-lib.o $(GITLIBS) GIT-LDFLAGS
+	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \
+		$(filter %.o,$^) $(filter %.a,$^) $(LIBS)
+
+.PHONY: build-unit-tests unit-tests
+build-unit-tests: $(UNIT_TEST_PROGS)
+unit-tests: $(UNIT_TEST_PROGS)
+	$(MAKE) -C t/ unit-tests
diff --git a/t/Makefile b/t/Makefile
index 3e00cdd801..92864cdf28 100644
--- a/t/Makefile
+++ b/t/Makefile
@@ -41,6 +41,7 @@ TPERF = $(sort $(wildcard perf/p[0-9][0-9][0-9][0-9]-*.sh))
 TINTEROP = $(sort $(wildcard interop/i[0-9][0-9][0-9][0-9]-*.sh))
 CHAINLINTTESTS = $(sort $(patsubst chainlint/%.test,%,$(wildcard chainlint/*.test)))
 CHAINLINT = '$(PERL_PATH_SQ)' chainlint.pl
+UNIT_TESTS = $(sort $(filter-out %.h %.c %.o unit-tests/t-basic%,$(wildcard unit-tests/*)))

 # `test-chainlint` (which is a dependency of `test-lint`, `test` and `prove`)
 # checks all tests in all scripts via a single invocation, so tell individual
@@ -65,6 +66,13 @@ prove: pre-clean check-chainlint $(TEST_LINT)
 $(T):
 	@echo "*** $@ ***"; '$(TEST_SHELL_PATH_SQ)' $@ $(GIT_TEST_OPTS)

+$(UNIT_TESTS):
+	@echo "*** $@ ***"; $@
+
+.PHONY: unit-tests
+unit-tests:
+	@echo "*** prove - unit tests ***"; $(PROVE) $(GIT_PROVE_OPTS) $(UNIT_TESTS)
+
 pre-clean:
 	$(RM) -r '$(TEST_RESULTS_DIRECTORY_SQ)'

