Merge pull request #5461 from cston/ng

Allow #r package reference without explicit version

src/Interactive/HostTest/NuGetPackageResolverTests.cs

@@ -155,8 +155,11 @@ public void ParsePackageNameAndVersion()
             ParseInvalidPackageReference("nuget:");
             ParseInvalidPackageReference("NUGET:");
             ParseInvalidPackageReference("nugetA/1");
-            ParseInvalidPackageReference("nuget:A");
-            ParseInvalidPackageReference("nuget:A.B");
+
+            ParseValidPackageReference("nuget:A", "A", "");
+            ParseValidPackageReference("nuget:A.B", "A.B", "");
+            ParseValidPackageReference("nuget:  ", "  ", "");
+
             ParseInvalidPackageReference("nuget:A/");
             ParseInvalidPackageReference("nuget:A//1.0");
             ParseInvalidPackageReference("nuget:/1.0.0");
@@ -199,6 +202,15 @@ public void WriteProjectJson()
   ""frameworks"": {
     ""net46"": {}
   }
+}");
+            WriteProjectJsonPackageReference("A", "",
+@"{
+  ""dependencies"": {
+    ""A"": """"
+  },
+  ""frameworks"": {
+    ""net46"": {}
+  }
 }");
             WriteProjectJsonPackageReference("\n\t", "\"'",
 @"{

src/Scripting/Core/Resolvers/NuGetPackageResolver.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Immutable;
+using System.Diagnostics;
 
 namespace Microsoft.CodeAnalysis.Scripting.Hosting
 {
@@ -10,20 +11,30 @@ internal abstract class NuGetPackageResolver
         private const string ReferencePrefix = "nuget:";
 
         /// <summary>
-        /// Syntax is "nuget:id/version".
+        /// Syntax is "nuget:name[/version]".
         /// </summary>
         internal static bool TryParsePackageReference(string reference, out string name, out string version)
         {
             if (reference.StartsWith(ReferencePrefix, StringComparison.Ordinal))
             {
                 var parts = reference.Substring(ReferencePrefix.Length).Split('/');
-                if ((parts.Length == 2) &&
-                    (parts[0].Length > 0) &&
-                    (parts[1].Length > 0))
+                Debug.Assert(parts.Length > 0);
+                name = parts[0];
+                if (name.Length > 0)
                 {
-                    name = parts[0];
-                    version = parts[1];
-                    return true;
+                    switch (parts.Length)
+                    {
+                        case 1:
+                            version = string.Empty;
+                            return true;
+                        case 2:
+                            version = parts[1];
+                            if (version.Length > 0)
+                            {
+                                return true;
+                            }
+                            break;
+                    }
                 }
             }
             name = null;