[PATCH 1/5] t/unit-tests: implement oid helper functions in unit-tests.{c,h}

[Seyi Kuforiji <kuforiji98@gmail.com>]

`get_oid_arbitrary_hex()` and `init_hash_algo()` are both required for
oid-related tests to run without errors. In the current implementation,
both functions are defined and declared in the
`t/unit-tests/lib-oid.{c,h}` which is utilized by oid-related tests in
the homegrown unit tests structure.

Implement equivalent functions in unit-tests.{c,h}. Both these functions
become available for oid-related test files implemented using the clar
testing framework, which requires them. This will be used by subsequent
commits.

Mentored-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Seyi Kuforiji <kuforiji98@gmail.com>
---
 t/unit-tests/unit-test.c | 42 ++++++++++++++++++++++++++++++++++++++++
 t/unit-tests/unit-test.h | 19 ++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/t/unit-tests/unit-test.c b/t/unit-tests/unit-test.c
index fa8818842a..13d54f192a 100644
--- a/t/unit-tests/unit-test.c
+++ b/t/unit-tests/unit-test.c
@@ -1,5 +1,7 @@
 #include "unit-test.h"
+#include "hex.h"
 #include "parse-options.h"
+#include "strbuf.h"
 #include "string-list.h"
 #include "strvec.h"
 
@@ -62,3 +64,43 @@ int cmd_main(int argc, const char **argv)
 	strvec_clear(&args);
 	return ret;
 }
+
+int init_hash_algo(void)
+{
+	static int algo = -1;
+
+	if (algo < 0) {
+		const char *algo_name = getenv("GIT_TEST_DEFAULT_HASH");
+		algo = algo_name ? hash_algo_by_name(algo_name) : GIT_HASH_SHA1;
+
+		cl_assert(algo != GIT_HASH_UNKNOWN);
+	}
+	return algo;
+}
+
+static void cl_parse_oid(const char *hex, struct object_id *oid,
+				       const struct git_hash_algo *algop)
+{
+	int ret;
+	size_t sz = strlen(hex);
+	struct strbuf buf = STRBUF_INIT;
+
+	cl_assert(sz <= algop->hexsz);
+
+	strbuf_add(&buf, hex, sz);
+	strbuf_addchars(&buf, '0', algop->hexsz - sz);
+
+	ret = get_oid_hex_algop(buf.buf, oid, algop);
+	cl_assert_equal_i(ret, 0);
+
+	strbuf_release(&buf);
+}
+
+
+void cl_parse_any_oid(const char *hex, struct object_id *oid)
+{
+	int hash_algo = init_hash_algo();
+
+	cl_assert(hash_algo != GIT_HASH_UNKNOWN);
+	cl_parse_oid(hex, oid, &hash_algos[hash_algo]);
+}
diff --git a/t/unit-tests/unit-test.h b/t/unit-tests/unit-test.h
index 85e5d6a948..ebed51212f 100644
--- a/t/unit-tests/unit-test.h
+++ b/t/unit-tests/unit-test.h
@@ -8,3 +8,22 @@
 	snprintf(desc, sizeof(desc), fmt, __VA_ARGS__); \
 	clar__fail(__FILE__, __func__, __LINE__, "Test failed.", desc, 1); \
 } while (0)
+
+/*
+ * Convert arbitrary hex string to object_id.
+ * For example, passing "abc12" will generate
+ * "abc1200000000000000000000000000000000000" hex of length 40 for SHA-1 and
+ * create object_id with that.
+ * WARNING: passing a string of length more than the hexsz of respective hash
+ * algo is not allowed. The hash algo is decided based on GIT_TEST_DEFAULT_HASH
+ * environment variable.
+ */
+void cl_parse_any_oid(const char *s, struct object_id *oid);
+/*
+ * Returns one of GIT_HASH_{SHA1, SHA256, UNKNOWN} based on the value of
+ * GIT_TEST_DEFAULT_HASH environment variable. The fallback value in the
+ * absence of GIT_TEST_DEFAULT_HASH is GIT_HASH_SHA1. It also uses
+ * cl_assert(algo != GIT_HASH_UNKNOWN) before returning to verify if the
+ * GIT_TEST_DEFAULT_HASH's value is valid or not.
+ */
+int init_hash_algo(void);
-- 
2.47.0.86.g15030f9556