@@ -149,4 +157,4 @@ perf:
 	$(MAKE) -C perf/ all

 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
-	check-chainlint clean-chainlint test-chainlint
+	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
diff --git a/t/t0080-unit-test-output.sh b/t/t0080-unit-test-output.sh
new file mode 100755
index 0000000000..c60e402260
--- /dev/null
+++ b/t/t0080-unit-test-output.sh
@@ -0,0 +1,58 @@
+#!/bin/sh
+
+test_description='Test the output of the unit test framework'
+
+. ./test-lib.sh
+
+test_expect_success 'TAP output from unit tests' '
+	cat >expect <<-EOF &&
+	ok 1 - passing test
+	ok 2 - passing test and assertion return 0
+	# check "1 == 2" failed at t/unit-tests/t-basic.c:68
+	#    left: 1
+	#   right: 2
+	not ok 3 - failing test
+	ok 4 - failing test and assertion return -1
+	not ok 5 - passing TEST_TODO() # TODO
+	ok 6 - passing TEST_TODO() returns 0
+	# todo check ${SQ}check(x)${SQ} succeeded at t/unit-tests/t-basic.c:17
+	not ok 7 - failing TEST_TODO()
+	ok 8 - failing TEST_TODO() returns -1
+	# check "0" failed at t/unit-tests/t-basic.c:22
+	# skipping test - missing prerequisite
+	# skipping check ${SQ}1${SQ} at t/unit-tests/t-basic.c:24
+	ok 9 - test_skip() # SKIP
+	ok 10 - skipped test returns 0
+	# skipping test - missing prerequisite
+	ok 11 - test_skip() inside TEST_TODO() # SKIP
+	ok 12 - test_skip() inside TEST_TODO() returns 0
+	# check "0" failed at t/unit-tests/t-basic.c:40
+	not ok 13 - TEST_TODO() after failing check
+	ok 14 - TEST_TODO() after failing check returns -1
+	# check "0" failed at t/unit-tests/t-basic.c:48
+	not ok 15 - failing check after TEST_TODO()
+	ok 16 - failing check after TEST_TODO() returns -1
+	# check "!strcmp("\thello\\\\", "there\"\n")" failed at t/unit-tests/t-basic.c:53
+	#    left: "\011hello\\\\"
+	#   right: "there\"\012"
+	# check "!strcmp("NULL", NULL)" failed at t/unit-tests/t-basic.c:54
+	#    left: "NULL"
+	#   right: NULL
+	# check "${SQ}a${SQ} == ${SQ}\n${SQ}" failed at t/unit-tests/t-basic.c:55
+	#    left: ${SQ}a${SQ}
+	#   right: ${SQ}\012${SQ}
+	# check "${SQ}\\\\${SQ} == ${SQ}\\${SQ}${SQ}" failed at t/unit-tests/t-basic.c:56
+	#    left: ${SQ}\\\\${SQ}
+	#   right: ${SQ}\\${SQ}${SQ}
+	not ok 17 - messages from failing string and char comparison
+	# BUG: test has no checks at t/unit-tests/t-basic.c:83
+	not ok 18 - test with no checks
+	ok 19 - test with no checks returns -1
+	1..19
+	EOF
+
+	! "$GIT_BUILD_DIR"/t/unit-tests/t-basic >actual &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/unit-tests/.gitignore b/t/unit-tests/.gitignore
new file mode 100644
index 0000000000..e292d58348
--- /dev/null
+++ b/t/unit-tests/.gitignore
@@ -0,0 +1,2 @@
+/t-basic
+/t-strbuf
diff --git a/t/unit-tests/t-basic.c b/t/unit-tests/t-basic.c
new file mode 100644
index 0000000000..ab0b7682c4
--- /dev/null
+++ b/t/unit-tests/t-basic.c
@@ -0,0 +1,87 @@
+#include "test-lib.h"
+
+/* Used to store the return value of check_int(). */
+static int check_res;
+
+/* Used to store the return value of TEST(). */
+static int test_res;
+
+static void t_res(int expect)
+{
+	check_int(check_res, ==, expect);
+	check_int(test_res, ==, expect);
+}
+
+static void t_todo(int x)
+{
+	check_res = TEST_TODO(check(x));
+}
+
+static void t_skip(void)
+{
+	check(0);
+	test_skip("missing prerequisite");
+	check(1);
+}
+
+static int do_skip(void)
+{
+	test_skip("missing prerequisite");
+	return 0;
+}
+
+static void t_skip_todo(void)
+{
+	check_res = TEST_TODO(do_skip());
+}
+
+static void t_todo_after_fail(void)
+{
+	check(0);
+	TEST_TODO(check(0));
+}
+
+static void t_fail_after_todo(void)
+{
+	check(1);
+	TEST_TODO(check(0));
+	check(0);
+}
+
+static void t_messages(void)
+{
+	check_str("\thello\\", "there\"\n");
+	check_str("NULL", NULL);
+	check_char('a', ==, '\n');
+	check_char('\\', ==, '\'');
+}
+
+static void t_empty(void)
+{
+	; /* empty */
+}
+
+int cmd_main(int argc, const char **argv)
+{
+	test_res = TEST(check_res = check_int(1, ==, 1), "passing test");
+	TEST(t_res(0), "passing test and assertion return 0");
+	test_res = TEST(check_res = check_int(1, ==, 2), "failing test");
+	TEST(t_res(-1), "failing test and assertion return -1");
+	test_res = TEST(t_todo(0), "passing TEST_TODO()");
+	TEST(t_res(0), "passing TEST_TODO() returns 0");
+	test_res = TEST(t_todo(1), "failing TEST_TODO()");
+	TEST(t_res(-1), "failing TEST_TODO() returns -1");
+	test_res = TEST(t_skip(), "test_skip()");
+	TEST(check_int(test_res, ==, 0), "skipped test returns 0");
+	test_res = TEST(t_skip_todo(), "test_skip() inside TEST_TODO()");
+	TEST(t_res(0), "test_skip() inside TEST_TODO() returns 0");
+	test_res = TEST(t_todo_after_fail(), "TEST_TODO() after failing check");
+	TEST(check_int(test_res, ==, -1), "TEST_TODO() after failing check returns -1");
+	test_res = TEST(t_fail_after_todo(), "failing check after TEST_TODO()");
+	TEST(check_int(test_res, ==, -1), "failing check after TEST_TODO() returns -1");
+	TEST(t_messages(), "messages from failing string and char comparison");
+	test_res = TEST(t_empty(), "test with no checks");
+	TEST(check_int(test_res, ==, -1), "test with no checks returns -1");
+
+	return test_done();
+}
diff --git a/t/unit-tests/t-strbuf.c b/t/unit-tests/t-strbuf.c
new file mode 100644
index 0000000000..561611e242
--- /dev/null
+++ b/t/unit-tests/t-strbuf.c
@@ -0,0 +1,75 @@
+#include "test-lib.h"
+#include "strbuf.h"
+
+/* wrapper that supplies tests with an initialized strbuf */
+static void setup(void (*f)(struct strbuf*, void*), void *data)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	f(&buf, data);
+	strbuf_release(&buf);
+	check_uint(buf.len, ==, 0);
+	check_uint(buf.alloc, ==, 0);
+	check(buf.buf == strbuf_slopbuf);
+	check_char(buf.buf[0], ==, '\0');
+}
+
+static void t_static_init(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	check_uint(buf.len, ==, 0);
+	check_uint(buf.alloc, ==, 0);
+	if (check(buf.buf == strbuf_slopbuf))
+		return; /* avoid de-referencing buf.buf */
+	check_char(buf.buf[0], ==, '\0');
+}
+
+static void t_dynamic_init(void)
+{
+	struct strbuf buf;
+
+	strbuf_init(&buf, 1024);
+	check_uint(buf.len, ==, 0);
+	check_uint(buf.alloc, >=, 1024);
