Make configuration error message when debugging Python tests more helpful

[scottshambaugh]

Requesting to reopen #17150. The issue is still present in v2022.4.1, and as the ticket is locked I cannot comment on it directly.

[karthiknadig]

Scott Shambaugh (@scottshambaugh) Can you elaborate? if you have "request": "test" only then you will see the message:

'This configuration can only be used by the test debugging commands. `"request": "test"` is deprecated use "purpose" instead.'

[karthiknadig]

When creating the default configuration use this template:

{
            "name": "Debug Tests",
            "type": "python",
            "request": "launch",
            "purpose": ["debug-test"],
            "justMyCode": true
}

[scottshambaugh]

Yes I've been able to figure out what I should be using. My request is the exact same as the linked issue, ie that the error message be changed to something more helpful:

I don't mind changing my launch.json file. However, in order to comply with the error message and "use 'purpose' instead," I need to know the precise syntax to use. The phrase "use purpose" doesn't tell me if that should be the key or the value in the json - should it be "purpose": "test" or should it be "request": "purpose"? Actually, neither one of these work. Both throw an error.

Is this new syntax ("purpose": ["debug-test"]) documented somewhere? That was the big issue for me...the error message told me I had something misconfigured but did not let me know what the valid options are, or point me to some documentation where the new options are listed.

So instead of the error message being "This configuration can only be used by the test debugging commands. '"request": "test"' is deprecated use "purpose" instead.", I would ask that it be changed to something like "This configuration can only be used by the test debugging commands. '"request": "test"' is deprecated, please keep as "request": "launch" and add "purpose": ["debug-test"] instead."