v2-only mode should not acknowledge v1 goals

[benjyw]

Previously all v1 goals were included when validating
the requested goals, even with --no-v1.

This change:

1. Only accepts requests for v2 goals if --no-v1 --v2 is set.
2. Only lists v2 goals for ./pants list, if --no-v1 --v2 is set.

This leads to a more isolated "v2-only" experience.

[stuhood]

@benjyw : I haven't given much thought to how we (Twitter, but any other company with a mixed repository) will migrate across the "python is v2, everything else is v1" boundary... it would be good to do that before continuing to tweak these options, as they were implemented a while back when that question was much more hypothetical than it is now.

[benjyw]

@benjyw : I haven't given much thought to how we (Twitter, but any other company with a mixed repository) will migrate across the "python is v2, everything else is v1" boundary... it would be good to do that before continuing to tweak these options, as they were implemented a while back when that question was much more hypothetical than it is now.

Well, this should only affect things when turning v1 off entirely (--no-v1), which I guess is not the case if you have a mixed repo?

But I think that --no-v1 really should turn off the v1 engine as much as possible.

[stuhood]

We have all day meetings today, so had only a few minutes to think about this, but here are some notes:

Imagining a period where JVM and JS are v1, but Python has been ported to v2:

• --v1 --v2 : will run everything
• --no-v1 --v2: will run only Python tests
• --v1 --no-v2: will run everything but Python tests

In the current state, when Python has been "partially ported": how does v2 "become the default" for Python?

• Cannot globally set --v1 --v2, because would cause tests to double-run in v1 and v2 test
• Would need to ask beta python users Python users to pass --no-v1 --v2 to all commands...?
  • Cannot make this the default for the repo, because would break JVM/JS users

So... it feels like these flags need to somehow become language or backend-aware, rather than being global.

[benjyw]

On Tue, Oct 22, 2019 at 1:02 PM Stu Hood ***@***.***> wrote: We have all day meetings today, so had only a few minutes to think about this, but here are some notes: Imagining a period where JVM and JS are v1, but Python has been ported to v2: - --v1 --v2 : will run everything - --no-v1 --v2: will run only Python tests - --v1 --no-v2: will run everything but Python tests In the current state, when Python has been "partially ported": how does v2 "become the default" for Python? - Cannot globally set --v1 --v2, because would cause tests to double-run in v1 and v2 test - Would need to ask beta python users Python users to pass --no-v1 --v2 to all commands...? - Cannot make this the default for the repo, because would break JVM/JS users So... it feels like these flags need to somehow become language or backend-aware, rather than being global.

Or, I'm fine with some other solution (a --v2-only option?) but I do want to provide a completely v2-only experience one way or another.

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[benjyw]

On Tue, Oct 22, 2019 at 1:02 PM Stu Hood @.***> wrote: - Cannot globally set --v1 --v2, because would cause tests to double-run in v1 and v2 test

Why would we keep the v1 python test task around though?

This change makes the --v1 --v2 flags live up to their descriptions:

    # Toggles v1/v2 `Task` vs `@rule` pipelines on/off.
    register('--v1', advanced=True, type=bool, default=True,
             help='Enables execution of v1 Tasks.')
    register('--v2', advanced=True, type=bool, default=False,
             help='Enables execution of v2 @console_rules.')

[stuhood]

Why would we keep the v1 python test task around though?

We'll need to until it's feature complete, and/or until we've deprecated the relevant flags on test.pytest.

This change makes the --v1 --v2 flags live up to their descriptions:

From that perspective, I'm fine with it. I'm just pointing out that this will not be sufficient to accomplish a migration from v1 to v2, in general: the flags will need further changes.

It doesn't seem to make things any harder though, so I won't block it.

[stuhood]

Opened #8550 about that followup.