diff --git a/git_commit_ai/tests/test_git_handler.py b/git_commit_ai/tests/test_git_handler.py
new file mode 100644
index 0000000..ee860ff
--- /dev/null
+++ b/git_commit_ai/tests/test_git_handler.py
@@ -0,0 +1,137 @@
+"""Tests for the Git handler module."""
+
+import os
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+from git.exc import GitCommandError
+
+from git_commit_ai.core.git_handler import GitHandler, GitError, get_git_handler
+
+
+class TestGitHandlerBasic:
+    """Basic Git handler tests."""
+
+    def test_is_repository_true(self, temp_git_repo):
+        """Test is_repository returns True for git repo."""
+        handler = GitHandler(str(temp_git_repo))
+        assert handler.is_repository() is True
+
+    def test_is_repository_false(self, tmp_path):
+        """Test is_repository returns False for non-git directory."""
+        handler = GitHandler(str(tmp_path))
+        assert handler.is_repository() is False
+
+
+class TestGitHandlerStagedChanges:
+    """Tests for staged changes functionality."""
+
+    def test_is_staged_true(self, temp_git_repo):
+        """Test is_staged returns True when changes are staged."""
+        handler = GitHandler(str(temp_git_repo))
+
+        test_file = temp_git_repo / "test.py"
+        test_file.write_text("print('test')")
+        os.system(f"git add {test_file}")
+
+        assert handler.is_staged() is True
+
+    def test_get_staged_changes(self, temp_git_repo):
+        """Test getting staged changes."""
+        handler = GitHandler(str(temp_git_repo))
+
+        test_file = temp_git_repo / "test.py"
+        test_file.write_text("print('test')")
+        os.system(f"git add {test_file}")
+
+        diff = handler.get_staged_changes()
+        assert diff != ""
+        assert "test.py" in diff
+
+
+class TestGitHandlerCommitHistory:
+    """Tests for commit history functionality."""
+
+    def test_get_commit_history(self, temp_git_repo):
+        """Test getting commit history."""
+        handler = GitHandler(str(temp_git_repo))
+        commits = handler.get_commit_history(max_commits=5)
+
+        assert len(commits) >= 1
+        assert any(c["message"] == "Initial commit" for c in commits)
+
+    def test_get_commit_history_conventional_only(self, temp_git_repo):
+        """Test getting only conventional commits."""
+        handler = GitHandler(str(temp_git_repo))
+        commits = handler.get_commit_history(max_commits=10, conventional_only=True)
+
+        for commit in commits:
+            assert commit["type"] != "unknown"
+
+
+class TestGitHandlerLanguageDetection:
+    """Tests for language detection functionality."""
+
+    def test_get_changed_languages_python(self, temp_git_repo):
+        """Test detecting Python files."""
+        handler = GitHandler(str(temp_git_repo))
+
+        test_file = temp_git_repo / "test.py"
+        test_file.write_text("print('hello')")
+        os.system(f"git add {test_file}")
+
+        languages = handler.get_changed_languages()
+        assert "Python" in languages
+
+    def test_get_changed_languages_multiple(self, temp_git_repo):
+        """Test detecting multiple languages."""
+        handler = GitHandler(str(temp_git_repo))
+
+        py_file = temp_git_repo / "test.py"
+        py_file.write_text("print('hello')")
+        js_file = temp_git_repo / "test.js"
+        js_file.write_text("console.log('hello')")
+
+        os.system(f"git add {py_file} {js_file}")
+
+        languages = handler.get_changed_languages()
+        assert "Python" in languages
+        assert "JavaScript" in languages
+
+
+class TestGitHandlerHelpers:
+    """Tests for helper methods."""
+
+    def test_get_staged_files(self, temp_git_repo):
+        """Test getting staged files list."""
+        handler = GitHandler(str(temp_git_repo))
+
+        test_file = temp_git_repo / "test.py"
+        test_file.write_text("print('test')")
+        os.system(f"git add {test_file}")
+
+        files = handler.get_staged_files()
+        assert "test.py" in [f for f in files if "test.py" in f]
+
+    def test_get_diff_summary(self, temp_git_repo):
+        """Test getting diff summary."""
+        handler = GitHandler(str(temp_git_repo))
+
+        test_file = temp_git_repo / "test.py"
+        test_file.write_text("print('test')")
+        os.system(f"git add {test_file}")
+
+        summary = handler.get_diff_summary()
+        assert "Files changed" in summary
+        assert "Python" in summary
+
+
+class TestGitError:
+    """Tests for GitError exception."""
+
+    def test_git_error_raised(self):
+        """Test GitError is raised on git errors."""
+        with pytest.raises(GitError):
+            handler = GitHandler("/nonexistent/path")
+            handler.repo