thodg/libgit2

diff --git a/tests/t0403-write.c b/tests/t0403-write.c
new file mode 100644
index 0000000..b1d088d
--- /dev/null
+++ b/tests/t0403-write.c
@@ -0,0 +1,127 @@
+#include "test_lib.h"
+#include "test_helpers.h"
+#include "commit.h"
+
+#include <git/odb.h>
+#include <git/commit.h>
+#include <git/revwalk.h>
+
+static const char *odb_dir = "../resources/sample-odb";
+static const char *commit_ids[] = {
+	"a4a7dce85cf63874e984719f4fdd239f5145052f", /* 0 */
+	"9fd738e8f7967c078dceed8190330fc8648ee56a", /* 1 */
+	"4a202b346bb0fb0db7eff3cffeb3c70babbd2045", /* 2 */
+	"c47800c7266a2be04c571c04d5a6614691ea99bd", /* 3 */
+	"8496071c1b46c854b31185ea97743be6a8774479", /* 4 */
+	"5b5b025afb0b4c913b4c338a42934a3863bf3644", /* 5 */
+};
+static const char *tree_oid = "1810dff58d8a660512d4832e740f692884338ccd";
+
+BEGIN_TEST(writenew_test)
+	git_odb *db;
+	git_repository *repo;
+	git_commit *commit, *parent;
+	git_tree *tree;
+	git_oid id;
+	/* char hex_oid[41]; */
+
+	git_person author = {"Vicent Marti", "vicent@github.com", 123456789};
+	git_person committer = {"Vicent Marti", "vicent@github.com", 987654321};
+
+	must_pass(git_odb_open(&db, odb_dir));
+
+	repo = git_repository_alloc(db);
+	must_be_true(repo != NULL);
+
+	/* Create commit in memory */
+	commit = git_commit_new(repo);
+	must_be_true(commit != NULL);
+
+	/* Add new parent */
+	git_oid_mkstr(&id, commit_ids[4]);
+	parent = git_commit_lookup(repo, &id);
+	must_be_true(parent != NULL);
+
+	git_commit_add_parent(commit, parent);
+
+	/* Set other attributes */
+	git_commit_set_committer(commit, &committer);
+	git_commit_set_author(commit, &author);
+	git_commit_set_message(commit, 
+			"This commit has been created in memory\n\
+This is a commit created in memory and it will be written back to disk\n");
+	
+	/* add new tree */
+	git_oid_mkstr(&id, tree_oid);
+	tree = git_tree_lookup(repo, &id);
+	must_be_true(tree != NULL);
+
+	git_commit_set_tree(commit, tree);
+
+	/* Test it has no OID */
+	must_be_true(git_commit_id(commit) == NULL);
+
+	/* Write to disk */
+	must_pass(git_object_write((git_object *)commit));
+
+	/* Show new SHA1 */
+/*
+	git_oid_fmt(hex_oid, git_commit_id(commit));
+	hex_oid[40] = 0;
+	printf("Written new commit, SHA1: %s\n", hex_oid);
+*/
+
+	must_pass(remove_loose_object(odb_dir, (git_object *)commit));
+
+	git_repository_free(repo);
+	git_odb_close(db);
+
+END_TEST
+
+BEGIN_TEST(writeback_test)
+	git_odb *db;
+	git_repository *repo;
+	git_oid id;
+	git_commit *commit, *parent;
+	const char *message;
+	/* char hex_oid[41]; */
+
+	must_pass(git_odb_open(&db, odb_dir));
+
+	repo = git_repository_alloc(db);
+	must_be_true(repo != NULL);
+
+	git_oid_mkstr(&id, commit_ids[0]);
+
+	commit = git_commit_lookup(repo, &id);
+	must_be_true(commit != NULL);
+
+	message = git_commit_message(commit);
+
+/*
+	git_oid_fmt(hex_oid, git_commit_id(commit));
+	hex_oid[40] = 0;
+	printf("Old SHA1: %s\n", hex_oid);
+*/
+
+	git_commit_set_message(commit, "This is a new test message. Cool!\n");
+
+	git_oid_mkstr(&id, commit_ids[4]);
+	parent = git_commit_lookup(repo, &id);
+	must_be_true(parent != NULL);
+
+	git_commit_add_parent(commit, parent);
+
+	must_pass(git_object_write((git_object *)commit));
+
+/*
+	git_oid_fmt(hex_oid, git_commit_id(commit));
+	hex_oid[40] = 0;
+	printf("New SHA1: %s\n", hex_oid);
+*/
+
+	must_pass(remove_loose_object(odb_dir, (git_object *)commit));
+
+	git_repository_free(repo);
+	git_odb_close(db);
+END_TEST
diff --git a/tests/t0802-write.c b/tests/t0802-write.c
new file mode 100644
index 0000000..4fc2621
--- /dev/null
+++ b/tests/t0802-write.c
@@ -0,0 +1,43 @@
+#include "test_lib.h"
+#include "test_helpers.h"
+#include "commit.h"
+
+#include <git/odb.h>
+#include <git/tag.h>
+#include <git/revwalk.h>
+
+static const char *odb_dir = "../resources/pack-odb";
+static const char *tag_id = "b25fa35b38051e4ae45d4222e795f9df2e43f1d1";
+
+BEGIN_TEST(tag_writeback_test)
+	git_odb *db;
+	git_oid id;
+	git_repository *repo;
+	git_tag *tag;
+	/* char hex_oid[41]; */
+
+	must_pass(git_odb_open(&db, odb_dir));
+
+	repo = git_repository_alloc(db);
+	must_be_true(repo != NULL);
+
+	git_oid_mkstr(&id, tag_id);
+
+	tag = git_tag_lookup(repo, &id);
+	must_be_true(tag != NULL);
+
+	git_tag_set_name(tag, "This is a different tag LOL");
+
+	must_pass(git_object_write((git_object *)tag));
+
+/*
+	git_oid_fmt(hex_oid, git_tag_id(tag));
+	hex_oid[40] = 0;
+	printf("TAG New SHA1: %s\n", hex_oid);
+*/
+
+	must_pass(remove_loose_object(odb_dir, (git_object *)tag));
+
+	git_repository_free(repo);
+	git_odb_close(db);
+END_TEST
diff --git a/tests/t0902-modify.c b/tests/t0902-modify.c
new file mode 100644
index 0000000..a321165
--- /dev/null
+++ b/tests/t0902-modify.c
@@ -0,0 +1,64 @@
+#include "test_lib.h"
+#include "test_helpers.h"
+#include "commit.h"
+
+#include <git/odb.h>
+#include <git/commit.h>
+#include <git/revwalk.h>
+
+static const char *odb_dir = "../resources/sample-odb";
+static const char *tree_oid = "1810dff58d8a660512d4832e740f692884338ccd";
+
+BEGIN_TEST(tree_add_entry_test)
+	git_odb *db;
+	git_oid id;
+	git_repository *repo;
+	git_tree *tree;
+	git_tree_entry *entry;
+	unsigned int i;
+	/* char hex_oid[41]; */
+
+	must_pass(git_odb_open(&db, odb_dir));
+
+	repo = git_repository_alloc(db);
+	must_be_true(repo != NULL);
+
+	git_oid_mkstr(&id, tree_oid);
+
+	tree = git_tree_lookup(repo, &id);
+	must_be_true(tree != NULL);
+
+	must_be_true(git_tree_entrycount(tree) == 3);
+
+	git_tree_add_entry(tree, &id, "zzz_test_entry.dat", 0);
+	git_tree_add_entry(tree, &id, "01_test_entry.txt", 0);
+
+	must_be_true(git_tree_entrycount(tree) == 5);
+
+	entry = git_tree_entry_byindex(tree, 0);
+	must_be_true(strcmp(git_tree_entry_name(entry), "01_test_entry.txt") == 0);
+
+	entry = git_tree_entry_byindex(tree, 4);
+	must_be_true(strcmp(git_tree_entry_name(entry), "zzz_test_entry.dat") == 0);
+
+	must_pass(git_tree_remove_entry_byname(tree, "README"));
+	must_be_true(git_tree_entrycount(tree) == 4);
+
+	for (i = 0; i < git_tree_entrycount(tree); ++i) {
+		entry = git_tree_entry_byindex(tree, i);
+		must_be_true(strcmp(git_tree_entry_name(entry), "README") != 0);
+	}
+
+	must_pass(git_object_write((git_object *)tree));
+
+/*
+	git_oid_fmt(hex_oid, git_tree_id(tree));
+	hex_oid[40] = 0;
+	printf("TREE New SHA1: %s\n", hex_oid);
+*/
+
+	must_pass(remove_loose_object(odb_dir, (git_object *)tree));
+
+	git_repository_free(repo);
+	git_odb_close(db);
+END_TEST
diff --git a/tests/test_helpers.c b/tests/test_helpers.c
index e7c2692..08434b8 100644
--- a/tests/test_helpers.c
+++ b/tests/test_helpers.c
@@ -26,6 +26,8 @@
 #include "common.h"
 #include "test_helpers.h"
 #include "fileops.h"
+#include "git/oid.h"
+#include "git/repository.h"
 
