Added back a test for 'Tensor.init(stacking:alongAxis:)'. (#466)

Author: eaplatanios

Tests/TensorFlowTests/TensorAutoDiffTests.swift

@@ -153,18 +153,17 @@ final class TensorAutoDiffTests: XCTestCase {
         XCTAssertEqual(varianceGradAlongAxes(input), expected)
     }
 
-    // TODO: Uncomment once TF-653 is resolved.
-    // func testTensorInitStacking() {
-    //     let a1 = Tensor<Float>([1, 2, 3, 4, 5])
-    //     let b1 = Tensor<Float>([6, 7, 8, 9, 10])
-    //     let a2 = Tensor<Float>([1, 1, 1, 1, 1])
-    //     let b2 = Tensor<Float>([1, 1, 1, 1, 1])
-    //     let grads = gradient(at: a2, b2) { a, b in
-    //         Tensor<Float>(stacking: [a1 * a, b1 * b], alongAxis: -1).sum()
-    //     }
-    //     XCTAssertEqual(a1, grads.0)
-    //     XCTAssertEqual(b1, grads.1)
-    // }
+    func testTensorInitStacking() {
+        let a1 = Tensor<Float>([1, 2, 3, 4, 5])
+        let b1 = Tensor<Float>([6, 7, 8, 9, 10])
+        let a2 = Tensor<Float>([1, 1, 1, 1, 1])
+        let b2 = Tensor<Float>([1, 1, 1, 1, 1])
+        let grads = gradient(at: a2, b2) { a, b in
+            Tensor<Float>(stacking: [a1 * a, b1 * b], alongAxis: -1).sum()
+        }
+        XCTAssertEqual(a1, grads.0)
+        XCTAssertEqual(b1, grads.1)
+    }
 
     func testExpandingShape() {
         func f1(a: Tensor<Float>) -> Tensor<Float> { a.expandingShape(at: 0).squared() }
@@ -448,8 +447,7 @@ final class TensorAutoDiffTests: XCTestCase {
         ("testSum", testSum),
         ("testMean", testMean),
         ("testVariance", testVariance),
-        // TODO: Uncomment once TF-653 is resolved.
-        // ("testTensorInitStacking", testTensorInitStacking),
+        ("testTensorInitStacking", testTensorInitStacking),
         ("testExpandingShape", testExpandingShape),
         ("testSqueezingShape", testSqueezingShape),
         ("testReshapedBackprop", testReshapedBackprop),