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# Test Client
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Flask test client fixtures for HTTP request testing. Provides access to Flask's built-in test client with automatic application context management and enhanced response handling.
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## Capabilities
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### Test Client Fixture
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Provides a Flask test client instance for making HTTP requests to the application during tests. The client is automatically configured with the test application and manages request contexts.
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```python { .api }
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@pytest.fixture
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def client(app):
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    """
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    A Flask test client. An instance of flask.testing.TestClient by default.
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    Parameters:
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        app: Flask application instance (from app fixture)
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    Returns:
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        TestClient: Flask test client configured for the application
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    """
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```
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**Usage Example:**
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```python
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def test_get_request(client):
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    response = client.get('/api/users')
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    assert response.status_code == 200
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def test_post_request(client):
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    data = {'name': 'John', 'email': 'john@example.com'}
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    response = client.post('/api/users', json=data)
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    assert response.status_code == 201
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    assert response.json['id'] is not None
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def test_with_headers(client):
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    headers = {'Authorization': 'Bearer token123'}
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    response = client.get('/api/protected', headers=headers)
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    assert response.status_code == 200
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```
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### Class-Based Test Client
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Sets the test client as a class attribute for test classes, enabling shared client access across test methods within a class.
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```python { .api }
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@pytest.fixture
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def client_class(request, client):
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    """
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    Uses to set a ``client`` class attribute to current Flask test client.
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    Parameters:
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        request: pytest request object
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        client: Flask test client instance
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    Returns:
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        None (sets client attribute on test class)
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    """
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```
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### MIME Type Parameter Fixture
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Provides parametrized MIME types for testing content negotiation. This is used internally by `accept_mimetype` but can be used independently.
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```python { .api }
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@pytest.fixture(params=["application/json", "text/html"])
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def mimetype(request):
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    """
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    Parametrized fixture providing common MIME types.
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    Parameters:
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        request.param: One of "application/json" or "text/html"
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    Returns:
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        str: MIME type string for the current test parameter
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    """
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```
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**Usage Example:**
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```python
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def test_content_type_handling(client, mimetype):
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    """Test endpoint handles different MIME types"""
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    headers = [("Content-Type", mimetype)]
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    data = {'test': 'data'} if mimetype == 'application/json' else 'test=data'
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    response = client.post('/api/data', 
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                          data=data if mimetype != 'application/json' else None,
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                          json=data if mimetype == 'application/json' else None,
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                          headers=headers)
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    assert response.status_code == 200
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```
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**Usage Example:**
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```python
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@pytest.mark.usefixtures('client_class')
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class TestUserAPI:
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    def login(self, email, password):
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        """Helper method using self.client"""
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        credentials = {'email': email, 'password': password}
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        return self.client.post('/auth/login', json=credentials)
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    def test_user_login(self):
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        response = self.login('user@example.com', 'password123')
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        assert response.status_code == 200
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        assert 'token' in response.json
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    def test_protected_route(self):
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        # Login first
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        login_response = self.login('user@example.com', 'password123')
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        token = login_response.json['token']
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        # Access protected route
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        headers = {'Authorization': f'Bearer {token}'}
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        response = self.client.get('/api/profile', headers=headers)
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        assert response.status_code == 200
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```
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## Enhanced Response Features
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The test client automatically provides enhanced response objects with additional JSON testing capabilities:
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### JSON Response Comparison
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Response objects can be compared directly with HTTP status codes and include automatic JSON parsing:
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```python
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def test_json_response(client):
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    response = client.get('/api/ping')
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    # Status code comparison
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    assert response == 200
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    # JSON content access
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    assert response.json == {'ping': 'pong'}
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    # Traditional status code access still works
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    assert response.status_code == 200
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    assert response.status == '200 OK'
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```
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### Automatic Request Context
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The test client automatically pushes Flask request contexts during tests, enabling use of Flask utilities:
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```python
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from flask import url_for
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def test_with_url_for(client):
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    # url_for works automatically in tests
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    response = client.get(url_for('api.get_user', user_id=123))
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    assert response.status_code == 200
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def test_reverse_url(client):
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    # Can build URLs using Flask's routing
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    url = url_for('api.create_user')
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    response = client.post(url, json={'name': 'Jane'})
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    assert response.status_code == 201
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```