PyTest

我啥时候遇到的¶

在写03-Backend时，需要加unit test
Unit testing is about testing the smallest “units” of your code, like a single function or endpoint, to make sure they behave correctly in isolation.
We want to test:
1. What happens if no file is uploaded?
2. What if the file is uploaded but has no name?
3. What happens when a valid image is sent?

用法¶

How pytest Works With Flask¶

Flask provides a test client. It lets you: - Call routes without running a real server. - Simulate requests (GET, POST, etc.). - Check responses.

Example: response = client.post('/run-detect')

fixture¶

@pytest.fixture
%% 表示下面这个函数是个 fixture。pytest 会在测试里识别它。 %%

def client(): %% 定义了一个名字叫 `client` 的 fixture。 %%
    app = create_app()
    app.config['TESTING'] = True
    return app.test_client()

以上是固定写法，因为Flask 的单元测试都要用 test_client()，所以大家都用 fixture 来统一创建 client，省得每个测试都重复写。
fixture: pytest 提供的一种测试前准备或资源管理的机制，可以：建立数据库连接，创建 Flask 测试客户端，准备测试数据
fixture 写好后，在你的测试函数里直接作为参数使用。比如：
```
def test_run_detect_no_file(client):
    ...
```
这里的 client 就是 pytest 自动注入你定义好的 fixture。

具体tests写法¶

def test_run_detect_success(client):
    """Test successful detection with a sample image"""
    TEST_DIR = os.path.dirname(os.path.abspath(__file__))
    test_img1 = os.path.join(TEST_DIR, 'test_img1.jpeg')

    with open(test_img1, 'rb') as img:
        data = {'file': (img, 'test_img1.jpeg')}
        response = client.post('/run-detect', 
                                data=data,
                                content_type='multipart/form-data')

    assert response.status_code == 200
    data = json.loads(response.data)
    assert 'boxes' in data
    assert isinstance(data['boxes'], list)
    assert len(data['boxes']) > 0 # At least one detection

    box = data['boxes'][0]
    assert 'label' in box
    assert 'confidence' in box
    assert 'x' in box
    assert 'y' in box
    assert 'width' in box
    assert 'height' in box

在原来的file中需要加这一行：os.environ['TORCH_FORCE_NO_WEIGHTS_ONLY_LOAD'] = '1'

如何run tests¶

安装pytest
```
pip3 install pytest
```
或者写在你的 requirements.txt 里加上pytest，然后：
```
pip3 install -r requirements.txt
```
运行pytest

重点： - 测试文件在 tests/ 下 - 测试文件名是 test_xxx.py（pytest 默认会识别）

python3 -m pytest tests/test_routes.py -v