The cloud-native orchestrator for the whole development lifecycle, with integrated lineage and observability.

dagster

I’ve found that testing is generally pretty great in Dagster. Testing ops, jobs, and assets all works really well. Using the new `<http://asset.to|asset.to>_source_asset()`  in jobs doesn’t have a great story for testing yet though. I think what I’d like is a testing utility that’s something like “Pretend that my_cool_asset was materialized with this_particular_value”, maybe a context manager for that.

Here’s my job:
```def my_job():
    asset_val = upstream_asset.to_source_asset()
    op1_result = op1()
    op2_result = op2(asset_val, op1_result)
    op3(op2_result)```

I might try to do something like
```def test_my_job():
    with unittest.mock.patch("path.to.upstream_asset.to_source_asset") as mock_to_source_asset:
        mock_to_source_asset.return_val = "foo"
        ...
        my_job.execute_in_process()```
but I’m not sure this will work?

Maybe I could `materialize_in_memory` my asset, but my `upstream_asset` is pretty complicated here

Would something like this help? <https://github.com/dagster-io/dagster/issues/7656>