Prompt the user for the startup script when pressing F5 on a Dart project (rather than opening launch.json)

Flutter works better now (no launch.json needed, just press F5) but with Dart we need to know which script to use.

I suggest when we don’t have a program we either open a file open dialog or give the user a pick list of all .dart files inside the bin, test and tools folders to pick from (@devoncarew, @mit-mit any preferences?) and then ensure this gets stashed into launch.json so they don’t have to do it on every F5.

If the current open file is already inside bin/test/tool maybe we should just assume it and skip the prompt.

[DanTup]

@pulyaevskiy FYI - it’s not a complete solution for this, but #1206 adds a “Dart: Rerun Last Debug Session” command (bound to Cmd+Shift+F5/Ctrl+Shift+F5 when not already debugging) which might help a little. It re-runs the last debug session, with ${file} etc. having been resolved.

So, if you have ${file} (or nothing) in your launch.json such that F5 runs the open file, then you switch to another file and run this command, it’ll re-run the same file as original. This also means if you click a Run/Debug Codelens link then end up jumping into the code being tested, you can re-run the same test (or group, or file, or whatever) from wherever you are without switching back to the test file.

[DanTup]

v2.11 Beta 2 has some additional changes that solves some (but not all) of the things in here. If you have no launch.json and hit F5 then your current file will be invoked if it’s inside test/bin/tool.

Thoughts for improving this are detecting if the script has a main method in it and if not, prompt the user:

The current file cannot be executed, would you like to run the last run script? [ Run bin/main.dart ] [ Create launch.json ]

bin/main.dart would be replaced with the last file that was run. We can add a setting to “always run the last run script if the current file is not executable” which you can set globally, or at workspace level. It would function the same as clicking the left button on the prompt above. If there is no last run script we’ll still show a prompt, but change the text somehow (maybe take a guess at the script to run) - I don’t want to just create the launch.json because once it’s created, you have to maintain it (and I think F5-without-launch.json is best for most people).

@pulyaevskiy What do you think?