tests: Add lib/hexstrtobin-test test case

Implement unit tests for lib/hexstrtobin module.

Signed-off-by: Anna Karas <aka@semihalf.com>
Change-Id: Id929b07936ea180a798309e5acb1dacf1b396e32
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43088
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
diff --git a/tests/lib/Makefile.inc b/tests/lib/Makefile.inc
index 5d47fea..594c68e 100644
--- a/tests/lib/Makefile.inc
+++ b/tests/lib/Makefile.inc
@@ -2,9 +2,13 @@
 
 tests-y += string-test
 tests-y += b64_decode-test
+tests-y += hexstrtobin-test
 
 string-test-srcs += tests/lib/string-test.c
 string-test-srcs += src/lib/string.c
 
 b64_decode-test-srcs += tests/lib/b64_decode-test.c
 b64_decode-test-srcs += src/lib/b64_decode.c
+
+hexstrtobin-test-srcs += tests/lib/hexstrtobin-test.c
+hexstrtobin-test-srcs += src/lib/hexstrtobin.c