Make CancellationToken a required parameter

Author: AArnott

src/CodeGeneration.Roslyn.Engine/DocumentTransform.cs

@@ -50,7 +50,7 @@ public static async Task<SyntaxTree> TransformAsync(
             string projectDirectory,
             Func<AssemblyName, Assembly> assemblyLoader,
             IProgress<Diagnostic> progress,
-            CancellationToken cancellationToken = default)
+            CancellationToken cancellationToken)
         {
             Requires.NotNull(compilation, nameof(compilation));
             Requires.NotNull(inputDocument, nameof(inputDocument));

src/CodeGeneration.Roslyn.Tests/Helpers/CompilationTestsBase.cs

@@ -6,6 +6,7 @@
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Threading;
 using System.Threading.Tasks;
 using CodeGeneration.Roslyn;
 using CodeGeneration.Roslyn.Engine;
@@ -78,7 +79,7 @@ protected static async Task<SyntaxTree> GenerateAsync(string source)
         var diagnostics = compilation.GetDiagnostics();
         Assert.Empty(diagnostics.Where(x => x.Severity >= DiagnosticSeverity.Warning));
         var progress = new Progress<Diagnostic>();
-        var result = await DocumentTransform.TransformAsync(compilation, tree, null, Assembly.Load, progress);
+        var result = await DocumentTransform.TransformAsync(compilation, tree, null, Assembly.Load, progress, CancellationToken.None);
         return result;
     }