Adding a separate abstraction for the NuGet sentinel.

src/Microsoft.DotNet.Configurer/DotnetFirstTimeUseConfigurer.cs

@@ -9,25 +9,13 @@ namespace Microsoft.DotNet.Configurer
 {
     public class DotnetFirstTimeUseConfigurer
     {
-        public static readonly string SENTINEL = $"{Product.Version}.dotnetSentinel";
-
-        private IFile _file;
         private INuGetCachePrimer _nugetCachePrimer;
-        private INuGetCacheResolver _nugetCacheResolver;
+        private INuGetCacheSentinel _nugetCacheSentinel;
 
-        public DotnetFirstTimeUseConfigurer(INuGetCachePrimer nugetCachePrimer, INuGetCacheResolver nugetCacheResolver)
+        public DotnetFirstTimeUseConfigurer(INuGetCachePrimer nugetCachePrimer, INuGetCacheSentinel nugetCacheSentinel)
-            : this(nugetCachePrimer, nugetCacheResolver, FileSystemWrapper.Default.File)
         {
-        }
-
-        internal DotnetFirstTimeUseConfigurer(
-            INuGetCachePrimer nugetCachePrimer,
-            INuGetCacheResolver nugetCacheResolver,
-            IFile file)
-        {
-            _file = file;
             _nugetCachePrimer = nugetCachePrimer;
-            _nugetCacheResolver = nugetCacheResolver;
+            _nugetCacheSentinel = nugetCacheSentinel;
         }
 
         public void Configure()
@@ -40,10 +28,7 @@ namespace Microsoft.DotNet.Configurer
 
         private bool ShouldPrimeNugetCache()
         {
-            var nugetCachePath = _nugetCacheResolver.ResolveNugetCachePath();
+            return !_nugetCacheSentinel.Exists();
-            var sentinel = Path.Combine(nugetCachePath, SENTINEL);
-
-            return !_file.Exists(sentinel);
         }
     }
 }

src/Microsoft.DotNet.Configurer/INuGetCacheSentinel.cs

@@ -3,8 +3,8 @@
 
 namespace Microsoft.DotNet.Configurer
 {
-	public interface INuGetCacheResolver
+	public interface INuGetCacheSentinel
 	{
-		string ResolveNugetCachePath();
+		bool Exists();
 	}
 }

src/Microsoft.DotNet.Configurer/NuGetCacheResolver.cs

@@ -1,15 +0,0 @@
-// 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 Microsoft.DotNet.ProjectModel.Resolution;
-
-namespace Microsoft.DotNet.Configurer
-{
-    public class NuGetCacheResolver : INuGetCacheResolver
-    {
-        public string ResolveNugetCachePath()
-        {
-            return PackageDependencyProvider.ResolvePackagesPath(null, null);
-        }
-    }
-}

src/Microsoft.DotNet.Configurer/NuGetCacheSentinel.cs

@@ -0,0 +1,34 @@
+// 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 System.IO;
+using Microsoft.DotNet.Cli.Utils;
+using Microsoft.Extensions.EnvironmentAbstractions;
+using Microsoft.DotNet.ProjectModel.Resolution;
+
+namespace Microsoft.DotNet.Configurer
+{
+    public class NuGetCacheSentinel : INuGetCacheSentinel
+    {
+        public static readonly string SENTINEL = $"{Product.Version}.dotnetSentinel";
+
+        private readonly IFile _file;
+
+        public NuGetCacheSentinel() : this(FileSystemWrapper.Default.File)
+        {
+        }
+
+        internal NuGetCacheSentinel(IFile file)
+        {
+            _file = file;
+        }
+
+        public bool Exists()
+        {
+            var nugetCachePath = PackageDependencyProvider.ResolvePackagesPath(null, null);
+            var sentinel = Path.Combine(nugetCachePath, SENTINEL);
+
+            return !_file.Exists(sentinel);
+        }
+    }
+}

test/Microsoft.DotNet.Configurer.UnitTests/GivenADotnetFirstTimeUseConfigurer.cs

@@ -6,7 +6,6 @@ using Microsoft.DotNet.Cli.Utils;
 using Microsoft.DotNet.Configurer;
 using Microsoft.DotNet.Tools.Test;
 using Microsoft.Extensions.DependencyModel.Tests;
-using Microsoft.Extensions.EnvironmentAbstractions;
 using Moq;
 using Xunit;
 