+	check_char(buf.buf[0], ==, '\0');
+	strbuf_release(&buf);
+}
+
+static void t_addch(struct strbuf *buf, void *data)
+{
+	const char *p_ch = data;
+	const char ch = *p_ch;
+
+	strbuf_addch(buf, ch);
+	if (check_uint(buf->len, ==, 1) ||
+	    check_uint(buf->alloc, >, 1))
+		return; /* avoid de-referencing buf->buf */
+	check_char(buf->buf[0], ==, ch);
+	check_char(buf->buf[1], ==, '\0');
+}
+
+static void t_addstr(struct strbuf *buf, void *data)
+{
+	const char *text = data;
+	size_t len = strlen(text);
+
+	strbuf_addstr(buf, text);
+	if (check_uint(buf->len, ==, len) ||
+	    check_uint(buf->alloc, >, len) ||
+	    check_char(buf->buf[len], ==, '\0'))
+	    return;
+	check_str(buf->buf, text);
+}
+
+int cmd_main(int argc, const char **argv)
+{
+	if (TEST(t_static_init(), "static initialization works"))
+		test_skip_all("STRBUF_INIT is broken");
+	TEST(t_dynamic_init(), "dynamic initialization works");
+	TEST(setup(t_addch, "a"), "strbuf_addch adds char");
+	TEST(setup(t_addch, ""), "strbuf_addch adds NUL char");
+	TEST(setup(t_addstr, "hello there"), "strbuf_addstr adds string");
+
+	return test_done();
+}
diff --git a/t/unit-tests/test-lib.c b/t/unit-tests/test-lib.c
new file mode 100644
index 0000000000..70030d587f
--- /dev/null
+++ b/t/unit-tests/test-lib.c
@@ -0,0 +1,329 @@
+#include "test-lib.h"
+
+enum result {
+	RESULT_NONE,
+	RESULT_FAILURE,
+	RESULT_SKIP,
+	RESULT_SUCCESS,
+	RESULT_TODO
+};
+
+static struct {
+	enum result result;
+	int count;
+	unsigned failed :1;
+	unsigned lazy_plan :1;
+	unsigned running :1;
+	unsigned skip_all :1;
+	unsigned todo :1;
+} ctx = {
+	.lazy_plan = 1,
+	.result = RESULT_NONE,
+};
+
+static void msg_with_prefix(const char *prefix, const char *format, va_list ap)
+{
+	fflush(stderr);
+	if (prefix)
+		fprintf(stdout, "%s", prefix);
+	vprintf(format, ap); /* TODO: handle newlines */
+	putc('\n', stdout);
+	fflush(stdout);
+}
+
+void test_msg(const char *format, ...)
+{
+	va_list ap;
+
+	va_start(ap, format);
+	msg_with_prefix("# ", format, ap);
+	va_end(ap);
+}
+
+void test_plan(int count)
+{
+	assert(!ctx.running);
+
+	fflush(stderr);
+	printf("1..%d\n", count);
+	fflush(stdout);
+	ctx.lazy_plan = 0;
+}
+
+int test_done(void)
+{
+	assert(!ctx.running);
+
+	if (ctx.lazy_plan)
+		test_plan(ctx.count);
+
+	return ctx.failed;
+}
+
+void test_skip(const char *format, ...)
+{
+	va_list ap;
+
+	assert(ctx.running);
+
+	ctx.result = RESULT_SKIP;
+	va_start(ap, format);
+	if (format)
+		msg_with_prefix("# skipping test - ", format, ap);
+	va_end(ap);
+}
+
+void test_skip_all(const char *format, ...)
+{
+	va_list ap;
+	const char *prefix;
+
+	if (!ctx.count && ctx.lazy_plan) {
+		/* We have not printed a test plan yet */
+		prefix = "1..0 # SKIP ";
+		ctx.lazy_plan = 0;
+	} else {
+		/* We have already printed a test plan */
+		prefix = "Bail out! # ";
+		ctx.failed = 1;
+	}
+	ctx.skip_all = 1;
+	ctx.result = RESULT_SKIP;
+	va_start(ap, format);
+	msg_with_prefix(prefix, format, ap);
+	va_end(ap);
+}
+
+int test__run_begin(void)
+{
+	assert(!ctx.running);
+
+	ctx.count++;
+	ctx.result = RESULT_NONE;
+	ctx.running = 1;
+
+	return ctx.skip_all;
+}
+
+static void print_description(const char *format, va_list ap)
+{
+	if (format) {
+		fputs(" - ", stdout);
+		vprintf(format, ap);
+	}
+}
+
+int test__run_end(int was_run UNUSED, const char *location, const char *format, ...)
+{
+	va_list ap;
+
+	assert(ctx.running);
+	assert(!ctx.todo);
+
+	fflush(stderr);
+	va_start(ap, format);
+	if (!ctx.skip_all) {
+		switch (ctx.result) {
+		case RESULT_SUCCESS:
+			printf("ok %d", ctx.count);
+			print_description(format, ap);
+			break;
+
+		case RESULT_FAILURE:
+			printf("not ok %d", ctx.count);
+			print_description(format, ap);
+			break;
+
+		case RESULT_TODO:
+			printf("not ok %d", ctx.count);
+			print_description(format, ap);
+			printf(" # TODO");
+			break;
+
+		case RESULT_SKIP:
+			printf("ok %d", ctx.count);
+			print_description(format, ap);
+			printf(" # SKIP");
+			break;
+
+		case RESULT_NONE:
+			test_msg("BUG: test has no checks at %s", location);
+			printf("not ok %d", ctx.count);
+			print_description(format, ap);
+			ctx.result = RESULT_FAILURE;
+			break;
+		}
+	}
+	va_end(ap);
+	ctx.running = 0;
+	if (ctx.skip_all)
+		return 0;
+	putc('\n', stdout);
+	fflush(stdout);
+	ctx.failed |= ctx.result == RESULT_FAILURE;
+
+	return -(ctx.result == RESULT_FAILURE);
+}
+
+static void test_fail(void)
+{
+	assert(ctx.result != RESULT_SKIP);
+
+	ctx.result = RESULT_FAILURE;
+}
+
+static void test_pass(void)
+{
+	assert(ctx.result != RESULT_SKIP);
+
+	if (ctx.result == RESULT_NONE)
+		ctx.result = RESULT_SUCCESS;
+}
+
+static void test_todo(void)
+{
+	assert(ctx.result != RESULT_SKIP);
+
+	if (ctx.result != RESULT_FAILURE)
+		ctx.result = RESULT_TODO;
+}
+
+int test_assert(const char *location, const char *check, int ok)
+{
+	assert(ctx.running);
+
+	if (ctx.result == RESULT_SKIP) {
+		test_msg("skipping check '%s' at %s", check, location);
+		return 0;
+	} else if (!ctx.todo) {
+		if (ok) {
+			test_pass();
+		} else {
+			test_msg("check \"%s\" failed at %s", check, location);
+			test_fail();
+		}
+	}
+
+	return -!ok;
+}
+
+void test__todo_begin(void)
+{
+	assert(ctx.running);
+	assert(!ctx.todo);
+
+	ctx.todo = 1;
+}
+
+int test__todo_end(const char *location, const char *check, int res)
+{
+	assert(ctx.running);
+	assert(ctx.todo);
+
+	ctx.todo = 0;
+	if (ctx.result == RESULT_SKIP)
+		return 0;
+	if (!res) {
+		test_msg("todo check '%s' succeeded at %s", check, location);
+		test_fail();
+	} else {
+		test_todo();
+	}
+
+	return -!res;
+}
+
+int check_bool_loc(const char *loc, const char *check, int ok)
+{
+	return test_assert(loc, check, ok);
+}
+
+union test__tmp test__tmp[2];
+
+int check_int_loc(const char *loc, const char *check, int ok,
+		  intmax_t a, intmax_t b)
+{
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		test_msg("   left: %"PRIdMAX, a);
+		test_msg("  right: %"PRIdMAX, b);
+	}
+
+	return ret;
+}
+
+int check_uint_loc(const char *loc, const char *check, int ok,
+		   uintmax_t a, uintmax_t b)
+{
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		test_msg("   left: %"PRIuMAX, a);
