fix: Path.GetTempPath should end with directory separator (#1172)

`Path.GetTempPath` should end with directory separator

Author: vbreuss

src/TestableIO.System.IO.Abstractions.TestingHelpers/MockFileSystem.cs

@@ -14,7 +14,7 @@ namespace System.IO.Abstractions.TestingHelpers
     public class MockFileSystem : FileSystemBase, IMockFileDataAccessor
     {
         private const string DEFAULT_CURRENT_DIRECTORY = @"C:\";
-        private const string TEMP_DIRECTORY = @"C:\temp";
+        private const string TEMP_DIRECTORY = @"C:\temp\";
 
         private readonly IDictionary<string, FileSystemEntry> files;
         private readonly IDictionary<string, MockDriveData> drives;

tests/TestableIO.System.IO.Abstractions.TestingHelpers.Tests/MockPathTests.cs

@@ -382,6 +382,20 @@ public void GetTempPath_Called_ReturnsStringLengthGreaterThanZero()
             Assert.That(result.Length > 0, Is.True);
         }
 
+        [Test]
+        public void GetTempPath_ShouldEndWithDirectorySeparator()
+        {
+            //Arrange
+            var mockPath = new MockFileSystem().Path;
+            var directorySeparator = mockPath.DirectorySeparatorChar.ToString();
+
+            //Act
+            var result = mockPath.GetTempPath();
+
+            //Assert
+            Assert.That(result, Does.EndWith(directorySeparator));
+        }
+
         [Test]
         [TestCase(null)]
         [TestCase("")]