Arm backend: Add Deeplab3 test (#8370)

The model causes problems that we see in other models
such as incorrect quantization and int64s showing up.

I'd like to use the model as a case study for improving
what errors we get.

Signed-off-by: Erik Lundell <erik.lundell@arm.com>

backends/arm/test/models/test_dl3_arm.py

@@ -0,0 +1,92 @@
+# Copyright 2025 Arm Limited and/or its affiliates.
+
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+import unittest
+
+import pytest
+
+from executorch.backends.arm.test import common, conftest
+
+from executorch.backends.arm.test.tester.arm_tester import ArmTester
+from executorch.examples.models import deeplab_v3
+
+
+class TestDl3(unittest.TestCase):
+    """Tests DeepLabv3."""
+
+    dl3 = deeplab_v3.DeepLabV3ResNet50Model()
+    model_inputs = dl3.get_example_inputs()
+    dl3 = dl3.get_eager_model()
+
+    @unittest.expectedFailure
+    def test_dl3_tosa_MI(self):
+        (
+            ArmTester(
+                self.dl3,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_tosa_compile_spec("TOSA-0.80+MI"),
+            )
+            .export()
+            .to_edge_transform_and_lower()
+            .to_executorch()
+            .run_method_and_compare_outputs(self.model_inputs)
+        )
+
+    @unittest.expectedFailure
+    def test_dl3_tosa_BI(self):
+        (
+            ArmTester(
+                self.dl3,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_tosa_compile_spec("TOSA-0.80+BI"),
+            )
+            .quantize()
+            .export()
+            .to_edge_transform_and_lower()
+            .to_executorch()
+            .run_method_and_compare_outputs(atol=1.0, qtol=1, inputs=self.model_inputs)
+        )
+
+    @pytest.mark.slow
+    @pytest.mark.corstone_fvp
+    @unittest.skip
+    def test_dl3_u55_BI(self):
+        tester = (
+            ArmTester(
+                self.dl3,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_u55_compile_spec(),
+            )
+            .quantize()
+            .export()
+            .to_edge_transform_and_lower()
+            .to_executorch()
+            .serialize()
+        )
+        if conftest.is_option_enabled("corstone_fvp"):
+            tester.run_method_and_compare_outputs(
+                atol=1.0, qtol=1, inputs=self.model_inputs
+            )
+
+    @pytest.mark.slow
+    @pytest.mark.corstone_fvp
+    @unittest.skip
+    def test_dl3_u85_BI(self):
+        tester = (
+            ArmTester(
+                self.dl3,
+                example_inputs=self.model_inputs,
+                compile_spec=common.get_u85_compile_spec(),
+            )
+            .quantize()
+            .export()
+            .to_edge_transform_and_lower()
+            .to_executorch()
+            .serialize()
+        )
+        if conftest.is_option_enabled("corstone_fvp"):
+            tester.run_method_and_compare_outputs(
+                atol=1.0, qtol=1, inputs=self.model_inputs
+            )