scripts: pytest: add pytester tests

Add tests which use pytester to call pytest with pytest-twister-harness
plugin on previously defined test. This gives a possibility to test
plugin in end-to-end variant.

Signed-off-by: Piotr Golyzniak <piotr.golyzniak@nordicsemi.no>

scripts/pylib/pytest-twister-harness/tests/conftest.py

@@ -2,12 +2,13 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+from __future__ import annotations
+
+import os
 from pathlib import Path
 
 import pytest
 
-# pytest_plugins = ['pytester']
-
 
 @pytest.fixture
 def resources(request: pytest.FixtureRequest) -> Path:
@@ -15,9 +16,17 @@ def resources(request: pytest.FixtureRequest) -> Path:
     return Path(request.module.__file__).parent.joinpath('data')
 
 
-@pytest.fixture(scope='function')
-def copy_example(pytester) -> Path:
-    """Copy example tests to temporary directory and return path the temp directory."""
-    resources_dir = Path(__file__).parent / 'data'
-    pytester.copy_example(str(resources_dir))
-    return pytester.path
+@pytest.fixture
+def zephyr_base() -> str:
+    zephyr_base_path = os.getenv('ZEPHYR_BASE')
+    if zephyr_base_path is None:
+        pytest.fail('Environmental variable ZEPHYR_BASE has to be set.')
+    else:
+        return zephyr_base_path
+
+
+@pytest.fixture
+def twister_harness(zephyr_base) -> str:
+    """Retrun path to pytest-twister-harness src directory"""
+    pytest_twister_harness_path = str(Path(zephyr_base) / 'scripts' / 'pylib' / 'pytest-twister-harness' / 'src')
+    return pytest_twister_harness_path

scripts/pylib/pytest-twister-harness/tests/plugin_test.py

@@ -0,0 +1,59 @@
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import os
+import textwrap
+from pathlib import Path
+
+import pytest
+
+pytest_plugins = ['pytester']
+
+
+@pytest.mark.parametrize(
+    'import_path, class_name, device_type',
+    [
+        ('twister_harness.device.binary_adapter', 'NativeSimulatorAdapter', 'native'),
+        ('twister_harness.device.qemu_adapter', 'QemuAdapter', 'qemu'),
+        ('twister_harness.device.hardware_adapter', 'HardwareAdapter', 'hardware'),
+    ],
+    ids=[
+        'native',
+        'qemu',
+        'hardware',
+    ]
+)
+def test_if_adapter_is_chosen_properly(
+    import_path: str,
+    class_name: str,
+    device_type: str,
+    tmp_path: Path,
+    twister_harness: str,
+    pytester: pytest.Pytester,
+):
+    pytester.makepyfile(
+        textwrap.dedent(
+            f"""
+            from twister_harness import DeviceAdapter
+            from {import_path} import {class_name}
+
+            def test_plugin(device_object):
+                assert isinstance(device_object, DeviceAdapter)
+                assert type(device_object) == {class_name}
+            """
+        )
+    )
+
+    build_dir = tmp_path / 'build_dir'
+    os.mkdir(build_dir)
+    pytester.syspathinsert(twister_harness)
+    result = pytester.runpytest(
+        '--twister-harness',
+        f'--build-dir={build_dir}',
+        f'--device-type={device_type}',
+        '-p', 'twister_harness.plugin'
+    )
+
+    assert result.ret == 0
+    result.assert_outcomes(passed=1, failed=0, errors=0, skipped=0)