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[generator-Tests] Use Roslyn for .NET Core Support (#638)
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How do we test the C# output of `generator`?

*A* way is to check the output against "known good" files, which we do.

*Another* way is to use a compiler to ensure that the output compiles,
which we *also* do.

Unfortunately, the "just compile it!" approach has a major flaw, as
the easiest accessible C# compiler is
`Microsoft.CSharp.CSharpCodeProvider`, for use with System.CodeDom,
but *on Windows* `CSharpCodeProvider` only supports up to C# 5.

`generator`, meanwhile, may currently produce C# 8 output.

This conundrum was addressed in commit 968b474 by using the
[Microsoft.CodeDom.Providers.DotNetCompilerPlatform][0] NuGet package
when running on Windows, as that supported C#6+.

Unfortunately, `DotNetCompilerPlatform` does *not* run under .NET Core,
because it uses the MSBuild `CodeTaskFactory` which is not available on
.NET Core.  ([This issue has been fixed][1]; the fix is unreleased.)

Now that we support multitargeting net471 and netcoreapp3.1 (95f698b),
we would like to be able to build *and run* our unit tests under
.NET Core as well as Mono (macOS) or .NET Framework (Windows).

Migrate away from the `DotNetCompilerPlatform` NuGet package and
instead use the [Microsoft.CodeAnalysis.CSharp][2] NuGet package,
which contains an up-to-date C#8 Roslyn compiler.  This new package
supports .NET Core; we just need to update `Compiler.Compile()` to
work in terms of Roslyn SyntaxTrees instead of CodeDom objects.

This allows us to run the `generator` unit tests under .NET Core:

	dotnet test bin\TestDebug\generator-tests.dll

[0]: https://www.nuget.org/packages/Microsoft.CodeDom.Providers.DotNetCompilerPlatform/
[1]: aspnet/RoslynCodeDomProvider#51
[2]: https://www.nuget.org/packages/Microsoft.CodeAnalysis.CSharp/
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@jpobst
jpobst committed Apr 30, 2020
1 parent 56955d9 commit cbb50af
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Showing 2 changed files with 63 additions and 54 deletions.
115 changes: 62 additions & 53 deletions tests/generator-Tests/Integration-Tests/Compiler.cs
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Original file line number Diff line number Diff line change
@@ -1,44 +1,29 @@
using System;
using System.Reflection;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using NUnit.Framework;

namespace generatortests
{
public static class Compiler
{
const string RoslynEnvironmentVariable = "ROSLYN_COMPILER_LOCATION";
private static string unitTestFrameworkAssemblyPath = typeof(Assert).Assembly.Location;
private static string supportFilePath = typeof(Compiler).Assembly.Location;

static CodeDomProvider GetCodeDomProvider ()
{
if (Environment.OSVersion.Platform == PlatformID.Win32NT) {
//NOTE: there is an issue where Roslyn's csc.exe isn't copied to output for non-ASP.NET projects
// Comments on this here: https://stackoverflow.com/a/40311406/132442
// They added an environment variable as a workaround: https://github.com/aspnet/RoslynCodeDomProvider/pull/12
if (string.IsNullOrEmpty (Environment.GetEnvironmentVariable (RoslynEnvironmentVariable, EnvironmentVariableTarget.Process))) {
string roslynPath = Path.GetFullPath (Path.Combine (unitTestFrameworkAssemblyPath, "..", "..", "..", "packages", "microsoft.codedom.providers.dotnetcompilerplatform", "2.0.1", "tools", "RoslynLatest"));
Environment.SetEnvironmentVariable (RoslynEnvironmentVariable, roslynPath, EnvironmentVariableTarget.Process);
}

return new Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider ();
} else {
return new Microsoft.CSharp.CSharpCodeProvider ();
}
}
private static string supportFilePath = typeof (Compiler).Assembly.Location;
private static string unitTestFrameworkAssemblyPath = typeof (Assert).Assembly.Location;

public static Assembly Compile (Xamarin.Android.Binder.CodeGeneratorOptions options,
string assemblyFileName, IEnumerable<string> AdditionalSourceDirectories,
out bool hasErrors, out string output, bool allowWarnings)
{
// Gather all the files we need to compile
var generatedCodePath = options.ManagedCallableWrapperSourceOutputDirectory;
var sourceFiles = Directory.EnumerateFiles (generatedCodePath, "*.cs",
SearchOption.AllDirectories).ToList ();
sourceFiles = sourceFiles.Select (x => Path.GetFullPath(x)).ToList ();
sourceFiles = sourceFiles.Select (x => Path.GetFullPath (x)).ToList ();

var supportFiles = Directory.EnumerateFiles (Path.Combine (Path.GetDirectoryName (supportFilePath), "SupportFiles"),
"*.cs", SearchOption.AllDirectories);
Expand All @@ -49,36 +34,51 @@ public static Assembly Compile (Xamarin.Android.Binder.CodeGeneratorOptions opti
sourceFiles.AddRange (additonal);
}

