diff --git a/app/tests/test_git_utils.py b/app/tests/test_git_utils.py
new file mode 100644
index 0000000..a1f2923
--- /dev/null
+++ b/app/tests/test_git_utils.py
@@ -0,0 +1,138 @@
+"""Tests for git_utils.py."""
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from git_commit_generator.git_utils import GitUtils
+
+
+class TestGitUtils:
+    """Test cases for GitUtils."""
+
+    @pytest.fixture
+    def git_utils(self):
+        """Create a GitUtils instance with mocked repository."""
+        with patch("git_commit_generator.git_utils.Repo") as mock_repo:
+            repo = MagicMock()
+            mock_repo.return_value = repo
+            utils = GitUtils("/fake/path")
+            utils.repo = repo
+            yield utils
+
+    def test_is_repo_true(self, git_utils):
+        """Test is_repo returns True for valid repository."""
+        git_utils.repo.bare = False
+        result = git_utils.is_repo()
+        assert result is True
+
+    def test_is_repo_false(self, git_utils):
+        """Test is_repo returns False for invalid repository."""
+        git_utils.repo.bare = True
+        result = git_utils.is_repo()
+        assert result is False
+
+    def test_get_staged_diff(self, git_utils):
+        """Test getting staged diff."""
+        diff_mock = MagicMock()
+        diff_mock.diff = b"diff --git a/file.py b/file.py"
+        git_utils.repo.index.diff.return_value = [diff_mock]
+
+        result = git_utils.get_staged_diff()
+
+        assert "diff --git a/file.py b/file.py" in result
+
+    def test_get_unstaged_diff(self, git_utils):
+        """Test getting unstaged diff."""
+        diff_mock = MagicMock()
+        diff_mock.diff = "diff --git a/file.py b/file.py"
+        git_utils.repo.index.diff.return_value = [diff_mock]
+
+        result = git_utils.get_unstaged_diff()
+
+        assert "diff --git a/file.py b/file.py" in result
+
+    def test_get_staged_files(self, git_utils):
+        """Test getting list of staged files."""
+        diff_mock = MagicMock()
+        diff_mock.a_path = "src/main.py"
+        git_utils.repo.index.diff.return_value = [diff_mock]
+
+        result = git_utils.get_staged_files()
+
+        assert result == ["src/main.py"]
+
+    def test_get_commit_history(self, git_utils):
+        """Test getting commit history."""
+        commit_mock = MagicMock()
+        commit_mock.hexsha = "abc1234567890"
+        commit_mock.message = "feat: add new feature"
+        commit_mock.author.name = "Test User"
+        commit_mock.author.email = "test@example.com"
+        commit_mock.committed_datetime.isoformat.return_value = "2024-01-15T10:30:00"
+
+        git_utils.repo.iter_commits.return_value = [commit_mock]
+
+        result = git_utils.get_commit_history(limit=10)
+
+        assert len(result) == 1
+        assert result[0]["hash"] == "abc1234"
+        assert result[0]["full_hash"] == "abc1234567890"
+        assert result[0]["message"] == "feat: add new feature"
+
+    def test_get_conventional_commits(self, git_utils):
+        """Test filtering conventional commits."""
+        commit_mock = MagicMock()
+        commit_mock.hexsha = "abc1234567890"
+        commit_mock.message = "feat(api): new feature"
+        commit_mock.author.name = "Test User"
+        commit_mock.author.email = "test@example.com"
+        commit_mock.committed_datetime.isoformat.return_value = "2024-01-15T10:30:00"
+
+        git_utils.repo.iter_commits.return_value = [commit_mock]
+
+        result = git_utils.get_conventional_commits()
+
+        assert len(result) == 1
+        assert result[0]["type"] == "feat"
+        assert result[0]["scope"] == "api"
+
+    def test_get_file_scopes(self, git_utils):
+        """Test extracting scopes from file paths."""
+        git_utils.get_changed_files = MagicMock(return_value=[
+            "api/routes.py",
+            "auth/login.py",
+            "tests/test_main.py",
+        ])
+
+        result = git_utils.get_file_scopes()
+
+        assert "api" in result
+        assert "auth" in result
+
+    def test_is_conventional_message_valid(self, git_utils):
+        """Test conventional message validation."""
+        message = "feat(auth): add login functionality"
+        result = git_utils._is_conventional_message(message)
+        assert result is True
+
+    def test_is_conventional_message_invalid(self, git_utils):
+        """Test non-conventional message validation."""
+        message = "Added new feature"
+        result = git_utils._is_conventional_message(message)
+        assert result is False
+
+    def test_parse_conventional_commit_full(self, git_utils):
+        """Test parsing full conventional commit."""
+        message = "fix(database): resolve connection timeout issue"
+        result = git_utils._parse_conventional_commit(message)
+        assert result["type"] == "fix"
+        assert result["scope"] == "database"
+        assert result["description"] == "resolve connection timeout issue"
+
+    def test_parse_conventional_commit_no_scope(self, git_utils):
+        """Test parsing conventional commit without scope."""
+        message = "chore: update dependencies"
+        result = git_utils._parse_conventional_commit(message)
+        assert result["type"] == "chore"
+        assert result["scope"] == ""
+        assert result["description"] == "update dependencies"