1 files changed, 137 insertions, 0 deletions
diff --git a/tests/object/raw/short.c b/tests/object/raw/short.c
new file mode 100644
index 000000000..813cd86b6
--- /dev/null
+++ b/tests/object/raw/short.c
@@ -0,0 +1,137 @@
+
+#include "clar_libgit2.h"
+
+#include "odb.h"
+#include "hash.h"
+
+void test_object_raw_short__oid_shortener_no_duplicates(void)
+{
+	git_oid_shorten *os;
+	int min_len;
+
+	os = git_oid_shorten_new(0);
+	cl_assert(os != NULL);
+
+	git_oid_shorten_add(os, "22596363b3de40b06f981fb85d82312e8c0ed511");
+	git_oid_shorten_add(os, "ce08fe4884650f067bd5703b6a59a8b3b3c99a09");
+	git_oid_shorten_add(os, "16a0123456789abcdef4b775213c23a8bd74f5e0");
+	min_len = git_oid_shorten_add(os, "ce08fe4884650f067bd5703b6a59a8b3b3c99a09");
+
+	cl_assert(min_len == GIT_OID_HEXSZ + 1);
+
+	git_oid_shorten_free(os);
+}
+
+static int insert_sequential_oids(
+	char ***out, git_oid_shorten *os, int n, int fail)
+{
+	int i, min_len = 0;
+	char numbuf[16];
+	git_oid oid;
+	char **oids = git__calloc(n, sizeof(char *));
+	cl_assert(oids != NULL);
+
+	for (i = 0; i < n; ++i) {
+		p_snprintf(numbuf, sizeof(numbuf), "%u", (unsigned int)i);
+		git_hash_buf(&oid, numbuf, strlen(numbuf));
+
+		oids[i] = git__malloc(GIT_OID_HEXSZ + 1);
+		cl_assert(oids[i]);
+		git_oid_nfmt(oids[i], GIT_OID_HEXSZ + 1, &oid);
+
+		min_len = git_oid_shorten_add(os, oids[i]);
+
+		/* After "fail", we expect git_oid_shorten_add to fail */
+		if (fail >= 0 && i >= fail)
+            cl_assert(min_len < 0);
+		else
+            cl_assert(min_len >= 0);
+	}
+
+	*out = oids;
+
+	return min_len;
+}
+
+static void free_oids(int n, char **oids)
+{
+	int i;
+
+	for (i = 0; i < n; ++i) {
+		git__free(oids[i]);
+	}
+	git__free(oids);
+}
+
+void test_object_raw_short__oid_shortener_stresstest_git_oid_shorten(void)
+{
+#define MAX_OIDS 1000
+
+	git_oid_shorten *os;
+	size_t i, j;
+	int min_len = 0, found_collision;
+	char **oids;
+
+	os = git_oid_shorten_new(0);
+	cl_assert(os != NULL);
+
+	/*
+	 * Insert in the shortener 1000 unique SHA1 ids
+	 */
+	min_len = insert_sequential_oids(&oids, os, MAX_OIDS, MAX_OIDS);
+	cl_assert(min_len > 0);
+
+	/*
+	 * Compare the first `min_char - 1` characters of each
+	 * SHA1 OID. If the minimizer worked, we should find at
+	 * least one collision
+	 */
+	found_collision = 0;
+	for (i = 0; i < MAX_OIDS; ++i) {
+		for (j = i + 1; j < MAX_OIDS; ++j) {
+			if (memcmp(oids[i], oids[j], min_len - 1) == 0)
+				found_collision = 1;
+		}
+	}
+	cl_assert_equal_b(true, found_collision);
+
+	/*
+	 * Compare the first `min_char` characters of each
+	 * SHA1 OID. If the minimizer worked, every single preffix
+	 * should be unique.
+	 */
+	found_collision = 0;
+	for (i = 0; i < MAX_OIDS; ++i) {
+		for (j = i + 1; j < MAX_OIDS; ++j) {
+			if (memcmp(oids[i], oids[j], min_len) == 0)
+				found_collision = 1;
+		}
+	}
+	cl_assert_equal_b(false, found_collision);
+
+	/* cleanup */
+	free_oids(MAX_OIDS, oids);
+	git_oid_shorten_free(os);
+
+#undef MAX_OIDS
+}
+
+void test_object_raw_short__oid_shortener_too_much_oids(void)
+{
+    /* The magic number of oids at which an oid_shortener will fail.
+     * This was experimentally established. */
+#define MAX_OIDS 24556
+
+	git_oid_shorten *os;
+	char **oids;
+
+	os = git_oid_shorten_new(0);
+	cl_assert(os != NULL);
+
+	cl_assert(insert_sequential_oids(&oids, os, MAX_OIDS, MAX_OIDS - 1) < 0);
+
+	free_oids(MAX_OIDS, oids);
+	git_oid_shorten_free(os);
+
+#undef MAX_OIDS
+}