Added test case for new function

tests-clar/core/oid.c

 #include "clar_libgit2.h"
 
 static git_oid id;
+static git_oid idp;
+static git_oid idm;
 const char *str_oid = "ae90f12eea699729ed24555e40b9fd669da12a12";
+const char *str_oid_p = "ae90f12eea699729ed";
+const char *str_oid_m = "ae90f12eea699729ed24555e40b9fd669da12a12oiahs";
 
 void test_core_oid__initialize(void)
 {
 	cl_git_pass(git_oid_fromstr(&id, str_oid));
+	cl_git_pass(git_oid_fromstrp(&idp, str_oid_p));
+	cl_git_pass(git_oid_fromstrp(&idm, str_oid_m));
 }
 
 void test_core_oid__streq(void)
@@ -15,4 +21,12 @@ void test_core_oid__streq(void)
 
 	cl_assert(git_oid_streq(&id, "deadbeef") == -1);
 	cl_assert(git_oid_streq(&id, "I'm not an oid.... :)") == -1);
+	
+	cl_assert(git_oid_streq(&idp, "ae90f12eea699729ed0000000000000000000000") == 0);
+	cl_assert(git_oid_streq(&idp, "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef") == -1);
+
+	cl_assert(git_oid_streq(&idp, "deadbeef") == -1);
+	cl_assert(git_oid_streq(&idp, "I'm not an oid.... :)") == -1);
+	
+	cl_assert(git_oid_cmp(&id, &idm) == 0);
 }