使用 pytest-xdist 跨主节点和工作节点访问共享资源

Question

我正在尝试在主节点和工作节点之间共享数据库中的随机条目列表(我对共享资源的定义(，并使用pytest-xdist并行化测试。我的代码遵循以下结构：

## in conftest.py
def get_db_entries():
connect to db
run a query with group by and random
returns one random entry per group as a list of dictionaries.

我调整了 https://hackebrot.github.io/pytest-tricks/shared_directory_xdist/提供的建议，以便在主节点和工作节点之间共享数据库条目：

# in conftest.py
def pytest_configure(config):
if is_master(config):
# share db_entries across master and worker nodes.
config.db_samples = get_db_entries()
def pytest_configure_node(node):
"""xdist hook"""
node.slaveinput['db_entries'] = node.config.db_samples
def is_master(config):
"""True if the code running the given pytest.config object is running in a xdist master
node or not running xdist at all.
"""
return not hasattr(config, 'slaveinput')
@pytest.fixture
def db_samples(request):
"""Returns a unique and temporary directory which can be shared by
master or worker nodes in xdist runs.
"""
if is_master(request.config):
return request.config.db_samples
else:
return request.config.slaveinput['db_entries']

我能够使用上述方法在主节点和辅助节点之间共享这些数据库条目，如下所示：

# in test-db.py
def test_db(db_samples):
for sample in samples:
# test each sample.

到目前为止，还没有测试用例的并行化。我只是在主节点和工作节点之间共享相同的数据库条目。

我的问题：如何参数化共享资源状态(数据库条目(，以便可以使用pytest-xdist并行执行这些测试？

我想做一些类似的事情：

# in conftest.py
samples = db_samples() # will FAIL coz fixture can't be invoked directly.
@pytest.fixture(params=samples)
def get_sample(request):
return request.param
# in test-db.py
def test_db(get_sample):
# test one sample.

Answer 1

感谢@hoefling的建议，我能够使用pytest-xdist钩子和pytest_generate_tests来获得有效的解决方案。

# in conftest.py
def pytest_configure(config):
if is_master(config):
# share db_entries across master and worker nodes.
config.db_samples = get_db_entries()
def pytest_configure_node(node):
"""xdist hook"""
node.slaveinput['db_entries'] = node.config.db_samples
def is_master(config):
"""True if the code running the given pytest.config object is running in a xdist master
node or not running xdist at all.
"""
return not hasattr(config, 'slaveinput')
def pytest_generate_tests(metafunc):
if 'sample' in metafunc.fixturenames:
if is_master(metafunc.config):
samples = metafunc.config.db_samples
else:
samples = metafunc.config.slaveinput['db_entries']
metafunc.parametrize("sample", samples)
@pytest.fixture
def sample(request):
return request.param
# in test-db.py
def test_db(sample):
# test one sample.

@hoefling建议使用pytest_generate_tests钩子是缺失的部分。使用此钩子对测试夹具进行参数化有助于解决此问题。