IVGCVSW-5571 Expose the TfLite Delegate to the TfLite python API

 * Implemented external delegate adaptor interface for TfLite
 * Activated armnn logging for delegate
 * Added logging info to indicate if gpu tuning is turned on
 * Added pytests to ensure functionality of the external delegate adaptor
 * Included the delegate directory into doxygen
 * Added documentation on how to use the external delegate in python

Signed-off-by: Finn Williams <Finn.Williams@arm.com>
Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Change-Id: Id3b4588fb0b9ac7e3f47ba2c19feead7beb58e18

5 files changed, 128 insertions, 0 deletions

diff --git a/delegate/python/test/conftest.py b/delegate/python/test/conftest.py
new file mode 100644
index 0000000000..780a0492e1
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+++ b/delegate/python/test/conftest.py
@@ -0,0 +1,30 @@
+# Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+# SPDX-License-Identifier: MIT
+import pytest
+import os
+
+
+@pytest.fixture(scope="module")
+def test_data_folder(request):
+    """
+    This fixture returns path to the folder with the shared test resources
+    """
+    return str(os.path.join(request.fspath.dirname, "test_data"))
+
+
+def pytest_addoption(parser):
+    """
+    Adds the program option 'delegate-dir' to pytest
+    """
+    parser.addoption("--delegate-dir",
+                     action="append",
+                     help="Directory of the armnn tflite delegate library",
+                     required=True)
+
+
+def pytest_generate_tests(metafunc):
+    """
+    Makes the program option 'delegate-dir' available to all tests as a function fixture
+    """
+    if "delegate_dir" in metafunc.fixturenames:
+        metafunc.parametrize("delegate_dir", metafunc.config.getoption("delegate_dir"))
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diff --git a/delegate/python/test/pytest.ini b/delegate/python/test/pytest.ini
new file mode 100644
index 0000000000..719af3ce05
--- /dev/null
+++ b/delegate/python/test/pytest.ini
@@ -0,0 +1,9 @@
+# Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+# SPDX-License-Identifier: MIT
+
+[pytest]
+addopts = --strict-markers
+markers =
+    CpuRefTest: marks tests that require the CpuRef backend
+    CpuAccTest: marks tests that require the CpuAcc backend
+    GpuAccTest: marks tests that require the GpuAcc backend
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diff --git a/delegate/python/test/test_data/mock_model.tflite b/delegate/python/test/test_data/mock_model.tflite
new file mode 100644
index 0000000000..0b8944d3ed
--- /dev/null
+++ b/delegate/python/test/test_data/mock_model.tflite
diff --git a/delegate/python/test/test_external_delegate.py b/delegate/python/test/test_external_delegate.py
new file mode 100644
index 0000000000..995de8cd70
--- /dev/null
+++ b/delegate/python/test/test_external_delegate.py
@@ -0,0 +1,65 @@
+# Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+# SPDX-License-Identifier: MIT
+
+import pytest
+import tflite_runtime.interpreter as tflite
+import os
+from utils import run_mock_model
+
+
+def test_external_delegate_unknown_options(delegate_dir):
+    print(delegate_dir)
+    with pytest.raises(ValueError):
+        tflite.load_delegate(
+            delegate_dir,
+            options={"wrong": "wrong"})
+
+
+def test_external_delegate_options_multiple_backends(delegate_dir):
+    tflite.load_delegate(
+        delegate_dir,
+        options={"backends": "GpuAcc,CpuAcc,CpuRef,Unknown"})
+
+
+@pytest.mark.GpuAccTest
+def test_external_delegate_options_gpu_tuning(delegate_dir, test_data_folder, tmp_path):
+
+    tuning_file = os.path.join(str(tmp_path), "test_gpu.tuning")
+    # cleanup previous test run if necessary
+    if os.path.exists(tuning_file):
+        os.remove(tuning_file)
+
+    # with tuning level 2 a tuning file should be created
+    armnn_delegate = tflite.load_delegate(
+        delegate_dir,
+        options={
+            "backends": "GpuAcc",
+            "gpu-tuning-level": "2",
+            "gpu-tuning-file": tuning_file,
+            "logging-severity": "info"})
+
+    run_mock_model(armnn_delegate, test_data_folder)
+
+    # destroy delegate, otherwise tuning file won't be written to file
+    armnn_delegate.__del__()
+    assert (os.path.exists(tuning_file))
+
+    # if no tuning level is provided it defaults to 0 which means it will use the tuning parameters from a tuning
+    # file if one is provided
+    armnn_delegate2 = tflite.load_delegate(
+        delegate_dir,
+        options={
+            "backends": "GpuAcc",
+            "gpu-tuning-file": tuning_file,
+            "logging-severity": "info"})
+
+    run_mock_model(armnn_delegate2, test_data_folder)
+
+    # cleanup
+    os.remove(tuning_file)
+
+def test_external_delegate_options_wrong_logging_level(delegate_dir):
+    with pytest.raises(ValueError):
+        tflite.load_delegate(
+            delegate_dir,
+            options={"logging-severity": "wrong"})
diff --git a/delegate/python/test/utils.py b/delegate/python/test/utils.py
new file mode 100644
index 0000000000..3adc24fe35
--- /dev/null
+++ b/delegate/python/test/utils.py
@@ -0,0 +1,24 @@
+# Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+# SPDX-License-Identifier: MIT
+
+import tflite_runtime.interpreter as tflite
+import numpy as np
+import os
+
+
+def run_mock_model(delegate, test_data_folder):
+    model_path = os.path.join(test_data_folder, 'mock_model.tflite')
+    interpreter = tflite.Interpreter(model_path=model_path,
+                                     experimental_delegates=[delegate])
+    interpreter.allocate_tensors()
+
+    # Get input and output tensors.
+    input_details = interpreter.get_input_details()
+    output_details = interpreter.get_output_details()
+
+    # Test model on random input data.
+    input_shape = input_details[0]['shape']
+    input_data = np.array(np.random.random_sample(input_shape), dtype=np.uint8)
+    interpreter.set_tensor(input_details[0]['index'], input_data)
+
+    interpreter.invoke()
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