DependencyContextAssemblyProvider assumes the entry assembly has a .deps.json file

[DavidObando]

Tests in the aspnet/Performance repo are failing because DependencyContextAssemblyProvider.GetCandidateLibraries() assumes that DependencyContext.Default is not null. Our tests are throwing a System.NullReferenceException when accessing DependencyContext.Default as it's null.

Note that the current implementation of DependencyContext.get_Default() allows for it to be null when the entry assembly (in our case xunit.console.exe) doesn't provide a dependencies description file (in our case xunit.console.deps.json).

Let me know if I'm interpreting something wrong, this has the Performance repository blocked aspnet/Performance#62.

@NTaylorMullen @muratg @sajayantony

[davidfowl]

That's fixed in #4088

[muratg]

@pranavkm will check his change in soon, so this should be a non-issue soon.

[pranavkm]

Fixed in 5b805bb

[pranavkm]

We still null ref with this change. Should we throw an exception stating you should set the preserveCompilationContext flag if DependencyContext.Load returns null?

[pranavkm]

Self assigning since this would be a relatively small fix.

[davidfowl]

Then we need 2 APIs. TryLoad and Load

[davidfowl]

Why are we still null reffing?

[pranavkm]

There's an obvious bug in my code (I call DependencyContext.Default) - but what happens when DependencyContext.Load returns null? Do we only look at the assembly specified by IApplicationEnvironment.ApplicationName for controllers? Or should we throw an error saying you probably forgot to include the setting in project.json?

[davidfowl]

There's an obvious bug in my code (I call DependencyContext.Default) - but what happens when DependencyContext.Load returns null?

There's no deps file so act like it returns 0 results.

Do we only look at the assembly specified by IApplicationEnvironment.ApplicationName for controllers?

Yes. IApplicationEnvironment.ApplicationName is ASP.NET's abstraction over entry assembly.

Or should we throw an error saying you probably forgot to include the setting in project.json?

This is tricky. Right now I would say don't throw. Especially in light of this dotnet/cli@acd581c