Make AnalyzerResults deterministically ordered

The order itself is not relevant (the `NuGetFrameworkSorter` used to sort target frameworks doesn't guarantee any specific order anyway) but the order is deterministic, meaning that several builds of the same project will always yield the same order of the target frameworks and results.

The nondeterministic nature of the current implementation made it hard to diagnose an implementation issue in Stryker.NET: stryker-mutator/stryker-net#1899 (comment)

src/Buildalyzer/AnalyzerResults.cs

@@ -1,6 +1,7 @@
 using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Buildalyzer
 {
@@ -23,17 +24,17 @@ internal void Add(IEnumerable<IAnalyzerResult> results, bool overallSuccess)
 
         public IAnalyzerResult this[string targetFramework] => _results[targetFramework];
 
-        public IEnumerable<string> TargetFrameworks => _results.Keys;
+        public IEnumerable<string> TargetFrameworks => _results.Keys.OrderBy(e => e, TargetFrameworkComparer.Instance);
 
-        public IEnumerable<IAnalyzerResult> Results => _results.Values;
+        public IEnumerable<IAnalyzerResult> Results => TargetFrameworks.Select(e => _results[e]);
 
         public int Count => _results.Count;
 
         public bool ContainsTargetFramework(string targetFramework) => _results.ContainsKey(targetFramework);
 
         public bool TryGetTargetFramework(string targetFramework, out IAnalyzerResult result) => _results.TryGetValue(targetFramework, out result);
 
-        public IEnumerator<IAnalyzerResult> GetEnumerator() => _results.Values.GetEnumerator();
+        public IEnumerator<IAnalyzerResult> GetEnumerator() => Results.GetEnumerator();
 
         IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
     }

src/Buildalyzer/Buildalyzer.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>netcoreapp3.1</TargetFrameworks>
     <Description>A little utility to perform design-time builds of .NET projects without having to think too hard about it. Should work with any project type on any .NET runtime.</Description>
@@ -8,6 +8,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging" Version="2.1.1" />
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="2.1.1" />
     <PackageReference Include="MsBuildPipeLogger.Server" Version="1.1.3" />
+    <PackageReference Include="NuGet.Frameworks" Version="6.0.0" />
     <PackageReference Include="System.Reflection.TypeExtensions" Version="4.7.0" />
     <PackageReference Include="Microsoft.Build" Version="16.9.0" />
     <PackageReference Include="Microsoft.Build.Framework" Version="16.9.0" />

src/Buildalyzer/TargetFrameworkComparer.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+using NuGet.Frameworks;
+
+namespace Buildalyzer
+{
+    internal class TargetFrameworkComparer : IComparer<string>
+    {
+        public static readonly TargetFrameworkComparer Instance = new TargetFrameworkComparer();
+
+        private static readonly NuGetFrameworkSorter Sorter = new NuGetFrameworkSorter();
+
+        private TargetFrameworkComparer()
+        {
+        }
+
+        public int Compare(string x, string y)
+        {
+            NuGetFramework xFramework = NuGetFramework.ParseFolder(x);
+            NuGetFramework yFramework = NuGetFramework.ParseFolder(y);
+            return Sorter.Compare(xFramework, yFramework);
+        }
+    }
+}

tests/Buildalyzer.Tests/Integration/SimpleProjectsFixture.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
@@ -236,7 +236,7 @@ public void MultiTargetingBuildAllTargetFrameworksGetsSourceFiles()
             // Then
             // Multi-targeting projects product an extra result with an empty target framework that holds some MSBuild properties (I.e. the "outer" build)
             results.Count.ShouldBe(3);
-            results.TargetFrameworks.ShouldBe(new[] { "net462", "netstandard2.0", string.Empty }, true, log.ToString());
+            results.TargetFrameworks.ShouldBe(new[] { "net462", "netstandard2.0", string.Empty }, ignoreOrder: false, log.ToString());
             results[string.Empty].SourceFiles.ShouldBeEmpty();
             new[]
             {