@@ -14,36 +13,23 @@ namespace Microsoft.DotNet.Configurer.UnitTests
 {
     public class GivenADotnetFirstTimeUseConfigurer
     {
-        private const string NUGET_CACHE_PATH = "some path";
-
         private Mock<INuGetCachePrimer> _nugetCachePrimerMock;
-        private Mock<INuGetCacheResolver> _nugetCacheResolverMock;
+        private Mock<INuGetCacheSentinel> _nugetCacheSentinelMock;
 
         public GivenADotnetFirstTimeUseConfigurer()
         {
             _nugetCachePrimerMock = new Mock<INuGetCachePrimer>();
-            _nugetCacheResolverMock = new Mock<INuGetCacheResolver>();
+            _nugetCacheSentinelMock = new Mock<INuGetCacheSentinel>();
-            _nugetCacheResolverMock.Setup(n => n.ResolveNugetCachePath()).Returns(NUGET_CACHE_PATH);
-        }
-
-        [Fact]
-        public void The_sentinel_has_the_current_version_in_its_name()
-        {
-            DotnetFirstTimeUseConfigurer.SENTINEL.Should().Contain($"{Product.Version}");
         }
 
         [Fact]
         public void It_does_not_prime_the_cache_if_the_sentinel_exists()
         {
-            var fileSystemMockBuilder = FileSystemMockBuilder.Create();
+            _nugetCacheSentinelMock.Setup(n => n.Exists()).Returns(true);
-            fileSystemMockBuilder.AddFiles(NUGET_CACHE_PATH, DotnetFirstTimeUseConfigurer.SENTINEL);
-
-            var fileSystemMock = fileSystemMockBuilder.Build();
 
             var dotnetFirstTimeUseConfigurer = new DotnetFirstTimeUseConfigurer(
                 _nugetCachePrimerMock.Object,
-                _nugetCacheResolverMock.Object,
+                _nugetCacheSentinelMock.Object);
-                fileSystemMock.File);
 
             dotnetFirstTimeUseConfigurer.Configure();
 
@@ -53,13 +39,11 @@ namespace Microsoft.DotNet.Configurer.UnitTests
         [Fact]
         public void It_primes_the_cache_if_the_sentinel_does_not_exist()
         {
-            var fileSystemMockBuilder = FileSystemMockBuilder.Create();
+            _nugetCacheSentinelMock.Setup(n => n.Exists()).Returns(false);
-            var fileSystemMock = fileSystemMockBuilder.Build();
 
             var dotnetFirstTimeUseConfigurer = new DotnetFirstTimeUseConfigurer(
                 _nugetCachePrimerMock.Object,
-                _nugetCacheResolverMock.Object,
+                _nugetCacheSentinelMock.Object);
-                fileSystemMock.File);
 
             dotnetFirstTimeUseConfigurer.Configure();
 

test/Microsoft.DotNet.Configurer.UnitTests/GivenANuGetCacheSentinel.cs

@@ -0,0 +1,46 @@
+// 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.Cli.Utils;
+using Microsoft.DotNet.Configurer;
+using Microsoft.Extensions.DependencyModel.Tests;
+using Xunit;
+
+namespace Microsoft.DotNet.Configurer.UnitTests
+{
+    public class GivenANuGetCacheSentinel
+    {
+        private const string NUGET_CACHE_PATH = "some path";
+
+        [Fact]
+        public void The_sentinel_has_the_current_version_in_its_name()
+        {
+            NuGetCacheSentinel.SENTINEL.Should().Contain($"{Product.Version}");
+        }
+
+        [Fact]
+        public void It_returns_true_if_the_sentinel_exists()
+        {
+            var fileSystemMockBuilder = FileSystemMockBuilder.Create();
+            fileSystemMockBuilder.AddFiles(NUGET_CACHE_PATH, NuGetCacheSentinel.SENTINEL);
+
+            var fileSystemMock = fileSystemMockBuilder.Build();
+
+            var nugetCacheSentinel = new NuGetCacheSentinel(fileSystemMock.File);
+
+            nugetCacheSentinel.Exists().Should().BeTrue();
+        }
+
+        [Fact]
+        public void It_returns_false_if_the_sentinel_does_not_exist()
+        {
+            var fileSystemMockBuilder = FileSystemMockBuilder.Create();
+            var fileSystemMock = fileSystemMockBuilder.Build();
+
+            var nugetCacheSentinel = new NuGetCacheSentinel(fileSystemMock.File);
+
+            nugetCacheSentinel.Exists().Should().BeTrue();
+        }
+    }
+}