address PR comments

lang/cs/Org.Apache.REEF.IO.Tests/TestAzureBlockBlobFileSystemE2E.cs

@@ -69,26 +69,22 @@ public void Dispose()
 
         private bool CheckBlobExists(ICloudBlob blob)
         {
-            var task = blob.ExistsAsync();
-            return task.Result;
+            return blob.ExistsAsync().GetAwaiter().GetResult();
         }
 
         private bool CheckContainerExists(CloudBlobContainer container)
         {
-            var task = container.ExistsAsync();
-            return task.Result;
+            return container.ExistsAsync().GetAwaiter().GetResult();
         }
 
         private ICloudBlob GetBlobReferenceFromServer(CloudBlobContainer container, string blobName)
         {
-            var task = container.GetBlobReferenceFromServerAsync(blobName);
-            return task.Result;
+            return container.GetBlobReferenceFromServerAsync(blobName).GetAwaiter().GetResult();
         }
 
         private string DownloadText(CloudBlockBlob blob)
         {
-            var task = blob.DownloadTextAsync();
-            return task.Result;
+            return blob.DownloadTextAsync().GetAwaiter().GetResult();
         }
 
         [Fact(Skip = SkipMessage)]
@@ -268,18 +264,34 @@ public void TestCopyFromLocalE2E()
         }
 
         [Fact(Skip = SkipMessage)]
-        public void TestIsDirectory()
+        public void TestIsDirectoryValidDirectoryLevel1E2E()
         {
-            const string Directory1 = "dir1";
-            const string Directory2 = "dir1/dir2";
-            const string Directory3 = "dir3";
-            var blockBlobs1 = CreateTempBlobs(Directory1);
-            CreateTempBlobs(Directory2);
+            const string Directory = "dir";
+            CreateTempBlobs(Directory);
+            Assert.True(_fileSystem.IsDirectory(PathToFile(Directory)));
+        }
 
-            Assert.True(_fileSystem.IsDirectory(PathToFile(Directory1)));
-            Assert.True(_fileSystem.IsDirectory(PathToFile(Directory2)));
-            Assert.False(_fileSystem.IsDirectory(PathToFile(Directory3)));
-            Assert.False(_fileSystem.IsDirectory(blockBlobs1.First().Uri));
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryValidDirectoryLevel2E2E()
+        {
+            const string Directory = "dir1/dir2";
+            CreateTempBlobs(Directory);
+            Assert.True(_fileSystem.IsDirectory(PathToFile(Directory)));
+        }
+
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryFakeDirectoryE2E()
+        {
+            const string Directory = "dir";
+            Assert.False(_fileSystem.IsDirectory(PathToFile(Directory)));
+        }
+
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryFileE2E()
+        {
+            const string Directory = "dir";
+            var blockBlobs = CreateTempBlobs(Directory);
+            Assert.False(_fileSystem.IsDirectory(blockBlobs.First().Uri));
         }
 
         [Fact(Skip = SkipMessage)]
@@ -328,18 +340,16 @@ public void TestDeleteDirectorySecondLevelE2E()
             Assert.True(CheckContainerExists(_container));
         }
 
-        private List<CloudBlockBlob> CreateTempBlobs(string directory, int fileCount = 3)
+        private IEnumerable<CloudBlockBlob> CreateTempBlobs(string directory, int fileCount = 3)
         {
-            var blockBlobs = new List<CloudBlockBlob>();
-            for (var i = 0; i < fileCount; i++)
+            return Enumerable.Range(0, fileCount).Select(i =>
             {
                 var filePath = directory + '/' + i;
                 var blockBlob = _container.GetBlockBlobReference(filePath);
                 UploadFromString(blockBlob, "hello");
-                Assert.True(CheckBlobExists(blockBlob));
-                blockBlobs.Add(blockBlob);
-            }
-            return blockBlobs;
+                Assert.True(CheckBlobExists(blockBlob), "Blob does not exist: " + filePath);
+                return blockBlob;
+            });
         }
 
         private static void UploadFromString(ICloudBlob blob, string str)

lang/cs/Org.Apache.REEF.IO.Tests/TestAzureDataLakeFileSystemE2E.cs

@@ -195,16 +195,24 @@ public void TestCreateDirectoryE2E()
         }
 
         [Fact(Skip = SkipMessage)]
-        public void TestIsDirectoryE2E()
+        public void TestIsDirectoryValidDirectoryE2E()
         {
             string dirName = $"/{_defaultFolderName}";
-            string fakeDirName = $"/fakeDir";
-
             _adlsClient.CreateDirectory(dirName);
-            string fileName = UploadFromString(ContentsText);
+            Assert.True(_fileSystem.IsDirectory(PathToFile(dirName))); 
+        }
 
