Fixed correct value types when saving columns to a json file (#691)

test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/DataStorage/SaveAsJsonFileStreamWriterTests.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 //
 
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
@@ -142,5 +143,59 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.DataStorage
                 }
             }
         }
+
+        [Fact]
+        public void WriteRowWithSpecialTypesSuccess()
+        {
+
+            // Setup:
+            // ... Create a request params that has three different types of value
+            // ... Create a set of data to write
+            // ... Create storage for the output
+            SaveResultsAsJsonRequestParams saveParams = new SaveResultsAsJsonRequestParams();
+            List<DbCellValue> data = new List<DbCellValue>
+            {
+                new DbCellValue {DisplayValue = "1", RawObject = 1},
+                new DbCellValue {DisplayValue = "1.234", RawObject = 1.234},
+                new DbCellValue {DisplayValue = "2017-07-08T00:00:00", RawObject = new DateTime(2017, 07, 08)},
+                
+            };
+            List<DbColumnWrapper> columns = new List<DbColumnWrapper>
+            {
+                new DbColumnWrapper(new TestDbColumn("numberCol", typeof(int))),
+                new DbColumnWrapper(new TestDbColumn("decimalCol", typeof(decimal))),
+                new DbColumnWrapper(new TestDbColumn("datetimeCol", typeof(DateTime)))
+            };
+            byte[] output = new byte[8192];
+
+            // If:
+            // ... I write two rows
+            var jsonWriter = new SaveAsJsonFileStreamWriter(new MemoryStream(output), saveParams);
+            using (jsonWriter)
+            {
+                jsonWriter.WriteRow(data, columns);
+                jsonWriter.WriteRow(data, columns);
+            }
+
+            // Then:
+            // ... Upon deserialization to an array of dictionaries
+            string outputString = Encoding.UTF8.GetString(output).TrimEnd('\0');
+            Dictionary<string, string>[] outputObject =
+                JsonConvert.DeserializeObject<Dictionary<string, string>[]>(outputString);
+
+            // ... There should be 2 items in the array,
+            // ... The item should have three fields, and three values, assigned appropriately
+            // ... The deserialized values should match the display value
+            Assert.Equal(2, outputObject.Length);
+            foreach (var item in outputObject)
+            {
+                Assert.Equal(3, item.Count);
+                for (int i = 0; i < columns.Count; i++)
+                {
+                    Assert.True(item.ContainsKey(columns[i].ColumnName));
+                    Assert.Equal(data[i].RawObject == null ? null : data[i].DisplayValue, item[columns[i].ColumnName]);
+                }
+            }
+        }
     }
 }