+		test_msg("  right: %"PRIuMAX, b);
+	}
+
+	return ret;
+}
+
+static void print_one_char(char ch, char quote)
+{
+	if ((unsigned char)ch < 0x20u || ch == 0x7f) {
+		/* TODO: improve handling of \a, \b, \f ... */
+		printf("\\%03o", (unsigned char)ch);
+	} else {
+		if (ch == '\\' || ch == quote)
+			putc('\\', stdout);
+		putc(ch, stdout);
+	}
+}
+
+static void print_char(const char *prefix, char ch)
+{
+	printf("# %s: '", prefix);
+	print_one_char(ch, '\'');
+	fputs("'\n", stdout);
+}
+
+int check_char_loc(const char *loc, const char *check, int ok, char a, char b)
+{
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		fflush(stderr);
+		print_char("   left", a);
+		print_char("  right", b);
+		fflush(stdout);
+	}
+
+	return ret;
+}
+
+static void print_str(const char *prefix, const char *str)
+{
+	printf("# %s: ", prefix);
+	if (!str) {
+		fputs("NULL\n", stdout);
+	} else {
+		putc('"', stdout);
+		while (*str)
+			print_one_char(*str++, '"');
+		fputs("\"\n", stdout);
+	}
+}
+
+int check_str_loc(const char *loc, const char *check,
+		  const char *a, const char *b)
+{
+	int ok = (!a && !b) || (a && b && !strcmp(a, b));
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		fflush(stderr);
+		print_str("   left", a);
+		print_str("  right", b);
+		fflush(stdout);
+	}
+
+	return ret;
+}
diff --git a/t/unit-tests/test-lib.h b/t/unit-tests/test-lib.h
new file mode 100644
index 0000000000..720c97c6f8
--- /dev/null
+++ b/t/unit-tests/test-lib.h
@@ -0,0 +1,143 @@
+#ifndef TEST_LIB_H
+#define TEST_LIB_H
+
+#include "git-compat-util.h"
+
+/*
+ * Run a test function, returns 0 if the test succeeds, -1 if it
+ * fails. If test_skip_all() has been called then the test will not be
+ * run. The description for each test should be unique. For example:
+ *
+ *  TEST(test_something(arg1, arg2), "something %d %d", arg1, arg2)
+ */
+#define TEST(t, ...)					\
+	test__run_end(test__run_begin() ? 0 : (t, 1),	\
+		      TEST_LOCATION(),  __VA_ARGS__)
+
+/*
+ * Print a test plan, should be called before any tests. If the number
+ * of tests is not known in advance test_done() will automatically
+ * print a plan at the end of the test program.
+ */
+void test_plan(int count);
+
+/*
+ * test_done() must be called at the end of main(). It will print the
+ * plan if plan() was not called at the beginning of the test program
+ * and returns the exit code for the test program.
+ */
+int test_done(void);
+
+/* Skip the current test. */
+__attribute__((format (printf, 1, 2)))
+void test_skip(const char *format, ...);
+
+/* Skip all remaining tests. */
+__attribute__((format (printf, 1, 2)))
+void test_skip_all(const char *format, ...);
+
+/* Print a diagnostic message to stdout. */
+__attribute__((format (printf, 1, 2)))
+void test_msg(const char *format, ...);
+
+/*
+ * Test checks are built around test_assert(). checks return 0 on
+ * success, -1 on failure. If any check fails then the test will
+ * fail. To create a custom check define a function that wraps
+ * test_assert() and a macro to wrap that function. For example:
+ *
+ *  static int check_oid_loc(const char *loc, const char *check,
+ *			     struct object_id *a, struct object_id *b)
+ *  {
+ *	    int res = test_assert(loc, check, oideq(a, b));
+ *
+ *	    if (res) {
+ *		    test_msg("   left: %s", oid_to_hex(a);
+ *		    test_msg("  right: %s", oid_to_hex(a);
+ *
+ *	    }
+ *	    return res;
+ *  }
+ *
+ *  #define check_oid(a, b) \
+ *	    check_oid_loc(TEST_LOCATION(), "oideq("#a", "#b")", a, b)
+ */
+int test_assert(const char *location, const char *check, int ok);
+
+/* Helper macro to pass the location to checks */
+#define TEST_LOCATION() TEST__MAKE_LOCATION(__LINE__)
+
+/* Check a boolean condition. */
+#define check(x)				\
+	check_bool_loc(TEST_LOCATION(), #x, x)
+int check_bool_loc(const char *loc, const char *check, int ok);
+
+/*
+ * Compare two integers. Prints a message with the two values if the
+ * comparison fails. NB this is not thread safe.
+ */
+#define check_int(a, op, b)						\
+	(test__tmp[0].i = (a), test__tmp[1].i = (b),			\
+	 check_int_loc(TEST_LOCATION(), #a" "#op" "#b,			\
+		       test__tmp[0].i op test__tmp[1].i, a, b))
+int check_int_loc(const char *loc, const char *check, int ok,
+		  intmax_t a, intmax_t b);
+
+/*
+ * Compare two unsigned integers. Prints a message with the two values
+ * if the comparison fails. NB this is not thread safe.
+ */
+#define check_uint(a, op, b)						\
+	(test__tmp[0].u = (a), test__tmp[1].u = (b),			\
+	 check_uint_loc(TEST_LOCATION(), #a" "#op" "#b,			\
+			test__tmp[0].u op test__tmp[1].u, a, b))
+int check_uint_loc(const char *loc, const char *check, int ok,
+		   uintmax_t a, uintmax_t b);
+
+/*
+ * Compare two chars. Prints a message with the two values if the
+ * comparison fails. NB this is not thread safe.
+ */
+#define check_char(a, op, b)						\
+	(test__tmp[0].c = (a), test__tmp[1].c = (b),			\
+	 check_char_loc(TEST_LOCATION(), #a" "#op" "#b,			\
+			test__tmp[0].c op test__tmp[1].c, a, b))
+int check_char_loc(const char *loc, const char *check, int ok,
+		   char a, char b);
+
+/* Check whether two strings are equal. */
+#define check_str(a, b)							\
+	check_str_loc(TEST_LOCATION(), "!strcmp("#a", "#b")", a, b)
+int check_str_loc(const char *loc, const char *check,
+		  const char *a, const char *b);
+
+/*
+ * Wrap a check that is known to fail. If the check succeeds then the
+ * test will fail. Returns 0 if the check fails, -1 if it
+ * succeeds. For example:
+ *
+ *  TEST_TODO(check(0));
+ */
+#define TEST_TODO(check) \
+	(test__todo_begin(), test__todo_end(TEST_LOCATION(), #check, check))
+
+/* Private helpers */
+
+#define TEST__STR(x) #x
+#define TEST__MAKE_LOCATION(line) __FILE__ ":" TEST__STR(line)
+
+union test__tmp {
+	intmax_t i;
+	uintmax_t u;
+	char c;
+};
+
+extern union test__tmp test__tmp[2];
+
+int test__run_begin(void);
+__attribute__((format (printf, 3, 4)))
+int test__run_end(int, const char *, const char *, ...);
+void test__todo_begin(void);
+int test__todo_end(const char *, const char *, int);
+
+#endif /* TEST_LIB_H */

Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 Makefile                    |  24 ++-
 t/Makefile                  |  15 +-
 t/t0080-unit-test-output.sh |  58 +++++++
 t/unit-tests/.gitignore     |   2 +
 t/unit-tests/t-basic.c      |  95 +++++++++++
 t/unit-tests/t-strbuf.c     |  75 ++++++++
 t/unit-tests/test-lib.c     | 329 ++++++++++++++++++++++++++++++++++++
 t/unit-tests/test-lib.h     | 143 ++++++++++++++++
 8 files changed, 737 insertions(+), 4 deletions(-)
 create mode 100755 t/t0080-unit-test-output.sh
 create mode 100644 t/unit-tests/.gitignore
 create mode 100644 t/unit-tests/t-basic.c
 create mode 100644 t/unit-tests/t-strbuf.c
 create mode 100644 t/unit-tests/test-lib.c
 create mode 100644 t/unit-tests/test-lib.h

diff --git a/Makefile b/Makefile
index e440728c24..4016da6e39 100644
--- a/Makefile
+++ b/Makefile
@@ -682,6 +682,8 @@ TEST_BUILTINS_OBJS =
 TEST_OBJS =
 TEST_PROGRAMS_NEED_X =
 THIRD_PARTY_SOURCES =
+UNIT_TEST_PROGRAMS =
+UNIT_TEST_DIR = t/unit-tests
 
 # Having this variable in your environment would break pipelines because
 # you cause "cd" to echo its destination to stdout.  It can also take
@@ -1331,6 +1333,12 @@ THIRD_PARTY_SOURCES += compat/regex/%
 THIRD_PARTY_SOURCES += sha1collisiondetection/%
 THIRD_PARTY_SOURCES += sha1dc/%
 
+UNIT_TEST_PROGRAMS += t-basic
+UNIT_TEST_PROGRAMS += t-strbuf
+UNIT_TEST_PROGS = $(patsubst %,$(UNIT_TEST_DIR)/%$X,$(UNIT_TEST_PROGRAMS))
+UNIT_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
+UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o
+
 # xdiff and reftable libs may in turn depend on what is in libgit.a
 GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
 EXTLIBS =
@@ -2672,6 +2680,7 @@ OBJECTS += $(TEST_OBJS)
 OBJECTS += $(XDIFF_OBJS)
 OBJECTS += $(FUZZ_OBJS)
 OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
+OBJECTS += $(UNIT_TEST_OBJS)
 
 ifndef NO_CURL
 	OBJECTS += http.o http-walker.o remote-curl.o
@@ -3167,7 +3176,7 @@ endif
 
 test_bindir_programs := $(patsubst %,bin-wrappers/%,$(BINDIR_PROGRAMS_NEED_X) $(BINDIR_PROGRAMS_NO_X) $(TEST_PROGRAMS_NEED_X))
 
-all:: $(TEST_PROGRAMS) $(test_bindir_programs)
+all:: $(TEST_PROGRAMS) $(test_bindir_programs) $(UNIT_TEST_PROGS)
 
 bin-wrappers/%: wrap-for-bin.sh
 	$(call mkdir_p_parent_template)
@@ -3592,7 +3601,7 @@ endif
 
 artifacts-tar:: $(ALL_COMMANDS_TO_INSTALL) $(SCRIPT_LIB) $(OTHER_PROGRAMS) \
 		GIT-BUILD-OPTIONS $(TEST_PROGRAMS) $(test_bindir_programs) \
-		$(MOFILES)
+		$(UNIT_TEST_PROGS) $(MOFILES)
 	$(QUIET_SUBDIR0)templates $(QUIET_SUBDIR1) \
 		SHELL_PATH='$(SHELL_PATH_SQ)' PERL_PATH='$(PERL_PATH_SQ)'
 	test -n "$(ARTIFACTS_DIRECTORY)"
@@ -3653,7 +3662,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(OBJECTS)
 	$(RM) $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(REFTABLE_TEST_LIB)
 	$(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) $(OTHER_PROGRAMS)
-	$(RM) $(TEST_PROGRAMS)
+	$(RM) $(TEST_PROGRAMS) $(UNIT_TEST_PROGS)
 	$(RM) $(FUZZ_PROGRAMS)
 	$(RM) $(SP_OBJ)
 	$(RM) $(HCC)
@@ -3831,3 +3840,12 @@ $(FUZZ_PROGRAMS): all
 		$(XDIFF_OBJS) $(EXTLIBS) git.o $@.o $(LIB_FUZZING_ENGINE) -o $@
 
 fuzz-all: $(FUZZ_PROGRAMS)
+
+$(UNIT_TEST_PROGS): $(UNIT_TEST_DIR)/%$X: $(UNIT_TEST_DIR)/%.o $(UNIT_TEST_DIR)/test-lib.o $(GITLIBS) GIT-LDFLAGS
+	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \
+		$(filter %.o,$^) $(filter %.a,$^) $(LIBS)
+
+.PHONY: build-unit-tests unit-tests
+build-unit-tests: $(UNIT_TEST_PROGS)
+unit-tests: $(UNIT_TEST_PROGS)
+	$(MAKE) -C t/ unit-tests
diff --git a/t/Makefile b/t/Makefile
index 3e00cdd801..2db8b3adb1 100644
--- a/t/Makefile
+++ b/t/Makefile
@@ -17,6 +17,7 @@ TAR ?= $(TAR)
 RM ?= rm -f
 PROVE ?= prove
 DEFAULT_TEST_TARGET ?= test
+DEFAULT_UNIT_TEST_TARGET ?= unit-tests-raw
 TEST_LINT ?= test-lint
 
 ifdef TEST_OUTPUT_DIRECTORY
@@ -41,6 +42,7 @@ TPERF = $(sort $(wildcard perf/p[0-9][0-9][0-9][0-9]-*.sh))
 TINTEROP = $(sort $(wildcard interop/i[0-9][0-9][0-9][0-9]-*.sh))
 CHAINLINTTESTS = $(sort $(patsubst chainlint/%.test,%,$(wildcard chainlint/*.test)))
 CHAINLINT = '$(PERL_PATH_SQ)' chainlint.pl
+UNIT_TESTS = $(sort $(filter-out %.h %.c %.o unit-tests/t-basic%,$(wildcard unit-tests/*)))
 
