Revert "Fix sequential text reader bug and add covering test (#3383)"

This reverts commit 97be747.

Author: samsharma2700

src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlSequentialTextReader.cs

@@ -172,7 +172,7 @@ public override Task<int> ReadAsync(char[] buffer, int index, int count)
                         byte[] byteBuffer = PrepareByteBuffer(charsNeeded, out int byteBufferUsed);
 
                         // Permit a 0 byte read in order to advance the reader to the correct column
-                        if (byteBufferUsed <= byteBuffer.Length || byteBuffer.Length == 0)
+                        if ((byteBufferUsed < byteBuffer.Length) || (byteBuffer.Length == 0))
                         {
                             SqlDataReader reader = _reader;
                             if (reader != null)

src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/DataReaderTest/DataReaderTest.cs

@@ -593,60 +593,6 @@ integrated into a comprehensive development
             }
         }
 
-        [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
-        public static async Task CanReadSequentialDecreasingChunks()
-        {
-            // pattern repeat input allows you to more easily identify if chunks are incorrectly
-            //  related to each other by seeing the start and end of sequential chunks and checking
-            //  if they correctly move to the next char while debugging
-            // simply repeating a single char can't tell you where in the string it went wrong.
-            const string baseString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-            StringBuilder inputBuilder = new StringBuilder();
-            while (inputBuilder.Length < (64 * 1024))
-            {
-                inputBuilder.Append(baseString);
-                inputBuilder.Append(' ');
-            }
-
-            string input = inputBuilder.ToString();
-
-            StringBuilder resultBuilder = new StringBuilder();
-            CancellationTokenSource cts = new CancellationTokenSource();
-            using (var connection = new SqlConnection(DataTestUtility.TCPConnectionString))
-            {
-                await connection.OpenAsync(cts.Token);
-
-                using (var command = connection.CreateCommand())
-                {
-                    command.CommandText = "SELECT CONVERT(varchar(max),@str) as a";
-                    command.Parameters.AddWithValue("@str", input);
-
-                    using (var reader = await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess, cts.Token))
-                    {
-                        if (await reader.ReadAsync(cts.Token))
-                        {
-                            using (var textReader = reader.GetTextReader(0))
-                            {
-                                var buffer = new char[4096];
-                                var charsReadCount = -1;
-                                var start = 0;
-                                while (charsReadCount != 0)
-                                {
-                                    charsReadCount = await textReader.ReadAsync(buffer, start, buffer.Length - start);
-                                    resultBuilder.Append(buffer, start, charsReadCount);
-                                    start++;
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-
-            string result = resultBuilder.ToString();
-
-            Assert.Equal(input, result);
-        }
-
         [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
         public static async Task CanReadBinaryData()
         {