Fix dataset_cardinality for dataset map.

Author: Oceania2018

src/TensorFlowNET.Core/Data/IDatasetV2.cs

@@ -57,7 +57,7 @@ public interface IDatasetV2 : IEnumerable<(Tensor, Tensor)>
 
         IDatasetV2 map(Func<Tensor, Tensor> map_func,
             bool use_inter_op_parallelism = true,
-            bool preserve_cardinality = false,
+            bool preserve_cardinality = true,
             bool use_legacy_function = false);
 
         IDatasetV2 map(Func<Tensor, (Tensor, Tensor), (Tensor, Tensor)> map_func,

src/TensorFlowNET.Core/Data/MapDataset.cs

@@ -25,7 +25,9 @@ public MapDataset(IDatasetV2 input_dataset,
             variant_tensor = ops.map_dataset(input_dataset.variant_tensor,
                 func,
                 output_types,
-                output_shapes);
+                output_shapes,
+                use_inter_op_parallelism: use_inter_op_parallelism,
+                preserve_cardinality: preserve_cardinality);
         }
     }
 }

test/TensorFlowNET.UnitTest/Dataset/DatasetTest.cs

@@ -143,7 +143,7 @@ public void Cache()
             }
         }
 
-        [TestMethod, Ignore]
+        [TestMethod]
         public void Cardinality()
         {
             var dataset = tf.data.Dataset.range(10);