push: add tests for the push negotiation callback

The functionality was meged without including tests, so let's add them
now.

tests/network/remote/push.c

+#include "clar_libgit2.h"
+#include "git2/sys/commit.h"
+
+static git_remote *_remote;
+static git_repository *_repo, *_dummy;
+
+void test_network_remote_push__initialize(void)
+{
+	cl_fixture_sandbox("testrepo.git");
+	git_repository_open(&_repo, "testrepo.git");
+
+	/* We need a repository to have a remote */
+	cl_git_pass(git_repository_init(&_dummy, "dummy.git", true));
+	cl_git_pass(git_remote_create(&_remote, _dummy, "origin", cl_git_path_url("testrepo.git")));
+}
+
+void test_network_remote_push__cleanup(void)
+{
+	git_remote_free(_remote);
+	_remote = NULL;
+
+	git_repository_free(_repo);
+	_repo = NULL;
+
+	git_repository_free(_dummy);
+	_dummy = NULL;
+
+	cl_fixture_cleanup("testrepo.git");
+	cl_fixture_cleanup("dummy.git");
+}
+
+int negotiation_cb(const git_push_update **updates, size_t len, void *payload)
+{
+	const git_push_update *expected = payload;
+
+	cl_assert_equal_i(1, len);
+	cl_assert_equal_s(expected->src_refname, updates[0]->src_refname);
+	cl_assert_equal_s(expected->dst_refname, updates[0]->dst_refname);
+	cl_assert_equal_oid(&expected->src, &updates[0]->src);
+	cl_assert_equal_oid(&expected->dst, &updates[0]->dst);
+
+	return 0;
+}
+
+void test_network_remote_push__delete_notification(void)
+{
+	git_push_options opts = GIT_PUSH_OPTIONS_INIT;
+	git_reference *ref;
+	git_push_update expected;
+	char *refspec = ":refs/heads/master";
+	const git_strarray refspecs = {
+		&refspec,
+		1,
+	};
+
+	cl_git_pass(git_reference_lookup(&ref, _repo, "refs/heads/master"));
+
+	expected.src_refname = "";
+	expected.dst_refname = "refs/heads/master";
+	memset(&expected.dst, 0, sizeof(git_oid));
+	git_oid_cpy(&expected.src, git_reference_target(ref));
+
+	opts.callbacks.push_negotiation = negotiation_cb;
+	opts.callbacks.payload = &expected;
+	cl_git_pass(git_remote_push(_remote, &refspecs, &opts));
+
+	git_reference_free(ref);
+	cl_git_fail_with(GIT_ENOTFOUND, git_reference_lookup(&ref, _repo, "refs/heads/master"));
+
+}
+
+void create_dummy_commit(git_reference **out, git_repository *repo)
+{
+	git_index *index;
+	git_oid tree_id, commit_id;
+	git_signature *sig;
+
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_write_tree(&tree_id, index));
+	git_index_free(index);
+
+	cl_git_pass(git_signature_now(&sig, "Pusher Joe", "pjoe"));
+	cl_git_pass(git_commit_create_from_ids(&commit_id, repo, NULL, sig, sig,
+					       NULL, "Empty tree\n", &tree_id, 0, NULL));
+	cl_git_pass(git_reference_create(out, repo, "refs/heads/empty-tree", &commit_id, true, "commit yo"));
+	git_signature_free(sig);
+}
+
+void test_network_remote_push__create_notification(void)
+{
+	git_push_options opts = GIT_PUSH_OPTIONS_INIT;
+	git_reference *ref;
+	git_push_update expected;
+	char *refspec = "refs/heads/empty-tree";
+	const git_strarray refspecs = {
+		&refspec,
+		1,
+	};
+
+	create_dummy_commit(&ref, _dummy);
+
+	expected.src_refname = "refs/heads/empty-tree";
+	expected.dst_refname = "refs/heads/empty-tree";
+	git_oid_cpy(&expected.dst, git_reference_target(ref));
+	memset(&expected.src, 0, sizeof(git_oid));
+
+	opts.callbacks.push_negotiation = negotiation_cb;
+	opts.callbacks.payload = &expected;
+	cl_git_pass(git_remote_push(_remote, &refspecs, &opts));
+
+	git_reference_free(ref);
+	cl_git_pass(git_reference_lookup(&ref, _repo, "refs/heads/empty-tree"));
+	git_reference_free(ref);
+}