 # `test-chainlint` (which is a dependency of `test-lint`, `test` and `prove`)
 # checks all tests in all scripts via a single invocation, so tell individual
@@ -65,6 +67,17 @@ prove: pre-clean check-chainlint $(TEST_LINT)
 $(T):
 	@echo "*** $@ ***"; '$(TEST_SHELL_PATH_SQ)' $@ $(GIT_TEST_OPTS)
 
+$(UNIT_TESTS):
+	@echo "*** $@ ***"; $@
+
+.PHONY: unit-tests unit-tests-raw unit-tests-prove
+unit-tests: $(DEFAULT_UNIT_TEST_TARGET)
+
+unit-tests-raw: $(UNIT_TESTS)
+
+unit-tests-prove:
+	@echo "*** prove - unit tests ***"; $(PROVE) $(GIT_PROVE_OPTS) $(UNIT_TESTS)
+
 pre-clean:
 	$(RM) -r '$(TEST_RESULTS_DIRECTORY_SQ)'
 
@@ -149,4 +162,4 @@ perf:
 	$(MAKE) -C perf/ all
 
 .PHONY: pre-clean $(T) aggregate-results clean valgrind perf \
-	check-chainlint clean-chainlint test-chainlint
+	check-chainlint clean-chainlint test-chainlint $(UNIT_TESTS)
diff --git a/t/t0080-unit-test-output.sh b/t/t0080-unit-test-output.sh
new file mode 100755
index 0000000000..e0fc07d1e5
--- /dev/null
+++ b/t/t0080-unit-test-output.sh
@@ -0,0 +1,58 @@
+#!/bin/sh
+
+test_description='Test the output of the unit test framework'
+
+. ./test-lib.sh
+
+test_expect_success 'TAP output from unit tests' '
+	cat >expect <<-EOF &&
+	ok 1 - passing test
+	ok 2 - passing test and assertion return 0
+	# check "1 == 2" failed at t/unit-tests/t-basic.c:76
+	#    left: 1
+	#   right: 2
+	not ok 3 - failing test
+	ok 4 - failing test and assertion return -1
+	not ok 5 - passing TEST_TODO() # TODO
+	ok 6 - passing TEST_TODO() returns 0
+	# todo check ${SQ}check(x)${SQ} succeeded at t/unit-tests/t-basic.c:25
+	not ok 7 - failing TEST_TODO()
+	ok 8 - failing TEST_TODO() returns -1
+	# check "0" failed at t/unit-tests/t-basic.c:30
+	# skipping test - missing prerequisite
+	# skipping check ${SQ}1${SQ} at t/unit-tests/t-basic.c:32
+	ok 9 - test_skip() # SKIP
+	ok 10 - skipped test returns 0
+	# skipping test - missing prerequisite
+	ok 11 - test_skip() inside TEST_TODO() # SKIP
+	ok 12 - test_skip() inside TEST_TODO() returns 0
+	# check "0" failed at t/unit-tests/t-basic.c:48
+	not ok 13 - TEST_TODO() after failing check
+	ok 14 - TEST_TODO() after failing check returns -1
+	# check "0" failed at t/unit-tests/t-basic.c:56
+	not ok 15 - failing check after TEST_TODO()
+	ok 16 - failing check after TEST_TODO() returns -1
+	# check "!strcmp("\thello\\\\", "there\"\n")" failed at t/unit-tests/t-basic.c:61
+	#    left: "\011hello\\\\"
+	#   right: "there\"\012"
+	# check "!strcmp("NULL", NULL)" failed at t/unit-tests/t-basic.c:62
+	#    left: "NULL"
+	#   right: NULL
+	# check "${SQ}a${SQ} == ${SQ}\n${SQ}" failed at t/unit-tests/t-basic.c:63
+	#    left: ${SQ}a${SQ}
+	#   right: ${SQ}\012${SQ}
+	# check "${SQ}\\\\${SQ} == ${SQ}\\${SQ}${SQ}" failed at t/unit-tests/t-basic.c:64
+	#    left: ${SQ}\\\\${SQ}
+	#   right: ${SQ}\\${SQ}${SQ}
+	not ok 17 - messages from failing string and char comparison
+	# BUG: test has no checks at t/unit-tests/t-basic.c:91
+	not ok 18 - test with no checks
+	ok 19 - test with no checks returns -1
+	1..19
+	EOF
+
+	! "$GIT_BUILD_DIR"/t/unit-tests/t-basic >actual &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/unit-tests/.gitignore b/t/unit-tests/.gitignore
new file mode 100644
index 0000000000..e292d58348
--- /dev/null
+++ b/t/unit-tests/.gitignore
@@ -0,0 +1,2 @@
+/t-basic
+/t-strbuf
diff --git a/t/unit-tests/t-basic.c b/t/unit-tests/t-basic.c
new file mode 100644
index 0000000000..d20f444fab
--- /dev/null
+++ b/t/unit-tests/t-basic.c
@@ -0,0 +1,95 @@
+#include "test-lib.h"
+
+/*
+ * The purpose of this "unit test" is to verify a few invariants of the unit
+ * test framework itself, as well as to provide examples of output from actually
+ * failing tests. As such, it is intended that this test fails, and thus it
+ * should not be run as part of `make unit-tests`. Instead, we verify it behaves
+ * as expected in the integration test t0080-unit-test-output.sh
+ */
+
+/* Used to store the return value of check_int(). */
+static int check_res;
+
+/* Used to store the return value of TEST(). */
+static int test_res;
+
+static void t_res(int expect)
+{
+	check_int(check_res, ==, expect);
+	check_int(test_res, ==, expect);
+}
+
+static void t_todo(int x)
+{
+	check_res = TEST_TODO(check(x));
+}
+
+static void t_skip(void)
+{
+	check(0);
+	test_skip("missing prerequisite");
+	check(1);
+}
+
+static int do_skip(void)
+{
+	test_skip("missing prerequisite");
+	return 0;
+}
+
+static void t_skip_todo(void)
+{
+	check_res = TEST_TODO(do_skip());
+}
+
+static void t_todo_after_fail(void)
+{
+	check(0);
+	TEST_TODO(check(0));
+}
+
+static void t_fail_after_todo(void)
+{
+	check(1);
+	TEST_TODO(check(0));
+	check(0);
+}
+
+static void t_messages(void)
+{
+	check_str("\thello\\", "there\"\n");
+	check_str("NULL", NULL);
+	check_char('a', ==, '\n');
+	check_char('\\', ==, '\'');
+}
+
+static void t_empty(void)
+{
+	; /* empty */
+}
+
+int cmd_main(int argc, const char **argv)
+{
+	test_res = TEST(check_res = check_int(1, ==, 1), "passing test");
+	TEST(t_res(0), "passing test and assertion return 0");
+	test_res = TEST(check_res = check_int(1, ==, 2), "failing test");
+	TEST(t_res(-1), "failing test and assertion return -1");
+	test_res = TEST(t_todo(0), "passing TEST_TODO()");
+	TEST(t_res(0), "passing TEST_TODO() returns 0");
+	test_res = TEST(t_todo(1), "failing TEST_TODO()");
+	TEST(t_res(-1), "failing TEST_TODO() returns -1");
+	test_res = TEST(t_skip(), "test_skip()");
+	TEST(check_int(test_res, ==, 0), "skipped test returns 0");
+	test_res = TEST(t_skip_todo(), "test_skip() inside TEST_TODO()");
+	TEST(t_res(0), "test_skip() inside TEST_TODO() returns 0");
+	test_res = TEST(t_todo_after_fail(), "TEST_TODO() after failing check");
+	TEST(check_int(test_res, ==, -1), "TEST_TODO() after failing check returns -1");
+	test_res = TEST(t_fail_after_todo(), "failing check after TEST_TODO()");
+	TEST(check_int(test_res, ==, -1), "failing check after TEST_TODO() returns -1");
+	TEST(t_messages(), "messages from failing string and char comparison");
+	test_res = TEST(t_empty(), "test with no checks");
+	TEST(check_int(test_res, ==, -1), "test with no checks returns -1");
+
+	return test_done();
+}
diff --git a/t/unit-tests/t-strbuf.c b/t/unit-tests/t-strbuf.c
new file mode 100644
index 0000000000..561611e242
--- /dev/null
+++ b/t/unit-tests/t-strbuf.c
@@ -0,0 +1,75 @@
+#include "test-lib.h"
+#include "strbuf.h"
+
+/* wrapper that supplies tests with an initialized strbuf */
+static void setup(void (*f)(struct strbuf*, void*), void *data)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	f(&buf, data);
+	strbuf_release(&buf);
+	check_uint(buf.len, ==, 0);
+	check_uint(buf.alloc, ==, 0);
+	check(buf.buf == strbuf_slopbuf);
+	check_char(buf.buf[0], ==, '\0');
+}
+
+static void t_static_init(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	check_uint(buf.len, ==, 0);
+	check_uint(buf.alloc, ==, 0);
+	if (check(buf.buf == strbuf_slopbuf))
+		return; /* avoid de-referencing buf.buf */
+	check_char(buf.buf[0], ==, '\0');
+}
+
+static void t_dynamic_init(void)
+{
+	struct strbuf buf;
+
+	strbuf_init(&buf, 1024);
+	check_uint(buf.len, ==, 0);
+	check_uint(buf.alloc, >=, 1024);
+	check_char(buf.buf[0], ==, '\0');
+	strbuf_release(&buf);
+}
+
+static void t_addch(struct strbuf *buf, void *data)
+{
+	const char *p_ch = data;
+	const char ch = *p_ch;
+
+	strbuf_addch(buf, ch);
+	if (check_uint(buf->len, ==, 1) ||
+	    check_uint(buf->alloc, >, 1))
+		return; /* avoid de-referencing buf->buf */
+	check_char(buf->buf[0], ==, ch);
+	check_char(buf->buf[1], ==, '\0');
+}
+
+static void t_addstr(struct strbuf *buf, void *data)
+{
+	const char *text = data;
