Fix template list parsing on non-English systems

[jmiven]

To list the available templates, FSAC parses directly the output of dotnet new --list, looking for predefined English words. But if the configured display language / locale of the system is another language (e.g. French or German), this parsing fails and generates an out-of-bounds exception.

This commit takes the simplest route to fix the problem: forcing dotnet to print its output in English by setting a documented environment variable[1].

Fixes ionide/ionide-vscode-fsharp#1569

[1] https://docs.microsoft.com/en-us/dotnet/core/tools/dotnet-environment-variables#dotnet_cli_ui_language

[baronfel]

Thanks! Could you try adding a test to ensure we don't regress here? The tests for templates are here, and I think a good test would:

• get the current locale (should be English, but worth checking here)
• set the locale to something non-English
• call the list function
• ensure it parses
• re-set the old locale

the tests can be run with dotnet run or dotnet test.

[jmiven]

I agree that adding a regression test is important. But I'm hitting a roadblock, as I don't know .NET well for the time being. I've tried setting Thread.CurrentThread.CurrentCulture and CultureInfo.DefaultThreadCurrentCulture before calling the list function but neither of them modify the locale/culture for the new process.

Do you know how to do this?

[baronfel]

Since new processes inherit their environment from their parents, I was thinking that you could use System.Environment's GetEnvironmentVariable and SetEnvironmentVariable methods to implement the steps above.

it might look something like

// save previous env
let priorEnv = System.Environment.GetEnvironmentVariable "DOTNET_CLI_UI_LANGUAGE"
// set env for this call
System.Environment.SetEnvironmentVariable("DOTNET_CLI_UI_LANGUAGE", "en-US")
// perform the test call
let templates = ....... // actual code goes here
// whatever the assertions are would go here
......
// put the old state back for the remainder of the tests
System.Environment.SetEnvironmentVariable("DOTNET_CLI_UI_LANGUAGE", priorEnv)

there might be some null-checking required there, but that's about what I was thinking.

[jmiven]

I wasn't thinking of the DOTNET_CLI_UI_LANGUAGE, good idea, thanks!

Testing definitely was a good idea as my initial fix was wrong! :-)

[baronfel]

This changeset looks great, I especially appreciate how you made the save and restore after use pattern work using a higher-order-function.

[baronfel]

Your new tests look like they're passing just fine. I'll go ahead and merge this and we'll start working on a release with it soon. Thanks again for being willing to make this fix!

[jmiven]

Thanks for guiding me!

[baronfel]

This has been released in FSAC 0.47.2