twister: Add configuration reader to pytest-twister-harness

Added a class that helps to read Kconfigs from a configuration file.

Signed-off-by: Lukasz Fundakowski <[email protected]>

Author: fundakol

scripts/pylib/pytest-twister-harness/src/twister_harness/fixtures.py

@@ -4,7 +4,7 @@
 
 import logging
 from pathlib import Path
-from typing import Generator, Type
+from typing import Generator, Type, Callable
 
 import pytest
 import time
@@ -15,6 +15,7 @@
 from twister_harness.helpers.shell import Shell
 from twister_harness.helpers.mcumgr import MCUmgr, MCUmgrBle
 from twister_harness.helpers.utils import find_in_config
+from twister_harness.helpers.config_reader import ConfigReader
 
 logger = logging.getLogger(__name__)
 
@@ -117,3 +118,27 @@ def mcumgr_ble(device_object: DeviceAdapter) -> Generator[MCUmgrBle, None, None]
     ) or 'Zephyr'
 
     yield MCUmgrBle.create_for_ble(hci_index, peer_name)
+
+
+@pytest.fixture
+def config_reader() -> Callable[[str | Path], ConfigReader]:
+    """
+    Pytest fixture that provides a ConfigReader instance for reading configuration files.
+
+    This fixture allows tests to easily create a ConfigReader object by passing
+    the path to a configuration file. The ConfigReader reads the file and
+    provides a method to access the configuration data.
+
+    Returns:
+        Callable[[str, Path], ConfigReader]: A function that takes a file path
+        (as a string or Path object) and returns an instance of ConfigReader.
+
+    Example:
+        def test_config_value(config_reader):
+            config = config_reader("build_dir/zephyr/.config")
+            assert config.read("some_key") == "expected_value"
+    """
+    def inner(file):
+        return ConfigReader(file)
+
+    return inner

scripts/pylib/pytest-twister-harness/src/twister_harness/helpers/config_reader.py

@@ -0,0 +1,103 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Implementation for a configuration file reader."""
+
+import logging
+import os
+import re
+from pathlib import Path
+from typing import Any
+
+__tracebackhide__ = True
+
+logger = logging.getLogger(__name__)
+
+
+class ConfigReader:
+    """Reads configuration from a config file."""
+
+    def __init__(self, config_file: Path | str) -> None:
+        """Initialize.
+
+        :param config_file: path to a configuration file
+        """
+        assert os.path.exists(config_file), f"Path does not exist: {config_file}"
+        assert os.path.isfile(config_file), f"It is not a file: {config_file}"
+        self.config_file = config_file
+        self.config: dict[str, str] = {}
+        self.parse()
+
+    def parse(self) -> dict[str, str]:
+        """Parse a config file."""
+        pattern = re.compile(r"^(?P<key>.+)=(?P<value>.+)$")
+        with open(self.config_file) as file:
+            for line in file:
+                if match := pattern.match(line):
+                    key, value = match.group("key"), match.group("value")
+                    self.config[key] = value.strip("\"'")
+        return self.config
+
+    def read(self, config_key: str, default: Any = None, *, silent=False) -> str | None:
+        """Find key in config file.
+
+        :param config_key: key to read
+        :param default: default value to return if key not found
+        :param silent: do not raise an exception when key not found
+        :raises ValueError: if key not found
+        """
+        try:
+            value = self.config[config_key]
+        except KeyError:
+            if default is not None:
+                return default
+            logger.debug("Not found key: %s", config_key)
+            if silent:
+                return None
+            raise ValueError(f"Could not find key: {config_key}") from None
+        logger.debug("Found matching key: %s=%s", config_key, value)
+        return value
+
+    def read_int(self, config_key: str, default: int | None = None) -> int:
+        """Find key in config file and return int.
+
+        :param config_key: key to read
+        :param default: default value to return if key not found
+        """
+        if default is not None and not isinstance(default, int):
+            raise TypeError(f"default value must be type of int, but was {type(default)}")
+        if default is not None:
+            default = hex(default)  # type: ignore
+        if value := self.read(config_key, default):
+            try:
+                return int(value)
+            except ValueError:
+                return int(value, 16)
+        raise Exception("Non reachable code")  # pragma: no cover
+
+    def read_bool(self, config_key: str, default: bool | None = None) -> bool:
+        """Find key in config file and return bool.
+
+        :param config_key: key to read
+        :param default: default value to return if key not found
+        """
+        value = self.read(config_key, default)
+        if isinstance(value, str):
+            if value.lower() == "y":
+                return True
+            if value.lower() == "n":
+                return False
+        return bool(value)
+
+    def read_hex(self, config_key: str, default: int | None = None) -> str:
+        """Find key in config file and return hex.
+
+        :param config_key: key to read
+        :param default: default value to return if key not found
+        :return: hex value as string
+        """
+        if default is not None and not isinstance(default, int):
+            raise TypeError(f"default value must be type of int, but was {type(default)}")
+        value = self.read_int(config_key, default)
+        return hex(value)