+	size_t len = strlen(text);
+
+	strbuf_addstr(buf, text);
+	if (check_uint(buf->len, ==, len) ||
+	    check_uint(buf->alloc, >, len) ||
+	    check_char(buf->buf[len], ==, '\0'))
+	    return;
+	check_str(buf->buf, text);
+}
+
+int cmd_main(int argc, const char **argv)
+{
+	if (TEST(t_static_init(), "static initialization works"))
+		test_skip_all("STRBUF_INIT is broken");
+	TEST(t_dynamic_init(), "dynamic initialization works");
+	TEST(setup(t_addch, "a"), "strbuf_addch adds char");
+	TEST(setup(t_addch, ""), "strbuf_addch adds NUL char");
+	TEST(setup(t_addstr, "hello there"), "strbuf_addstr adds string");
+
+	return test_done();
+}
diff --git a/t/unit-tests/test-lib.c b/t/unit-tests/test-lib.c
new file mode 100644
index 0000000000..70030d587f
--- /dev/null
+++ b/t/unit-tests/test-lib.c
@@ -0,0 +1,329 @@
+#include "test-lib.h"
+
+enum result {
+	RESULT_NONE,
+	RESULT_FAILURE,
+	RESULT_SKIP,
+	RESULT_SUCCESS,
+	RESULT_TODO
+};
+
+static struct {
+	enum result result;
+	int count;
+	unsigned failed :1;
+	unsigned lazy_plan :1;
+	unsigned running :1;
+	unsigned skip_all :1;
+	unsigned todo :1;
+} ctx = {
+	.lazy_plan = 1,
+	.result = RESULT_NONE,
+};
+
+static void msg_with_prefix(const char *prefix, const char *format, va_list ap)
+{
+	fflush(stderr);
+	if (prefix)
+		fprintf(stdout, "%s", prefix);
+	vprintf(format, ap); /* TODO: handle newlines */
+	putc('\n', stdout);
+	fflush(stdout);
+}
+
+void test_msg(const char *format, ...)
+{
+	va_list ap;
+
+	va_start(ap, format);
+	msg_with_prefix("# ", format, ap);
+	va_end(ap);
+}
+
+void test_plan(int count)
+{
+	assert(!ctx.running);
+
+	fflush(stderr);
+	printf("1..%d\n", count);
+	fflush(stdout);
+	ctx.lazy_plan = 0;
+}
+
+int test_done(void)
+{
+	assert(!ctx.running);
+
+	if (ctx.lazy_plan)
+		test_plan(ctx.count);
+
+	return ctx.failed;
+}
+
+void test_skip(const char *format, ...)
+{
+	va_list ap;
+
+	assert(ctx.running);
+
+	ctx.result = RESULT_SKIP;
+	va_start(ap, format);
+	if (format)
+		msg_with_prefix("# skipping test - ", format, ap);
+	va_end(ap);
+}
+
+void test_skip_all(const char *format, ...)
+{
+	va_list ap;
+	const char *prefix;
+
+	if (!ctx.count && ctx.lazy_plan) {
+		/* We have not printed a test plan yet */
+		prefix = "1..0 # SKIP ";
+		ctx.lazy_plan = 0;
+	} else {
+		/* We have already printed a test plan */
+		prefix = "Bail out! # ";
+		ctx.failed = 1;
+	}
+	ctx.skip_all = 1;
+	ctx.result = RESULT_SKIP;
+	va_start(ap, format);
+	msg_with_prefix(prefix, format, ap);
+	va_end(ap);
+}
+
+int test__run_begin(void)
+{
+	assert(!ctx.running);
+
+	ctx.count++;
+	ctx.result = RESULT_NONE;
+	ctx.running = 1;
+
+	return ctx.skip_all;
+}
+
+static void print_description(const char *format, va_list ap)
+{
+	if (format) {
+		fputs(" - ", stdout);
+		vprintf(format, ap);
+	}
+}
+
+int test__run_end(int was_run UNUSED, const char *location, const char *format, ...)
+{
+	va_list ap;
+
+	assert(ctx.running);
+	assert(!ctx.todo);
+
+	fflush(stderr);
+	va_start(ap, format);
+	if (!ctx.skip_all) {
+		switch (ctx.result) {
+		case RESULT_SUCCESS:
+			printf("ok %d", ctx.count);
+			print_description(format, ap);
+			break;
+
+		case RESULT_FAILURE:
+			printf("not ok %d", ctx.count);
+			print_description(format, ap);
+			break;
+
+		case RESULT_TODO:
+			printf("not ok %d", ctx.count);
+			print_description(format, ap);
+			printf(" # TODO");
+			break;
+
+		case RESULT_SKIP:
+			printf("ok %d", ctx.count);
+			print_description(format, ap);
+			printf(" # SKIP");
+			break;
+
+		case RESULT_NONE:
+			test_msg("BUG: test has no checks at %s", location);
+			printf("not ok %d", ctx.count);
+			print_description(format, ap);
+			ctx.result = RESULT_FAILURE;
+			break;
+		}
+	}
+	va_end(ap);
+	ctx.running = 0;
+	if (ctx.skip_all)
+		return 0;
+	putc('\n', stdout);
+	fflush(stdout);
+	ctx.failed |= ctx.result == RESULT_FAILURE;
+
+	return -(ctx.result == RESULT_FAILURE);
+}
+
+static void test_fail(void)
+{
+	assert(ctx.result != RESULT_SKIP);
+
+	ctx.result = RESULT_FAILURE;
+}
+
+static void test_pass(void)
+{
+	assert(ctx.result != RESULT_SKIP);
+
+	if (ctx.result == RESULT_NONE)
+		ctx.result = RESULT_SUCCESS;
+}
+
+static void test_todo(void)
+{
+	assert(ctx.result != RESULT_SKIP);
+
+	if (ctx.result != RESULT_FAILURE)
+		ctx.result = RESULT_TODO;
+}
+
+int test_assert(const char *location, const char *check, int ok)
+{
+	assert(ctx.running);
+
+	if (ctx.result == RESULT_SKIP) {
+		test_msg("skipping check '%s' at %s", check, location);
+		return 0;
+	} else if (!ctx.todo) {
+		if (ok) {
+			test_pass();
+		} else {
+			test_msg("check \"%s\" failed at %s", check, location);
+			test_fail();
+		}
+	}
+
+	return -!ok;
+}
+
+void test__todo_begin(void)
+{
+	assert(ctx.running);
+	assert(!ctx.todo);
+
+	ctx.todo = 1;
+}
+
+int test__todo_end(const char *location, const char *check, int res)
+{
+	assert(ctx.running);
+	assert(ctx.todo);
+
+	ctx.todo = 0;
+	if (ctx.result == RESULT_SKIP)
+		return 0;
+	if (!res) {
+		test_msg("todo check '%s' succeeded at %s", check, location);
+		test_fail();
+	} else {
+		test_todo();
+	}
+
+	return -!res;
+}
+
+int check_bool_loc(const char *loc, const char *check, int ok)
+{
+	return test_assert(loc, check, ok);
+}
+
+union test__tmp test__tmp[2];
+
+int check_int_loc(const char *loc, const char *check, int ok,
+		  intmax_t a, intmax_t b)
+{
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		test_msg("   left: %"PRIdMAX, a);
+		test_msg("  right: %"PRIdMAX, b);
+	}
+
+	return ret;
+}
+
+int check_uint_loc(const char *loc, const char *check, int ok,
+		   uintmax_t a, uintmax_t b)
+{
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		test_msg("   left: %"PRIuMAX, a);
+		test_msg("  right: %"PRIuMAX, b);
+	}
+
+	return ret;
+}
+
+static void print_one_char(char ch, char quote)
+{
+	if ((unsigned char)ch < 0x20u || ch == 0x7f) {
+		/* TODO: improve handling of \a, \b, \f ... */
+		printf("\\%03o", (unsigned char)ch);
+	} else {
+		if (ch == '\\' || ch == quote)
+			putc('\\', stdout);
+		putc(ch, stdout);
+	}
+}
+
+static void print_char(const char *prefix, char ch)
+{
+	printf("# %s: '", prefix);
+	print_one_char(ch, '\'');
+	fputs("'\n", stdout);
+}
+
+int check_char_loc(const char *loc, const char *check, int ok, char a, char b)
+{
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		fflush(stderr);
+		print_char("   left", a);
+		print_char("  right", b);
+		fflush(stdout);
+	}
+
+	return ret;
+}
+
+static void print_str(const char *prefix, const char *str)
+{
+	printf("# %s: ", prefix);
+	if (!str) {
+		fputs("NULL\n", stdout);
+	} else {
+		putc('"', stdout);
+		while (*str)
+			print_one_char(*str++, '"');
+		fputs("\"\n", stdout);
+	}
+}
+
+int check_str_loc(const char *loc, const char *check,
+		  const char *a, const char *b)
+{
+	int ok = (!a && !b) || (a && b && !strcmp(a, b));
+	int ret = test_assert(loc, check, ok);
+
+	if (ret) {
+		fflush(stderr);
+		print_str("   left", a);
+		print_str("  right", b);
+		fflush(stdout);
+	}
+
+	return ret;
+}
diff --git a/t/unit-tests/test-lib.h b/t/unit-tests/test-lib.h
new file mode 100644
index 0000000000..720c97c6f8
--- /dev/null
+++ b/t/unit-tests/test-lib.h
@@ -0,0 +1,143 @@
+#ifndef TEST_LIB_H
+#define TEST_LIB_H
+
+#include "git-compat-util.h"
+
+/*
+ * Run a test function, returns 0 if the test succeeds, -1 if it
+ * fails. If test_skip_all() has been called then the test will not be
+ * run. The description for each test should be unique. For example:
+ *
+ *  TEST(test_something(arg1, arg2), "something %d %d", arg1, arg2)
+ */
+#define TEST(t, ...)					\
+	test__run_end(test__run_begin() ? 0 : (t, 1),	\
+		      TEST_LOCATION(),  __VA_ARGS__)
+
+/*