 int write_object_data(char *file, void *data, size_t len)
 {
@@ -82,6 +84,40 @@ int remove_object_files(const char *odb_dir, object_data *d)
 	return 0;
 }
 
+int remove_loose_object(const char *odb_dir, git_object *object)
+{
+	char *ptr, *full_path, *top_folder;
+	int path_length;
+
+	assert(odb_dir && object);
+
+	path_length = strlen(odb_dir);
+	ptr = full_path = git__malloc(path_length + GIT_OID_HEXSZ + 3);
+
+	strcpy(ptr, odb_dir);
+	ptr = top_folder = ptr + path_length;
+	*ptr++ = '/';
+	git_oid_pathfmt(ptr, git_object_id(object));
+	ptr += GIT_OID_HEXSZ + 1;
+	*ptr = 0;
+
+	if (gitfo_unlink(full_path) < 0) {
+		fprintf(stderr, "can't delete object file \"%s\"\n", full_path);
+		return -1;
+	}
+
+	*top_folder = 0;
+
+	if ((gitfo_rmdir(full_path) < 0) && (errno != ENOTEMPTY)) {
+		fprintf(stderr, "can't remove object directory \"%s\"\n", full_path);
+		return -1;
+	}
+
+	free(full_path);
+
+	return GIT_SUCCESS;
+}
+
 int cmp_objects(git_rawobj *o, object_data *d)
 {
 	if (o->type != git_obj_string_to_type(d->type))
diff --git a/tests/test_helpers.h b/tests/test_helpers.h
index 342a852..0d79d43 100644
--- a/tests/test_helpers.h
+++ b/tests/test_helpers.h
@@ -49,5 +49,7 @@ extern int remove_object_files(const char *odb_dir, object_data *d);
 
 extern int cmp_objects(git_rawobj *o, object_data *d);
 
+extern int remove_loose_object(const char *odb_dir, git_object *object);
+
 #endif
 /* INCLUDE_test_helpers_h__ */