Adding tests old lowering flow for op_abs.py

Summary: Added tests with the legacy mode.

Differential Revision: D65542758

Author: ru-m8

backends/xnnpack/test/ops/abs.py

@@ -32,6 +32,20 @@ def _test_abs(self, inputs):
             .run_method_and_compare_outputs()
         )
 
+    def _test_abs_legacy_mode(self, inputs):
+        (
+            Tester(self.Abs(), inputs)
+            .export()
+            .check_count({"torch.ops.aten.abs.default": 1})
+            .to_edge()
+            .partition()
+            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            .check_not(["executorch_exir_dialects_edge__ops_aten_abs_default"])
+            .to_executorch()
+            .serialize()
+            .run_method_and_compare_outputs()
+        )
+
     def test_fp16_abs(self):
         inputs = (
             torch.Tensor(
@@ -43,6 +57,17 @@ def test_fp16_abs(self):
         )
         self._test_abs(inputs)
 
+    def test_fp16_abs_legacy_mode(self):
+        inputs = (
+            torch.Tensor(
+                [
+                    [0.0, 0.1, 0.5, 0.499],
+                    [-0.6, -0.4, 100.1, -1000.1],
+                ],
+            ).to(torch.float16),
+        )
+        self._test_abs_legacy_mode(inputs)
+
     def test_fp32_abs(self):
         inputs = (
             torch.Tensor(
@@ -53,3 +78,14 @@ def test_fp32_abs(self):
             ),
         )
         self._test_abs(inputs)
+
+    def test_fp32_abs_legacy_mode(self):
+        inputs = (
+            torch.Tensor(
+                [
+                    [0.0, 0.1, 0.5, 0.499],
+                    [-0.6, -0.4, 100.1, -1000.1],
+                ],
+            ),
+        )
+        self._test_abs_legacy_mode(inputs)