How to disable Prefect logger for tests?

Question

In prefect 2 how can I test a flow or task which is using the ```get run logger ``` which is set from the context You can find sample test code on the thread The test keep failing with the erorr ```prefect exceptions MissingContextError There is no active flow or task run context ```

davzucky · Answer

```import pytest from prefect import flow task get run logger from prefect testing utilities import prefect test harness pytest fixture autouse=True scope= session def prefect test fixture with prefect test harness yield task def sum a int b int gt int return a + b task def sum with logger a int b int gt int logger = get run logger logger debug f sum a + b = a+b return a + b flow def sum flow with logger a int b int gt int return sum with logger a b def test sum Test pass a = 1 b = 3 result = sum fn a b assert 4 == result def test sum with logger test error with prefect exceptions MissingContextError There is no active flow or task run context a = 1 b = 3 result = sum with logger fn a b assert 4 == result def test sum flow with logger test error with prefect exceptions MissingContextError There is no active flow or task run context a = 1 b = 3 result = sum flow with logger fn a b assert 4 == result```

Peyton Runyan · Answer

I don t actually know the pattern that we encourage for this but I would personally just mock and monkeypatch If we have a file `ex py` which has our example flow ```from prefect import flow get run logger flow def my flow get run logger info I am logging stuff return 42``` and we have our test file `test ex py` I would probably do something similar to the following ```from unittest mock import Mock from ex import my flow def test my flow monkeypatch mock logger = Mock monkeypatch setattr ex get run logger mock logger res = my flow ```

Peyton Runyan · Answer

You could also accomplish this with a fixture

Peyton Runyan · Answer

```from unittest mock import Mock from ex import my flow import pytest pytest fixture def mock logger monkeypatch mock logger = Mock monkeypatch setattr ex get run logger mock logger return mock logger def test my flow mock logger res = my flow ```

davzucky · Answer

Try indeed Good point +1 about the mocking in prefect 1 they use to have an helper that unit the context

davzucky · Answer

What other pattern would you use

Peyton Runyan · Answer

Hmmm give me just a moment

Krishnan Chandra · Answer

Here s the workaround that we use in `conftest py` ```from prefect logging import disable run logger from prefect testing utilities import prefect test harness pytest fixture autouse=True scope= session def prefect disable logging with disable run logger yield pytest fixture autouse=True scope= session def prefect test fixture with prefect test harness yield```

Krishnan Chandra · Answer

This will disable the logger in your tests not useful if you want to test the logging itself but helpful if you don t need to

Peyton Runyan · Answer

Yeah if you aren t worried about the output that s a great way to go too

davzucky · Answer

thank you < Krishnan Chandra> This is working perfectly

davzucky · Answer

as I m interesting about the logic of the task that I want to test

davzucky · Answer

Thank you < Peyton Runyan> for pointing me to the mock Completly discarded this option

davzucky · Answer

Have a good Thanksgiving guys if you are in US

davzucky · Answer

should ```disable run logger``` not be in ```prefect testing utilities``` be a better place as I don t know when you would use it outside of testing

Anna Geller · Answer

true it could be but you can use it not only in unit tests e g I can imagine someone may want to disable it for a local run not a unit test