+ * Print a test plan, should be called before any tests. If the number
+ * of tests is not known in advance test_done() will automatically
+ * print a plan at the end of the test program.
+ */
+void test_plan(int count);
+
+/*
+ * test_done() must be called at the end of main(). It will print the
+ * plan if plan() was not called at the beginning of the test program
+ * and returns the exit code for the test program.
+ */
+int test_done(void);
+
+/* Skip the current test. */
+__attribute__((format (printf, 1, 2)))
+void test_skip(const char *format, ...);
+
+/* Skip all remaining tests. */
+__attribute__((format (printf, 1, 2)))
+void test_skip_all(const char *format, ...);
+
+/* Print a diagnostic message to stdout. */
+__attribute__((format (printf, 1, 2)))
+void test_msg(const char *format, ...);
+
+/*
+ * Test checks are built around test_assert(). checks return 0 on
+ * success, -1 on failure. If any check fails then the test will
+ * fail. To create a custom check define a function that wraps
+ * test_assert() and a macro to wrap that function. For example:
+ *
+ *  static int check_oid_loc(const char *loc, const char *check,
+ *			     struct object_id *a, struct object_id *b)
+ *  {
+ *	    int res = test_assert(loc, check, oideq(a, b));
+ *
+ *	    if (res) {
+ *		    test_msg("   left: %s", oid_to_hex(a);
+ *		    test_msg("  right: %s", oid_to_hex(a);
+ *
+ *	    }
+ *	    return res;
+ *  }
+ *
+ *  #define check_oid(a, b) \
+ *	    check_oid_loc(TEST_LOCATION(), "oideq("#a", "#b")", a, b)
+ */
+int test_assert(const char *location, const char *check, int ok);
+
+/* Helper macro to pass the location to checks */
+#define TEST_LOCATION() TEST__MAKE_LOCATION(__LINE__)
+
+/* Check a boolean condition. */
+#define check(x)				\
+	check_bool_loc(TEST_LOCATION(), #x, x)
+int check_bool_loc(const char *loc, const char *check, int ok);
+
+/*
+ * Compare two integers. Prints a message with the two values if the
+ * comparison fails. NB this is not thread safe.
+ */
+#define check_int(a, op, b)						\
+	(test__tmp[0].i = (a), test__tmp[1].i = (b),			\
+	 check_int_loc(TEST_LOCATION(), #a" "#op" "#b,			\
+		       test__tmp[0].i op test__tmp[1].i, a, b))
+int check_int_loc(const char *loc, const char *check, int ok,
+		  intmax_t a, intmax_t b);
+
+/*
+ * Compare two unsigned integers. Prints a message with the two values
+ * if the comparison fails. NB this is not thread safe.
+ */
+#define check_uint(a, op, b)						\
+	(test__tmp[0].u = (a), test__tmp[1].u = (b),			\
+	 check_uint_loc(TEST_LOCATION(), #a" "#op" "#b,			\
+			test__tmp[0].u op test__tmp[1].u, a, b))
+int check_uint_loc(const char *loc, const char *check, int ok,
+		   uintmax_t a, uintmax_t b);
+
+/*
+ * Compare two chars. Prints a message with the two values if the
+ * comparison fails. NB this is not thread safe.
+ */
+#define check_char(a, op, b)						\
+	(test__tmp[0].c = (a), test__tmp[1].c = (b),			\
+	 check_char_loc(TEST_LOCATION(), #a" "#op" "#b,			\
+			test__tmp[0].c op test__tmp[1].c, a, b))
+int check_char_loc(const char *loc, const char *check, int ok,
+		   char a, char b);
+
+/* Check whether two strings are equal. */
+#define check_str(a, b)							\
+	check_str_loc(TEST_LOCATION(), "!strcmp("#a", "#b")", a, b)
+int check_str_loc(const char *loc, const char *check,
+		  const char *a, const char *b);
+
+/*
+ * Wrap a check that is known to fail. If the check succeeds then the
+ * test will fail. Returns 0 if the check fails, -1 if it
+ * succeeds. For example:
+ *
+ *  TEST_TODO(check(0));
+ */
+#define TEST_TODO(check) \
+	(test__todo_begin(), test__todo_end(TEST_LOCATION(), #check, check))
+
+/* Private helpers */
+
+#define TEST__STR(x) #x
+#define TEST__MAKE_LOCATION(line) __FILE__ ":" TEST__STR(line)
+
+union test__tmp {
+	intmax_t i;
+	uintmax_t u;
+	char c;
+};
+
+extern union test__tmp test__tmp[2];
+
+int test__run_begin(void);
+__attribute__((format (printf, 3, 4)))
+int test__run_end(int, const char *, const char *, ...);
+void test__todo_begin(void);
+int test__todo_end(const char *, const char *, int);
+
+#endif /* TEST_LIB_H */
-- 
2.41.0.694.ge786442a9b-goog
Previous: Josh SteadmonNext: Junio C Hamano
Message 11 of 67 in “unit tests: Add a project plan document”
  1. unit tests: Add a project plan documentJosh Steadmon, Jun 30, 2023
  2. Junio C HamanoJul 1, 2023
  3. Junio C HamanoJul 1, 2023
  4. unit tests: Add a project plan documentJosh Steadmon, Aug 7, 2023
  5. Phillip WoodAug 14, 2023
  6. Josh SteadmonAug 15, 2023
  7. Phillip WoodAug 17, 2023
  8. 0/3 Add unit test framework and project plan MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bitJosh Steadmon, Aug 16, 2023
  9. 3/3 ci: run unit tests in CIJosh Steadmon, Aug 16, 2023
  10. 1/3 unit tests: Add a project plan documentJosh Steadmon, Aug 16, 2023
  11. 2/3 unit tests: add TAP unit test frameworkJosh Steadmon, Aug 16, 2023
  12. Junio C HamanoAug 17, 2023
  13. Junio C HamanoAug 17, 2023
  14. Josh SteadmonAug 17, 2023
  15. 0/3 Add unit test framework and project planJosh Steadmon, Aug 17, 2023
  16. 3/3 ci: run unit tests in CIJosh Steadmon, Aug 17, 2023
  17. 1/3 unit tests: Add a project plan documentJosh Steadmon, Aug 17, 2023
  18. 2/3 unit tests: add TAP unit test frameworkJosh Steadmon, Aug 17, 2023
  19. Junio C HamanoAug 18, 2023
  20. Junio C HamanoSep 22, 2023
  21. phillip.wood123@gmail.comSep 24, 2023
  22. Junio C HamanoSep 25, 2023
  23. Josh SteadmonOct 6, 2023
  24. Josh SteadmonOct 9, 2023
  25. Junio C HamanoAug 17, 2023
  26. Josh SteadmonAug 24, 2023
  27. Junio C HamanoSep 13, 2023
  28. 0/3 Add unit test framework and project planJosh Steadmon, Oct 9, 2023
  29. 1/3 unit tests: Add a project plan documentJosh Steadmon, Oct 9, 2023
  30. Oswald BuddenhagenOct 10, 2023
  31. Josh SteadmonOct 11, 2023
  32. Oswald BuddenhagenOct 11, 2023
  33. Josh SteadmonNov 1, 2023
  34. Christian CouderOct 27, 2023
  35. Josh SteadmonNov 1, 2023
  36. Junio C HamanoNov 1, 2023
  37. 2/3 unit tests: add TAP unit test frameworkJosh Steadmon, Oct 9, 2023
  38. Junio C HamanoOct 11, 2023
  39. 5/3 fixup! unit tests: add TAP unit test frameworkPhillip Wood, Oct 16, 2023
  40. Junio C HamanoOct 16, 2023
  41. Josh SteadmonNov 1, 2023
  42. Junio C HamanoNov 1, 2023
  43. Josh SteadmonNov 1, 2023
  44. Junio C HamanoNov 1, 2023
  45. Christian CouderOct 27, 2023
  46. Josh SteadmonNov 1, 2023
  47. 3/3 ci: run unit tests in CIJosh Steadmon, Oct 9, 2023
  48. Junio C HamanoOct 9, 2023
  49. 0/3 CMake unit test fixupsPhillip Wood, Oct 19, 2023
  50. 1/3 fixup! cmake: also build unit testsPhillip Wood, Oct 19, 2023
  51. 2/3 fixup! artifacts-tar: when including `.dll` files, don't forget the unit-testsPhillip Wood, Oct 19, 2023
  52. 3/3 fixup! cmake: handle also unit testsPhillip Wood, Oct 19, 2023
  53. Junio C HamanoOct 19, 2023
  54. phillip.wood123@gmail.comOct 16, 2023
  55. Josh SteadmonNov 1, 2023
  56. Christian CouderOct 27, 2023
  57. 0/3 Add unit test framework and project planJosh Steadmon, Nov 1, 2023
  58. 1/3 unit tests: Add a project plan documentJosh Steadmon, Nov 1, 2023
  59. 3/3 ci: run unit tests in CIJosh Steadmon, Nov 1, 2023
  60. 2/3 unit tests: add TAP unit test frameworkJosh Steadmon, Nov 1, 2023
  61. Christian CouderNov 3, 2023
  62. Josh SteadmonNov 9, 2023
  63. 0/3 Add unit test framework and project planJosh Steadmon, Nov 9, 2023
  64. 1/3 unit tests: Add a project plan documentJosh Steadmon, Nov 9, 2023
  65. Junio C HamanoNov 9, 2023
  66. 2/3 unit tests: add TAP unit test frameworkJosh Steadmon, Nov 9, 2023
  67. 3/3 ci: run unit tests in CIJosh Steadmon, Nov 9, 2023

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