fix: clear target test runner state after each run

[pnadolny13]

The target test framework had weird behavior where all 14 default tests passed for me but when I looked closer only 1 table was getting created in the destination database. I figured out it was because the input file was getting stuck on the first test's input file.

The test overrides the runner input_filepath

sdk/singer_sdk/testing/templates.py

Line 325 in fda24cf

runner.input_filepath = self.singer_filepath

to pass in the path to the test's JSONL data but it only gets used on the first test because the second test uses the runner while it still has self._input state from the previous run so it skips the logic for reading in the new file. Ultimately all following tests get no input so they silently pass but dont actually do anything.

I confirmed this fix worked in MeltanoLabs/target-snowflake#38.

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📚 Documentation preview 📚: https://meltano-sdk--1749.org.readthedocs.build/en/1749/

[kgpayne]

@pnadolny13 @edgarrmondragon I think the issue and fix is a bit broader than resetting the target_input (though that obviously works).

A reset is needed because we made the runner instance a pytest fixture with scope="class". This is desirable for Taps as it means they can run once (to hydrate the runners record/state/messages attributes) and then run multiple tests on the same record set. It was done to minimise the number of times the Taps actually has to run. However, with Target tests and especially with the file-based ones, we actually want to allow the Target to sync multiple times with the different file inputs. So I believe the change needed is to set the runner scope to function when constructing Target classes 🙂 This has a similar effect to resetting the runners input as each runner is 'fresh' and so doesn't have any previous state.

Will raise a PR in target-snowflake to test the fix.

[kgpayne]

Related to #1752

[pnadolny13]

Closing in favor of #1752 and I also found another bug for tests that follow a pytest.raises( we weren't getting a reset, I fixed that in target-snowflake for now though.