diff --git a/tests/test_ollama_client.py b/tests/test_ollama_client.py
new file mode 100644
index 0000000..11720ad
--- /dev/null
+++ b/tests/test_ollama_client.py
@@ -0,0 +1,141 @@
+"""Tests for ollama_client.py."""
+
+from unittest.mock import Mock, patch, MagicMock
+
+import pytest
+
+from src.ollama_client import (
+    OllamaClient,
+    OllamaError,
+    OllamaConnectionError,
+    OllamaModelNotFoundError,
+    OllamaModel,
+)
+from src.config import Config
+
+
+class TestOllamaClient:
+    """Tests for OllamaClient class."""
+
+    @pytest.fixture
+    def mock_client(self):
+        """Create a mock Ollama client."""
+        with patch("src.ollama_client.ollama.Client") as mock:
+            yield mock
+
+    @pytest.fixture
+    def config(self):
+        """Create a test configuration."""
+        return Config(
+            ollama_host="http://localhost:11434",
+            model="llama3.2",
+        )
+
+    @pytest.fixture
+    def ollama_client(self, config, mock_client):
+        """Create an OllamaClient with mocked dependencies."""
+        client = OllamaClient(config)
+        return client
+
+    def test_client_initialization(self, config):
+        """Test client initialization."""
+        client = OllamaClient(config)
+        assert client.config.ollama_host == "http://localhost:11434"
+        assert client.config.model == "llama3.2"
+
+    def test_connect_with_retry_success(self, ollama_client, mock_client):
+        """Test successful connection with retry."""
+        mock_response = Mock()
+        mock_response.models = []
+        mock_client.return_value.ps.return_value = mock_response
+
+        result = ollama_client.connect_with_retry(max_retries=1)
+        assert result is True
+
+    def test_connect_with_retry_failure(self, ollama_client, mock_client):
+        """Test failed connection with retry."""
+        import ollama
+        mock_client.return_value.ps.side_effect = ollama.RequestError("Connection refused")
+
+        with pytest.raises(OllamaConnectionError):
+            ollama_client.connect_with_retry(max_retries=1)
+
+    def test_list_models(self, ollama_client, mock_client):
+        """Test listing available models."""
+        mock_model = Mock()
+        mock_model.name = "llama3.2"
+        mock_model.size = 4000000000
+        mock_model.digest = "abc123"
+        mock_model.modified_at = "2024-01-15T10:00:00"
+
+        mock_response = Mock()
+        mock_response.models = [mock_model]
+        mock_client.return_value.ps.return_value = mock_response
+
+        models = ollama_client.list_models()
+        assert len(models) == 1
+        assert models[0].name == "llama3.2"
+
+    def test_generate_commit_message(self, ollama_client, mock_client):
+        """Test generating a commit message."""
+        mock_response = Mock()
+        mock_response.message.content = "feat(api): add new endpoint"
+        mock_client.return_value.chat.return_value = mock_response
+
+        result = ollama_client.generate_commit_message("some diff content")
+        assert result == "feat(api): add new endpoint"
+
+    def test_generate_commit_message_with_language(self, ollama_client, mock_client):
+        """Test generating a commit message with language context."""
+        mock automated testing
+        mock_response = Mock()
+        mock_response.message.content = "feat(python): add helper function"
+        mock_client.return_value.chat.return_value = mock_response
+
+        result = ollama_client.generate_commit_message("diff content", language="python")
+        assert "python" in str(mock_client.return_value.chat.call_args)
+
+    def test_generate_changelog(self, ollama_client, mock_client):
+        """Test generating a changelog."""
+        mock_response = Mock()
+        mock_response.message.content = "# Changelog\n\n## Features\n- New feature added"
+        mock_client.return_value.chat.return_value = mock_response
+
+        commits = [
+            {"sha": "abc123", "message": "feat: new feature", "author": "Test User"}
+        ]
+        result = ollama_client.generate_changelog(commits)
+        assert "Changelog" in result
+
+    def test_generate_api_docs(self, ollama_client, mock_client):
+        """Test generating API documentation."""
+        mock_response = Mock()
+        mock_response.message.content = "# API Documentation\n\n## GET /users\nReturns list of users"
+        mock_client.return_value.chat.return_value = mock_response
+
+        code_changes = {"src/api.py": "some diff content"}
+        result = ollama_client.generate_api_docs(code_changes)
+        assert "API Documentation" in result
+
+    def test_model_not_found_error(self, ollama_client, mock_client):
+        """Test handling model not found error."""
+        import ollama
+        mock_client.return_value.chat.side_effect = ollama.ResponseError("model not found")
+
+        with pytest.raises(OllamaModelNotFoundError):
+            ollama_client.generate_commit_message("diff content")
+
+
+class TestOllamaModel:
+    """Tests for OllamaModel dataclass."""
+
+    def test_ollama_model_creation(self):
+        """Test creating an OllamaModel object."""
+        model = OllamaModel(
+            name="llama3.2",
+            size=4000000000,
+            digest="abc123",
+            modified_at="2024-01-15T10:00:00",
+        )
+        assert model.name == "llama3.2"
+        assert model.size == 4000000000