-            Assert.True(_fileSystem.IsDirectory(PathToFile(dirName)));
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryFakeDirectoryE2E()
+        {
+            string fakeDirName = $"/fakeDir";
             Assert.False(_fileSystem.IsDirectory(PathToFile(fakeDirName)));
+        }
+
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryFileE2E()
+        {
+            string fileName = UploadFromString(ContentsText);
             Assert.False(_fileSystem.IsDirectory(PathToFile(fileName)));
         }
 

lang/cs/Org.Apache.REEF.IO.Tests/TestHadoopFileSystem.cs

@@ -165,29 +165,47 @@ public void CreateUriForPathWithPrefix()
         }
 
         /// <summary>
-        /// Tests whether .IsDirectory() works.
+        /// Tests whether .IsDirectory() works for valid directory.
         /// </summary>
         [Fact(Skip = SkipMessage)]
-        public void TestIsDirectory()
+        public void TestIsDirectoryValidDirectory()
         {
             // Create directory
             var remoteDirUri = GetTempUri();
             _fileSystem.CreateDirectory(remoteDirUri);
 
+            Assert.True(_fileSystem.IsDirectory(remoteDirUri));
+
+            // Clean up
+            _fileSystem.DeleteDirectory(remoteDirUri);
+        }
+
+        /// <summary>
+        /// Tests whether .IsDirectory() works for fake directory.
+        /// </summary>
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryFakeDirectory()
+        {
             // Create fake directory uri
             var remoteFakeuri = GetTempUri();
 
+            Assert.False(_fileSystem.IsDirectory(remoteFakeuri));
+        }
+
+        /// <summary>
+        /// Tests whether .IsDirectory() works for file.
+        /// </summary>
+        [Fact(Skip = SkipMessage)]
+        public void TestIsDirectoryFile()
+        {
             // Create file
             var remoteFileUri = GetTempUri();
             var localFile = FileSystemTestUtilities.MakeLocalTempFile();
             _fileSystem.CopyFromLocal(localFile, remoteFileUri);
 
-            Assert.True(_fileSystem.IsDirectory(remoteDirUri));
-            Assert.False(_fileSystem.IsDirectory(remoteFakeuri));
             Assert.False(_fileSystem.IsDirectory(remoteFileUri));
 
             // Clean up
-            _fileSystem.DeleteDirectory(remoteDirUri);
             _fileSystem.Delete(remoteFileUri);
             File.Delete(localFile);
         }

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureBlob/AzureBlockBlobFileSystem.cs

@@ -133,9 +133,15 @@ public void CreateDirectory(Uri directoryUri)
         public bool IsDirectory(Uri uri)
         {
             var path = uri.AbsolutePath.TrimStart('/');
-            const int maxBlobResults = 1;
-            var blobItems = _client.ListBlobsSegmented(path, false, BlobListingDetails.Metadata, maxBlobResults, null, null, null).Results;
-            return blobItems.Any() && blobItems.First() is CloudBlobDirectory;
+            var blobItems = _client.ListBlobsSegmented(
+                path,
+                useFlatListing: false,
+                BlobListingDetails.Metadata,
+                maxResults: 1,
+                continuationToken: null,
+                blobRequestOptions: null,
+                operationContext: null).Results;
+            return blobItems.OfType<CloudBlobDirectory>().Any();
         }
 
         /// <summary>

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureBlob/AzureCloudBlobClient.cs

@@ -55,8 +55,7 @@ public Uri BaseUri
 
         public ICloudBlob GetBlobReferenceFromServer(Uri blobUri)
         {
-            var task = _client.GetBlobReferenceFromServerAsync(blobUri);
-            return task.Result;
+            return _client.GetBlobReferenceFromServerAsync(blobUri).GetAwaiter().GetResult();
         }
 
         public ICloudBlobContainer GetContainerReference(string containerName)
@@ -78,15 +77,14 @@ public BlobResultSegment ListBlobsSegmented(
             BlobRequestOptions blobRequestOptions,
             OperationContext operationContext)
         {
-            var task = _client.ListBlobsSegmentedAsync(
+            return _client.ListBlobsSegmentedAsync(
                 prefix,
                 useFlatListing,
                 blobListingDetails,
                 maxResults,
                 continuationToken,
                 blobRequestOptions,
-                operationContext);
-            return task.Result;
+                operationContext).GetAwaiter().GetResult();
         }
 
         public BlobResultSegment ListDirectoryBlobsSegmented(

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureBlob/AzureCloudBlobContainer.cs

