Graciously handling DAP failure on multistep (build then run) languages

[fnzr]

Hello!
I'm working on improving the DAP handling on the zig adapter, and we are exploring how to handle build errors.

When running tests with integrated strategy, we have a nice feedback on compile errors:

We are now trying to figure out how to do something similar when using the dap strategy.

Languages that require building before running tests can fail in either step, and when using the dap strategy, I don't see any way to gracefully handle it: the the debugger is always launched in a invalid state.

This is not a zig specific issue, it happens with the golang adapter:

The rust adapter does its best to identify and report build errors, but can't do anything about it, and the debugger is also launched in an invalid state:

As I understand it, there's nothing the adapter can do about this problem. The dap strategy expects a dap configuration, and not providing it results in either a "adapter doesn't support the dap strategy" message, some cryptic configuration error, or launching the debugger in a bad state, because the strategy handler either expects nothing, or just launches.

(here)

neotest/lua/neotest/client/strategies/dap/init.lua

Line 27 in 6f35d79

return function(spec, context)

It would be nice if the adapters could somehow report to the strategy handler that "hey, something bad happened, do not launch the debugger"

Does this feature exists (maybe I'm just missing it)? If not, would it be doable?

[fnzr]

moved to issue #415