Ensure FileInfo is not relative in DirectoryInfoProxy (microsoft#1519)

* Ensure FileInfo is not relative in DirectoryInfoProxy

* Add tests

Author: jakebailey

src/Core/Impl/IO/DirectoryInfoProxy.cs

@@ -55,7 +55,7 @@ public IEnumerable<IFileSystemInfo> EnumerateFileSystemInfos(string[] includePat
             var matcher = GetMatcher(includePatterns, excludePatterns);
             PatternMatchingResult matchResult = SafeExecuteMatcher(matcher);
             return matchResult.Files.Select((filePatternMatch) => {
-                var path = PathUtils.NormalizePath(filePatternMatch.Path);
+                var path = PathUtils.NormalizePath(Path.Combine(_directoryInfo.FullName, filePatternMatch.Path));
                 return CreateFileSystemInfoProxy(new FileInfo(path));
             });
         }

src/Core/Test/AssemblySetup.cs

@@ -0,0 +1,34 @@
+// Copyright(c) Microsoft Corporation
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the License); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+//
+// THIS CODE IS PROVIDED ON AN  *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS
+// OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY
+// IMPLIED WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABILITY OR NON-INFRINGEMENT.
+//
+// See the Apache Version 2.0 License for specific language governing
+// permissions and limitations under the License.
+
+using Microsoft.Python.Core.Testing;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using TestUtilities;
+
+namespace Microsoft.Python.Core.Tests {
+    [TestClass]
+    public sealed class AssemblySetup {
+        [AssemblyInitialize]
+        public static void Initialize(TestContext testContext) => AnalysisTestEnvironment.Initialize();
+
+        private class AnalysisTestEnvironment : TestEnvironmentImpl, ITestEnvironment {
+            public static void Initialize() {
+                var instance = new AnalysisTestEnvironment();
+                Instance = instance;
+                TestEnvironment.Current = instance;
+            }
+        }
+    }
+}

src/Core/Test/DirectoryInfoProxyTests.cs

@@ -0,0 +1,51 @@
+// Copyright(c) Microsoft Corporation
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the License); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+//
+// THIS CODE IS PROVIDED ON AN  *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS
+// OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY
+// IMPLIED WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABILITY OR NON-INFRINGEMENT.
+//
+// See the Apache Version 2.0 License for specific language governing
+// permissions and limitations under the License.
+
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.Python.Core.IO;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using TestUtilities;
+
+namespace Microsoft.Python.Core.Tests {
+    [TestClass]
+    public class DirectoryInfoProxyTests {
+        public TestContext TestContext { get; set; }
+
+        [TestInitialize]
+        public void TestInitialize()
+            => TestEnvironmentImpl.TestInitialize($"{TestContext.FullyQualifiedTestClassName}.{TestContext.TestName}");
+
+        [TestCleanup]
+        public void Cleanup() => TestEnvironmentImpl.TestCleanup();
+
+        [TestMethod, Priority(0)]
+        public async Task EnumerateFileSystemInfos() {
+            var root = TestData.GetTestSpecificPath();
+            await TestData.CreateTestSpecificFileAsync("a_y.py", "not important");
+            await TestData.CreateTestSpecificFileAsync("b_y.py", "not important");
+            await TestData.CreateTestSpecificFileAsync("c_z.py", "not important");
+
+            var proxy = new DirectoryInfoProxy(root);
+            var files = proxy.EnumerateFileSystemInfos(new[] { "*.py" }, new[] { "*z.py" }).OrderBy(x => x.FullName).ToArray();
+            files.Should().HaveCount(2);
+
+            files[0].FullName.Should().Be(Path.Combine(root, "a_y.py"));
+            files[1].FullName.Should().Be(Path.Combine(root, "b_y.py"));
+        }
+    }
+}