test: slre: add tests for regex library

Inspecting the slre.c code reveals a few bugs; those are easy to
demonstrate with the new '=~' test operator. Before fixing them, let's
add a place to add test cases.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>

MAINTAINERS

@@ -1633,6 +1633,7 @@ M:	Rasmus Villemoes <ravi@prevas.dk>
 S:	Maintained
 F:	include/slre.h
 F:	lib/slre.c
+F:	test/lib/slre.c
 
 SMCCC TRNG
 M:	Etienne Carriere <etienne.carriere@linaro.org>

test/lib/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_SHA256) += test_sha256_hmac.o
 obj-$(CONFIG_HKDF_MBEDTLS) += test_sha256_hkdf.o
 obj-$(CONFIG_GETOPT) += getopt.o
 obj-$(CONFIG_CRC8) += test_crc8.o
+obj-$(CONFIG_REGEX) += slre.o
 obj-$(CONFIG_UT_LIB_CRYPT) += test_crypt.o
 obj-$(CONFIG_UT_TIME) += time.o
 obj-$(CONFIG_$(PHASE_)UT_UNICODE) += unicode.o

test/lib/slre.c

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+#include <test/lib.h>
+#include <test/ut.h>
+#include <slre.h>
+
+struct re_test {
+	const char *str;
+	const char *re;
+	int match;
+};
+
+static const struct re_test re_test[] = {
+	{ "123", "^\\d+$", 1},
+	{ "x23", "^\\d+$", 0},
+	{ "banana", "^([bn]a)*$", 1},
+	{ "panama", "^([bn]a)*$", 0},
+	{}
+};
+
+static int lib_slre(struct unit_test_state *uts)
+{
+	const struct re_test *t;
+
+	for (t = re_test; t->str; t++) {
+		struct slre slre;
+
+		ut_assert(slre_compile(&slre, t->re));
+		ut_assertf(!!slre_match(&slre, t->str, strlen(t->str), NULL) == t->match,
+			   "'%s' unexpectedly %s '%s'\n", t->str,
+			   t->match ? "didn't match" : "matched", t->re);
+	}
+
+	return 0;
+}
+LIB_TEST(lib_slre, 0);