Setting RunCommand/StartProgram on ClassLibrary doesn't work in new project system

[eerhardt]

In the old .csproj, you could set the following properties on an <OutputType>Library</OutputType> project:

• StartAction = Program
• StartProgram
• StartArguments
• StartWorkingDirectory

And when you F5'd in VS, it would launch the StartProgram as expected.

In the Microsoft.NET.Sdk, it translates these properties to the new RunCommand, RunArguments and RunWorkingDirectory properties that are used as the contract between the MSBuild project and both VS and dotnet run for how to execute/run the project.
See https://github.com/dotnet/sdk/blob/0af8aa984773c32752634a62c87edcceedcb93e3/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.targets#L387-L397

However, the project-system explicitly blocks F5'ing an project with <OutputType>Library</OutputType>.

project-system/src/Microsoft.VisualStudio.ProjectSystem.Managed.VS/ProjectSystem/VS/Debug/ConsoleDebugTargetsProvider.cs

Lines 228 to 235 in 47787b3

	// If we're launching for debug purposes, prevent someone F5'ing a class library
	if (validateSettings && await IsClassLibraryAsync().ConfigureAwait(false))
	{
	throw new Exception(VSResources.ProjectNotRunnableDirectly);
	}
	// Get the executable to run, the arguments and the default working directory
	Tuple<string, string, string> runData = await GetRunnableProjectInformationAsync(configuredProject).ConfigureAwait(false);

This kind of limiting shouldn't be done by the project-system. If the project returns a valid RunCommand, the project-system should run it, no matter what the <OutputType> is set to.

This is a breaking change from the old project system to the new. Setting StartAction and StartProgram should "just work" in the new project system.

/cc @BillHiebert

[Pilchie]

@davkean just changed some of this code I thought too.

[Pilchie]

Also, pretty sure that if you specify a program in your launchSettings.json this will work, though you'd have to duplicate what you had in the .csproj.

[eerhardt]

if you specify a program in your launchSettings.json this will work, though you'd have to duplicate what you had in the .csproj.

The scenario I ran into this is with dotnet/corefx test projects. We are setting StartAction and StartProgram to allow developers to F5 the test projects, which then invokes the xunit console runner. (Yes, we want to get this integrated into Test Explorer, but we can't change everything all at once. Moving to SDK-style projects and the new project system is the first step.)

dotnet/corefx has on the order of 100 test .csprojs, and the MSBuild options are set in .targets files. So duplicating this information in ~100 launchSettings.json files doesn't seem realistic.

[Pilchie]

Not ideal, but possible - dotnet/roslyn#21014 (edited for sp)