Fixing dotnet migrate global.json. This was failing because we were turning global.json into an empty string and trying to construct a directory for it. The fix was to detect this and transform it into a . directory. Migrate is already respecting the projects node in global.json.

TestAssets/TestProjects/AppWithPackageNamedAfterFolder/TestAssets/TestAsset/Program.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace App.Tests
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            Console.WriteLine("Hello World from Test asset!");
+        }
+    }
+}

TestAssets/TestProjects/AppWithPackageNamedAfterFolder/TestAssets/TestAsset/project.json

@@ -0,0 +1,15 @@
+{
+  "frameworks": {
+    "netcoreapp1.0": {
+      "imports": [
+        "portable-net451+win8"
+      ],
+      "dependencies": {
+        "Microsoft.NETCore.App": {
+          "version": "1.0.0",
+          "type": "platform"
+        }
+      }
+    }
+  }
+}

TestAssets/TestProjects/AppWithPackageNamedAfterFolder/global.json

@@ -1,6 +1,6 @@
 {
   "projects": [
-    "App",
+    "src",
-    "App.Tests"
+    "test"
   ]
 }

src/dotnet/commands/dotnet-migrate/MigrateCommand.cs

@@ -364,12 +364,7 @@ namespace Microsoft.DotNet.Tools.Migrate
 
         private IEnumerable<string> GetProjectsFromGlobalJson(string globalJson)
         {
-            if (!File.Exists(globalJson))
+            var searchPaths = ProjectDependencyFinder.GetGlobalPaths(GetGlobalJsonDirectory(globalJson));
-            {
-                throw new GracefulException($"Unable to find global settings file at {globalJson}");
-            }
-
-            var searchPaths = ProjectDependencyFinder.GetGlobalPaths(Path.GetDirectoryName(globalJson));
 
             foreach (var searchPath in searchPaths)
             {
@@ -392,6 +387,17 @@ namespace Microsoft.DotNet.Tools.Migrate
             }
         }
 
+        private string GetGlobalJsonDirectory(string globalJson)
+        {
+            if (!File.Exists(globalJson))
+            {
+                throw new GracefulException($"Unable to find global settings file at {globalJson}");
+            }
+
+            var globalJsonDirectory = Path.GetDirectoryName(globalJson);
+            return string.IsNullOrEmpty(globalJsonDirectory) ? "." : globalJsonDirectory;
+        }
+
         private IEnumerable<string> GetProjectsFromSolution(string slnPath)
         {
             if (!File.Exists(slnPath))

test/dotnet-migrate.Tests/GivenThatIWantToMigrateAppsUsingGlobalJson.cs

@@ -0,0 +1,42 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using FluentAssertions;
+using Microsoft.DotNet.TestFramework;
+using Microsoft.DotNet.Tools.Test.Utilities;
+using System.IO;
+using Xunit;
+
+namespace Microsoft.DotNet.Migration.Tests
+{
+    public class GivenThatIWantToMigrateAppsUsingGlobalJson : TestBase
+    {
+        [Fact]
+        public void ItMigratesWhenBeingPassedAFullPathToGlobalJson()
+        {
+            var solutionDirectory =
+                TestAssetsManager.CreateTestInstance("AppWithPackageNamedAfterFolder").Path;
+            var globalJsonPath = Path.Combine(solutionDirectory, "global.json");
+
+            new TestCommand("dotnet")
+                    .WithForwardingToConsole()
+                    .Execute($"migrate {globalJsonPath}")
+                    .Should()
+                    .Pass();
+        }
+
+        [Fact]
+        public void ItMigratesWhenBeingPassedJustGlobalJson()
+        {
+            var solutionDirectory =
+                TestAssetsManager.CreateTestInstance("AppWithPackageNamedAfterFolder").Path;
+
+            new TestCommand("dotnet")
+                    .WithWorkingDirectory(solutionDirectory)
+                    .WithForwardingToConsole()
+                    .Execute($"migrate global.json")
+                    .Should()
+                    .Pass();
+        }
+    }
+}