@Test
    public void testEmpty() {
        TensorType type = new TensorType.Builder().mapped("x").indexed("y", 3).build();
        Tensor empty = Tensor.Builder.of(type).build();
        assertTrue(empty instanceof MixedTensor);
        assertTrue(empty.isEmpty());
        assertEquals("tensor(x{},y[3]):{}", empty.toString());
        assertEquals("tensor(x{},y[3]):{}", Tensor.from("tensor(x{},y[3]):{}").toString());
    }
Basic mixed tensor tests. Tensor operations are tested in EvaluationTestCase

@author lesters
vespajlib/src/test/java/com/yahoo/tensor/MixedTensorTestCase.java