Make src/Analyzers tests pass successfully locally in Vs2019

[tebeco]

Summary of the changes (Less than 80 chars)

• Applying suggesting fix from https://github.com/dotnet/aspnetcore/isses/10422
• use "CopyToOutputDirectory" rather than "CopyToPublishDirectory"

Addresses #bugnumber (not created yet)

As i have no idea if it will break the CI or not, i did not created an issue yet

[sharwell]

It looks like this project is using an analyzer test framework called "Microsoft.AspNetCore.Analyzer.Testing", which so far I haven't been able to find. This is not the standard analyzer test framework, so the first step on testing is to remove this reference and instead use Microsoft.CodeAnalysis.Testing. I'm still investigating the steps necessary to do this for this repository.

[tebeco]

AHAH, yeah It took me time to find it too
I think It was from extensions and probably now in dotnet/extensions

(As you know this repo is going to be moved to both dotnet/runtime and dotnet/aspnetcore

EDIT :
https://github.com/dotnet/extensions/tree/master/src/TestingUtils

[sharwell]

I cannot figure out what this is testing:

aspnetcore/src/Analyzers/Analyzers/test/CompilationFeatureDetectorTest.cs

Lines 14 to 29 in c7d4d7c

	[Fact]
	public async Task DetectFeaturesAsync_FindsNoFeatures()
	{
	// Arrange
	var compilation = await CreateCompilationAsync(nameof(StartupWithNoFeatures));
	var symbols = new StartupSymbols(compilation);
	var type = (INamedTypeSymbol)compilation.GetSymbolsWithName(nameof(StartupWithNoFeatures)).Single();
	Assert.True(StartupFacts.IsStartupClass(symbols, type));
	// Act
	var features = await CompilationFeatureDetector.DetectFeaturesAsync(compilation);
	// Assert
	Assert.Empty(features);
	}

[tebeco]

This test seems to be analyzing StartupWithNoFeatures.cs
File is here

aspnetcore/src/Analyzers/Analyzers/test/TestFiles/CompilationFeatureDetectorTest/StartupWithNoFeatures.cs

Lines 8 to 18 in c7d4d7c

	public class StartupWithNoFeatures
	{
	public void Configure(IApplicationBuilder app)
	{
	app.UseRouting();
	app.UseEndpoints(endpoints =>
	{
	endpoints.MapFallbackToFile("index.html");
	});
	}

The CompilationFeatureDetector seems to recreate AdhockWorkspace and add the specified StartupFoo.cs to it

     var compilation = await CreateCompilationAsync(nameof(StartupWithNoFeatures));   <=== recreate the workspace

This code ensure that it properly detect it as a Startup file/class

     var type = (INamedTypeSymbol)compilation.GetSymbolsWithName(nameof(StartupWithNoFeatures)).Single(); 
     Assert.True(StartupFacts.IsStartupClass(symbols, type)); 

And then each StartupFoo.cs has it own specificity (Feature ?)
this part is supposed to find features :
CompilationFeatureDetector.DetectFeaturesAsync(compilation)

and it's not supposed to find any :
Assert.Empty(features);

[tebeco]

also the following line is VERY VERY confusion in the Arange part, because in fact it's only used to detect if it's an actual Startup class
var symbols = new StartupSymbols(compilation);

If you dig in CompilationFeatureDetector.DetectFeaturesAsync you will see that this method does the exact same thing ... but internally (no noise outside the API, there may be reason, no idea) :

aspnetcore/src/Analyzers/Analyzers/src/CompilationFeatureDetector.cs

Lines 16 to 25 in c7d4d7c

	public static async Task<IImmutableSet<string>> DetectFeaturesAsync(
	Compilation compilation,
	CancellationToken cancellationToken = default)
	{
	var symbols = new StartupSymbols(compilation);
	if (!symbols.HasRequiredSymbols)
	{
	// Cannot find ASP.NET Core types.
	return ImmutableHashSet<string>.Empty;
	}

Also i'm not very sure about the Symbol thing, if i had to do a wild guess, i think it's to check that Symbols are "loaded/available" so that Roslyn can properly do it job when it's going to analyze the code later on.
I see it as a "Sanity check" (kinda like testing if(foo != null) before doing foo?.whatever

[sharwell]

I submitted #20277 to update the analyzer tests to the new library. I verified that this pull request fixes the experience for the remaining tests.

[tebeco]

I guessed that it was on purpose to make sure the code is actually seen as code and not as string
==> "it does build properly so the code is valid"

And later on the call to var compilation = await CreateCompilationAsync(nameof(StartupWithNoFeatures)); would automatically be able to resolve all dependencies since it does already build.

I guess this is now the job of CSharpVerifierHelper you added ?

[tebeco]

(i changed the status of the PR to Ready for review)

Honestly i was not sure about the changes since it implied both AppContext and few issue about Helix (i have no idea yet the detail, but i often see files/dependencies issue around it so i hope i did not make any regression here)

[tebeco]

@sharwell
Not sure if i should add or change anything else in that PR, i'm a bit lost now ;)

[sharwell]

This pull request seems fine to me.

[tebeco]

thx ;)