Add test case for Tensor.assign #653

The test case is currently not passed yet.

test/TensorFlowNET.UnitTest/Basics/TensorTest.cs

@@ -298,5 +298,45 @@ namespace TensorFlowNET.UnitTest.NativeAPI
 
             tf.compat.v1.disable_eager_execution();
         }
+
+        /// <summary>
+        /// Assign tensor to slice of other tensor.
+        /// </summary>
+        [TestMethod]
+        public void TestAssignOfficial()
+        {
+            // example from https://www.tensorflow.org/api_docs/python/tf/Variable#__getitem__
+
+            // python
+            // import tensorflow as tf
+            // A = tf.Variable([[1,2,3], [4,5,6], [7,8,9]], dtype=tf.float32)
+            // with tf.compat.v1.Session() as sess:
+            //     sess.run(tf.compat.v1.global_variables_initializer())
+            //     print(sess.run(A[:2, :2]))  # => [[1,2], [4,5]]
+
+            //     op = A[:2,:2].assign(22. * tf.ones((2, 2)))
+            //     print(sess.run(op))  # => [[22, 22, 3], [22, 22, 6], [7,8,9]]
+
+            // C#
+            // [[1,2,3], [4,5,6], [7,8,9]]
+            double[][] initial = new double[][]
+            {
+                new double[] { 1, 2, 3 },
+                new double[] { 4, 5, 6 },
+                new double[] { 7, 8, 9 }
+            };
+            Tensor A = tf.Variable(initial, dtype: tf.float32);
+            // Console.WriteLine(A[":2", ":2"]);  // => [[1,2], [4,5]]
+            Tensor result1 = A[":2", ":2"];
+            Assert.IsTrue(Enumerable.SequenceEqual(new double[] { 1, 2 }, result1[0].ToArray<double>()));
+            Assert.IsTrue(Enumerable.SequenceEqual(new double[] { 4, 5 }, result1[1].ToArray<double>()));
+
+            // An unhandled exception of type 'System.ArgumentException' occurred in TensorFlow.NET.dll: 'Dimensions {2, 2,  and {2, 2,  are not compatible'
+            Tensor op = A[":2", ":2"].assign(22.0 * tf.ones((2, 2)));
+            // Console.WriteLine(op);  // => [[22, 22, 3], [22, 22, 6], [7,8,9]]
+            Assert.IsTrue(Enumerable.SequenceEqual(new double[] { 22, 22, 3 }, op[0].ToArray<double>()));
+            Assert.IsTrue(Enumerable.SequenceEqual(new double[] { 22, 22, 6 }, op[1].ToArray<double>()));
+            Assert.IsTrue(Enumerable.SequenceEqual(new double[] { 7,  8,  9 }, op[2].ToArray<double>()));
+        }
     }
 }