til/pytest/only-run-integration.md
# Opt-in integration tests with pytest --integration
For both [s3-credentials](https://github.com/simonw/s3-credentials) and [datasette-publish-fly](https://github.com/simonw/datasette-publish-fly) I have a need for real-world integration tests that actually interact with the underlying APIs (AWS or Fly) to create and destroy resources on those platforms.
Most of the time I want my tests to run without doing these. I want the option to run `pytest --integration` to opt-in to running those extra integration tests.
Here's the pattern I'm using. First, in `tests/conftest.py`:
```python
import pytest
def pytest_addoption(parser):
parser.addoption(
"--integration",
action="store_true",
default=False,
help="run integration tests",
)
def pytest_configure(config):
config.addinivalue_line(
"markers",
"integration: mark test as integration test, only run with --integration",
)
def pytest_collection_modifyitems(config, items):
if config.getoption("--integration"):
# Also run integration tests
return
skip_integration = pytest.mark.skip(reason="use --integration option to run")
for item in items:
if "integration" in item.keywords:
item.add_marker(skip_integration)
```
This implements a `@pytest.mark.integration` marker which I can use to mark any test that should be considered part of the integration test suite. These will be skipped by default... but will not be skipped if the `--integration` option is passed to `pytest`.
Then in the tests I can either do this:
```python
@pytest.mark.integration
def test_integration_s3():
# ...
```
Or if I have a module that only contains integration tests - `tests/test_integration.py` - I can use the following line to apply that decorator to every test in the module:
```python
import pytest
pytestmark = pytest.mark.integration
def test_integration_s3():
# ...
```