Relates to unit testing and `Context` Hello there is there a

Question

Relates to unit testing and `Context` Hello there is there an equivalent of `build init resource context` for `StepExecutionContext` I m unit testing a custom IO Manager and getting an error when accessing ` context has partition key` InputContext It seems you can pass a `StepExecutionContext` to `build input context` but I m not sure how to instantiate that class

Chris Histe · Answer

```dagster core errors DagsterInvariantViolationError Attempting to access step context but it was not provided when constructing the InputContext``` The error

Chris Histe · Answer

The documentation says we should not instantiante `StepExecutionContext` so I assume there must a helper function for test

claire · Answer

Unfortunately there currently is not a helper function for fetching a `StepExecutionContext` The limitation here is that some information including the partition key is only available on the pipeline run object and this information is then passed to the `StepInputContext` Because a input context constructed via `build input context` is not associated with a pipeline run these fields cause an error

claire · Answer

Something you can do to test your IO manager is doing something like ```partitions def = StaticPartitionsDefinition a b c d class MyIOManager IOManager def handle output self context obj assert context asset partition key == b def load input self context asset partitions def=partitions def def my asset context assert context asset partitions def for output == partitions def my job = build assets job my job assets= my asset resource defs= io manager IOManagerDefinition hardcoded io manager MyIOManager result = my job execute in process partition key= b ```

Chris Histe · Answer

Hey Claire thanks Your example is similar to my code but I m trying to unit test my io manager not manually test it Are you suggesting I create an asset in my unit test

claire · Answer

You could create an ` asset` in each unit test or you could share the same ` asset` job across all unit tests and provide different partition keys depending your needs

Chris Histe · Answer

It s a bit weird to me to have an asset in my unit test I m trying to test my IO Manager It seems a bit overkill to update all my test to use an asset for one line of code Isn t there a better way to mock ` context has partition key`

claire · Answer

Hmm I realized we actually <https github com dagster io dagster blob d2caa5790aab98f8eeae428f04d7f00dfa4c087b python modules dagster dagster core execution context output py L806|allow for mocking the partition key on >`build output context` but not on `build input context` Maybe I can put together a PR quickly to allow for the same functionality on `build input context` slightly smiling face

claire · Answer

<https github com dagster io dagster pull 9836|This update> should make it out in next week s release 1 0 12

Chris Histe · Answer

Oh that s awesome thanks slightly smiling face

Chris Histe · Answer

I have a similar question could it be possible to configure the run id value in unit test through `build init resource context` I have `dagster run id = context run id` in my code and it s causing some errors because it s `None` during my unit test So as a workaround I m doing the folllowing but it s also a smell ``` if PYTEST CURRENT TEST in os environ dagster run id = unit testing else dagster run id = context run id```

claire · Answer

We don t currently have any functionality to do that but that seems like a reasonable request I can file an issue since it seems like there is an umbrella of configuration we d ideally like to be able to support for unit testing

Chris Histe · Answer

I would love that slightly smiling face

Chris Histe · Answer

Would it be possible get notified when and if that code is released

claire · Answer

I put out an issue here feel free to comment if you have any thoughts on other functionalities we should try to support <https github com dagster io dagster issues 9838>

claire · Answer

If you mean the pull request above that will be released next Thursday 10 6 If you mean additional functionalities for unit testing not sure it seems like we might need to think of higher level abstractions to make unit testing easier as a whole Though you can subscribe to the issue to follow any progress

Chris Histe · Answer

Alright thanks again slightly smiling face I will comment that issue

Chris Histe · Answer

It s always a delightful experience to talk to the Dagster team