add hidden column test

dlegate metadata construction to common ctor from crypto ctor

Author: Wraith2

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/AlwaysEncryptedHelperClasses.cs

@@ -234,13 +234,9 @@ sealed internal partial class _SqlMetaDataSet
         internal readonly SqlTceCipherInfoTable? cekTable; // table of "column encryption keys" used for this metadataset
 
         internal _SqlMetaDataSet(int count, SqlTceCipherInfoTable? cipherTable)
+            : this(count)
         {
             cekTable = cipherTable;
-            _metaDataArray = new _SqlMetaData[count];
-            for (int i = 0; i < _metaDataArray.Length; ++i)
-            {
-                _metaDataArray[i] = new _SqlMetaData(i);
-            }
         }
     }
 

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

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Collections.Generic;
 using System.Data;
 using System.Text;
@@ -225,5 +226,81 @@ private static bool IsColumnBitSet(SqlConnection con, string selectQuery, int in
             }
             return columnSetPresent;
         }
+
+        [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
+        public static void CheckHiddenColumns()
+        {
+            // hidden columns can be found by using CommandBehavious.KeyInfo or at the sql level
+            // by using the FOR BROWSE option. These features return the column information requested and
+            // also include any key information required to be able to find the row containing the data
+            // requested. The additional key infomration is provided as hidden columns and can be seen using
+            // the difference between VisibleFieldCount and FieldCount on the reader
+
+            string tempTableName = DataTestUtility.GenerateObjectName();
+
+            string createQuery = $@"
+create table [{tempTableName}] (
+	user_id int not null identity(1,1),
+	first_name varchar(100) null,
+	last_name varchar(100) null);
+
+alter table [{tempTableName}] add constraint pk_{tempTableName}_user_id primary key (user_id);
+
+insert into [{tempTableName}] (first_name,last_name) values ('Joe','Smith')
+";
+
+            string dataQuery = $@"select first_name, last_name from [{tempTableName}]";
+
+
+            int fieldCount = 0;
+            int visibleFieldCount = 0;
+            Type[] types = null;
+            string[] names = null;
+
+            using (SqlConnection connection = new SqlConnection(DataTestUtility.TCPConnectionString))
+            {
+                connection.Open();
+
+                try
+                {
+                    using (SqlCommand createCommand = new SqlCommand(createQuery, connection))
+                    {
+                        createCommand.ExecuteNonQuery();
+                    }
+
+                    using (SqlCommand queryCommand = new SqlCommand(dataQuery, connection))
+                    {
+                        using (SqlDataReader reader = queryCommand.ExecuteReader(CommandBehavior.KeyInfo))
+                        {
+                            fieldCount = reader.FieldCount;
+                            visibleFieldCount = reader.VisibleFieldCount;
+                            types = new Type[fieldCount];
+                            names = new string[fieldCount];
+                            for (int index = 0; index < fieldCount; index++)
+                            {
+                                types[index] = reader.GetFieldType(index);
+                                names[index] = reader.GetName(index);
+                            }
+                        }
+                    }
+                }
+                finally
+                {
+                    DataTestUtility.DropTable(connection, tempTableName);
+                }
+            }
+
+            Assert.Equal(3, fieldCount);
+            Assert.Equal(2, visibleFieldCount);
+            Assert.NotNull(types);
+            Assert.NotNull(names);
+
+            // requested fields
+            Assert.Contains("first_name", names, StringComparer.Ordinal);
+            Assert.Contains("last_name", names, StringComparer.Ordinal);
+
+            // hidden field
+            Assert.Contains("user_id", names, StringComparer.Ordinal);
+        }
     }
 }