scripts/pylib/pytest-twister-harness/tests/helpers/test_config_reader.py

@@ -0,0 +1,81 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import textwrap
+
+import pytest
+from twister_harness.helpers.config_reader import ConfigReader
+
+CONFIG: str = textwrap.dedent("""
+    # comment
+    X_PM_MCUBOOT_OFFSET=0x0
+    X_PM_MCUBOOT_END_ADDRESS=0xd800
+
+    X_PM_MCUBOOT_NAME=mcuboot
+    X_PM_MCUBOOT_ID=0
+    X_CONFIG_BOOL_TRUE=y
+    X_CONFIG_BOOL_FALSE=n
+""")
+
+
+@pytest.fixture
+def config_reader(tmp_path) -> ConfigReader:
+    config_file = tmp_path / "config"
+    config_file.write_text(CONFIG)
+    reader = ConfigReader(config_file)
+    return reader
+
+
+def test_if_raises_exception_path_is_directory(tmp_path):
+    build_dir = tmp_path / "build"
+    build_dir.mkdir()
+    with pytest.raises(AssertionError, match=f"It is not a file: {build_dir}"):
+        ConfigReader(build_dir)
+
+
+def test_if_raises_exception_when_path_does_not_exist(tmp_path):
+    build_dir = tmp_path / "build"
+    build_dir.mkdir()
+    config_file = build_dir / "file_does_not_exist"
+    with pytest.raises(AssertionError, match=f"Path does not exist: {config_file}"):
+        ConfigReader(config_file)
+
+
+def test_if_can_read_values_from_config_file(config_reader):
+    assert config_reader.config, "Config is empty"
+    assert config_reader.read("X_PM_MCUBOOT_NAME") == "mcuboot"
+    assert config_reader.read("X_CONFIG_BOOL_TRUE") == "y"
+    assert config_reader.read_bool("X_CONFIG_BOOL_TRUE") is True
+    assert config_reader.read_bool("X_CONFIG_BOOL_FALSE") is False
+    assert config_reader.read_hex("X_PM_MCUBOOT_END_ADDRESS") == "0xd800"
+    assert config_reader.read_int("X_PM_MCUBOOT_END_ADDRESS") == 0xD800
+
+
+def test_if_raises_value_error_when_key_does_not_exist(config_reader):
+    with pytest.raises(ValueError, match="Could not find key: DO_NOT_EXIST"):
+        config_reader.read("DO_NOT_EXIST")
+
+    with pytest.raises(ValueError, match="Could not find key: DO_NOT_EXIST"):
+        config_reader.read_int("DO_NOT_EXIST")
+
+
+def test_if_raises_value_error_when_default_value_is_not_proper(config_reader):
+    with pytest.raises(TypeError, match="default value must be type of int, but was .*"):
+        config_reader.read_hex("X_PM_MCUBOOT_OFFSET", "0x10")
+    with pytest.raises(TypeError, match="default value must be type of int, but was .*"):
+        config_reader.read_int("X_PM_MCUBOOT_OFFSET", "0x10")
+
+
+def test_if_returns_default_value_when_key_does_not_exist(config_reader):
+    assert config_reader.read("DO_NOT_EXIST", "default") == "default"
+    assert config_reader.read_int("DO_NOT_EXIST", 10) == 10
+    assert config_reader.read_hex("DO_NOT_EXIST", 0x20) == "0x20"
+    assert config_reader.read_bool("DO_NOT_EXIST", True) is True
+    assert config_reader.read_bool("DO_NOT_EXIST", False) is False
+    assert config_reader.read_bool("DO_NOT_EXIST", 1) is True
+    assert config_reader.read_bool("DO_NOT_EXIST", "1") is True
+
+
+def test_if_does_not_raise_exception_in_silent_mode_for_key_not_found(config_reader):
+    assert config_reader.read("DO_NOT_EXIST", silent=True) is None