tf.layers.flatten: Added and fixed special unit-test case.

src/TensorFlowNET.Core/APIs/tf.layers.cs

@@ -196,8 +196,7 @@ namespace Tensorflow
                     inputs = array_ops.transpose(inputs, premutation.ToArray());
                 }
 
-                var ret = array_ops.reshape(inputs, new int[] {input_shape[0], -1});
-                ret.shape = ret.shape;
+                var ret = array_ops.reshape(inputs, compute_output_shape(input_shape));
                 //ret.set_shape(compute_output_shape(ret.shape));
                 return ret;
 

test/TensorFlowNET.UnitTest/layers_test/flatten.cs

@@ -45,5 +45,14 @@ namespace TensorFlowNET.UnitTest.layers_test
             var input = tf.placeholder(TF_DataType.TF_INT32, new TensorShape(3, 4, None, 1, 2));
             sess.run(tf.layers.flatten(input), (input, np.arange(3 * 4 * 3 * 1 * 2).reshape(3, 4, 3, 1, 2))).Should().BeShaped(3, 24);
         }
+
+        [TestMethod]
+        public void Case5()
+        {
+            var sess = tf.Session().as_default();
+
+            var input = tf.placeholder(TF_DataType.TF_INT32, new TensorShape(None, 4, 3, 1, 2));
+            sess.run(tf.layers.flatten(input), (input, np.arange(3 * 4 * 3 * 1 * 2).reshape(3, 4, 3, 1, 2))).Should().BeShaped(3, 24);
+        }
     }
 }