@@ -35,8 +35,7 @@ public AzureCloudBlobContainer(CloudBlobContainer container, BlobRequestOptions
 
         public bool CreateIfNotExists()
         {
-            var task = _container.CreateIfNotExistsAsync(_requestOptions, null);
-            return task.Result;
+            return _container.CreateIfNotExistsAsync(_requestOptions, null).GetAwaiter().GetResult();
         }
 
         public void DeleteIfExists()

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureBlob/AzureCloudBlobDirectory.cs

@@ -39,8 +39,13 @@ public ICloudBlobDirectory GetDirectoryReference(string directoryName)
 
         public IEnumerable<IListBlobItem> ListBlobs(bool useFlatListing = false)
         {
-            var task = _directory.ListBlobsSegmentedAsync(useFlatListing, BlobListingDetails.All, null, null, null, null);
-            return task.Result.Results;
+            return _directory.ListBlobsSegmentedAsync(
+                useFlatBlobListing: useFlatListing,
+                BlobListingDetails.All,
+                maxResults: null,
+                null,
+                null,
+                null).GetAwaiter().GetResult().Results;
         }
     }
 }

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureBlob/AzureCloudBlockBlob.cs

@@ -67,7 +67,7 @@ public Stream Open()
         {
             #if REEF_DOTNET_BUILD
                 var task = _blob.OpenReadAsync(null, _requestOptions, null);
-                return task.Result;
+                return task.GetAwaiter().GetResult();
             #else
                 return _blob.OpenRead(null, _requestOptions, null);
             #endif
@@ -76,17 +76,15 @@ public Stream Open()
         public Stream Create()
         {
             #if REEF_DOTNET_BUILD
-                var task = _blob.OpenWriteAsync(null, _requestOptions, null);
-                return task.Result;
+                return _blob.OpenWriteAsync(null, _requestOptions, null).GetAwaiter().GetResult();
             #else
                 return _blob.OpenWrite(null, _requestOptions, null);
             #endif
         }
 
         public bool Exists()
         {
-            var task = _blob.ExistsAsync(_requestOptions, null);
-            return task.Result;
+            return _blob.ExistsAsync(_requestOptions, null).GetAwaiter().GetResult();
         }
 
         public void Delete()
@@ -101,8 +99,7 @@ public void DeleteIfExists()
 
         public string StartCopy(Uri source)
         {
-            var task = _blob.StartCopyAsync(source, null, null, _requestOptions, null);
-            return task.Result;
+            return _blob.StartCopyAsync(source, null, null, _requestOptions, null).GetAwaiter().GetResult();
         }
 
         public void DownloadToFile(string path, FileMode mode)

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureBlob/ICloudBlobClient.cs

@@ -59,7 +59,7 @@ internal interface ICloudBlobClient
         /// Paginates a blob listing with prefix.
         /// </summary>
         BlobResultSegment ListBlobsSegmented(
-            string path,
+            string prefix,
             bool useFlatListing,
             BlobListingDetails blobListingDetails,
             int? maxResults,

lang/cs/Org.Apache.REEF.IO/FileSystem/AzureDataLake/AzureDataLakeFileSystem.cs

@@ -17,6 +17,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Net;
@@ -249,10 +250,10 @@ public Uri CreateUriForPath(string path)
             }
             catch (UriFormatException)
             {
-                resultUri = new Uri(new Uri(this.UriPrefix), path);
+                resultUri = new Uri(new Uri(UriPrefix), path);
             }
 
-            if (!resultUri.AbsoluteUri.StartsWith(this.UriPrefix))
+            if (!resultUri.AbsoluteUri.StartsWith(UriPrefix, true, CultureInfo.InvariantCulture))
             {
                 throw new ArgumentException($"Given URI must begin with valid prefix ({this.UriPrefix})", nameof(path));
             }