CompilerParameters parameters = new CompilerParameters ();
parameters.GenerateExecutable = false;
parameters.GenerateInMemory = true;
parameters.CompilerOptions = "/unsafe";
parameters.OutputAssembly = assemblyFileName;
parameters.ReferencedAssemblies.Add (unitTestFrameworkAssemblyPath);
parameters.ReferencedAssemblies.Add (typeof (Enumerable).Assembly.Location);

var binDir = Path.GetDirectoryName (typeof (BaseGeneratorTest).Assembly.Location);
var facDir = GetFacadesPath ();
parameters.ReferencedAssemblies.Add (Path.Combine (binDir, "Java.Interop.dll"));
parameters.ReferencedAssemblies.Add (Path.Combine (facDir, "netstandard.dll"));
#if DEBUG
parameters.IncludeDebugInformation = true;
#else
parameters.IncludeDebugInformation = false;
#endif

using (var codeProvider = GetCodeDomProvider ()) {
CompilerResults results = codeProvider.CompileAssemblyFromFile (parameters, sourceFiles.ToArray ());

hasErrors = false;

foreach (CompilerError message in results.Errors) {
hasErrors |= !message.IsWarning || !allowWarnings;
// Parse the source files
var syntax_trees = sourceFiles.Distinct ().Select (s => CSharpSyntaxTree.ParseText (File.ReadAllText (s))).ToArray ();

// Set up the assemblies we need to reference
var binDir = Path.GetDirectoryName (typeof (BaseGeneratorTest).Assembly.Location);
var facDir = GetFacadesPath ();

var references = new [] {
MetadataReference.CreateFromFile (unitTestFrameworkAssemblyPath),
MetadataReference.CreateFromFile (typeof(object).Assembly.Location),
MetadataReference.CreateFromFile (typeof(Enumerable).Assembly.Location),
MetadataReference.CreateFromFile (Path.Combine (binDir, "Java.Interop.dll")),
MetadataReference.CreateFromFile (Path.Combine (facDir, "netstandard.dll"))
};

// Compile!
var compilation = CSharpCompilation.Create (
Path.GetFileName (assemblyFileName),
syntaxTrees: syntax_trees,
references: references,
options: new CSharpCompilationOptions (OutputKind.DynamicallyLinkedLibrary, allowUnsafe: true));

// Save assembly to a memory stream and load it with reflection
using (var ms = new MemoryStream ()) {
var result = compilation.Emit (ms);
var success = result.Success && (allowWarnings || !result.Diagnostics.Any (d => d.Severity == DiagnosticSeverity.Warning));

if (!success) {
var failures = result.Diagnostics.Where (diagnostic =>
diagnostic.Severity == DiagnosticSeverity.Warning ||
diagnostic.Severity == DiagnosticSeverity.Error);

hasErrors = true;
output = OutputDiagnostics (failures);
} else {
ms.Seek (0, SeekOrigin.Begin);

hasErrors = false;
output = null;

return Assembly.Load (ms.ToArray ());
}
output = string.Join (Environment.NewLine, results.Output.Cast<string> ());

return results.CompiledAssembly;
}

return null;
}

static string GetFacadesPath ()
Expand All @@ -94,6 +94,15 @@ static string GetFacadesPath ()

return dir;
}

static string OutputDiagnostics (IEnumerable<Diagnostic> diagnostics)
{
var sb = new StringBuilder ();

foreach (var d in diagnostics)
sb.AppendLine ($"{d.Id}: {d.GetMessage ()} ({d.Location})");

return sb.ToString ();
}
}
}

2 changes: 1 addition & 1 deletion tests/generator-Tests/generator-Tests.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -13,11 +13,11 @@
<Import Project="..\..\build-tools\scripts\cecil.projitems" />

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.5.0" />
<PackageReference Include="nunit" Version="3.11.0" />
<PackageReference Include="NUnit.ConsoleRunner" Version="3.9.0" />
<PackageReference Include="NUnit3TestAdapter" Version="3.13.0" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
<PackageReference Include="Microsoft.CodeDom.Providers.DotNetCompilerPlatform" Version="2.0.1" />
</ItemGroup>

<ItemGroup>
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