feat(anta): Add get_item function (aristanetworks#518)

anta/tools/get_item.py

@@ -0,0 +1,83 @@
+# Copyright (c) 2023-2024 Arista Networks, Inc.
+# Use of this source code is governed by the Apache License 2.0
+# that can be found in the LICENSE file.
+
+"""Get one dictionary from a list of dictionaries by matching the given key and value."""
+from __future__ import annotations
+
+from typing import Any, Optional
+
+
+# pylint: disable=too-many-arguments
+def get_item(
+    list_of_dicts: list[dict[Any, Any]],
+    key: Any,
+    value: Any,
+    default: Optional[Any] = None,
+    required: bool = False,
+    case_sensitive: bool = False,
+    var_name: Optional[str] = None,
+    custom_error_msg: Optional[str] = None,
+) -> Any:
+    """Get one dictionary from a list of dictionaries by matching the given key and value.
+
+    Returns the supplied default value or None if there is no match and "required" is False.
+
+    Will return the first matching item if there are multiple matching items.
+
+    Parameters
+    ----------
+    list_of_dicts : list(dict)
+        List of Dictionaries to get list item from
+    key : any
+        Dictionary Key to match on
+    value : any
+        Value that must match
+    default : any
+        Default value returned if the key and value is not found
+    required : bool
+        Fail if there is no match
+    case_sensitive : bool
+        If the search value is a string, the comparison will ignore case by default
+    var_name : str
+        String used for raising exception with the full variable name
+    custom_error_msg : str
+        Custom error message to raise when required is True and the value is not found
+
+    Returns
+    -------
+    any
+        Dict or default value
+
+    Raises
+    ------
+    ValueError
+        If the key and value is not found and "required" == True
+    """
+    if var_name is None:
+        var_name = key
+
+    if (not isinstance(list_of_dicts, list)) or list_of_dicts == [] or value is None or key is None:
+        if required is True:
+            raise ValueError(custom_error_msg or var_name)
+        return default
+
+    for list_item in list_of_dicts:
+        if not isinstance(list_item, dict):
+            # List item is not a dict as required. Skip this item
+            continue
+
+        item_value = list_item.get(key)
+
+        # Perform case-insensitive comparison if value and item_value are strings and case_sensitive is False
+        if not case_sensitive and isinstance(value, str) and isinstance(item_value, str):
+            if item_value.casefold() == value.casefold():
+                return list_item
+        elif item_value == value:
+            # Match. Return this item
+            return list_item
+
+    # No Match
+    if required is True:
+        raise ValueError(custom_error_msg or var_name)
+    return default

tests/units/tools/test_get_item.py

@@ -0,0 +1,72 @@
+# Copyright (c) 2023-2024 Arista Networks, Inc.
+# Use of this source code is governed by the Apache License 2.0
+# that can be found in the LICENSE file.
+
+"""Tests for `anta.tools.get_item`."""
+from __future__ import annotations
+
+from contextlib import nullcontext as does_not_raise
+from typing import Any
+
+import pytest
+
+from anta.tools.get_item import get_item
+
+DUMMY_DATA = [
+    ("id", 0),
+    {
+        "id": 1,
+        "name": "Alice",
+        "age": 30,
+        "email": "[email protected]",
+    },
+    {
+        "id": 2,
+        "name": "Bob",
+        "age": 35,
+        "email": "[email protected]",
+    },
+    {
+        "id": 3,
+        "name": "Charlie",
+        "age": 40,
+        "email": "[email protected]",
+    },
+]
+
+
+@pytest.mark.parametrize(
+    "list_of_dicts, key, value, default, required, case_sensitive, var_name, custom_error_msg, expected_result, expected_raise",
+    [
+        pytest.param([], "name", "Bob", None, False, False, None, None, None, does_not_raise(), id="empty list"),
+        pytest.param([], "name", "Bob", None, True, False, None, None, None, pytest.raises(ValueError, match="name"), id="empty list and required"),
+        pytest.param(DUMMY_DATA, "name", "Jack", None, False, False, None, None, None, does_not_raise(), id="missing item"),
+        pytest.param(DUMMY_DATA, "name", "Alice", None, False, False, None, None, DUMMY_DATA[1], does_not_raise(), id="found item"),
+        pytest.param(DUMMY_DATA, "name", "Jack", "default_value", False, False, None, None, "default_value", does_not_raise(), id="default value"),
+        pytest.param(DUMMY_DATA, "name", "Jack", None, True, False, None, None, None, pytest.raises(ValueError, match="name"), id="required"),
+        pytest.param(DUMMY_DATA, "name", "Bob", None, False, True, None, None, DUMMY_DATA[2], does_not_raise(), id="case sensitive"),
+        pytest.param(DUMMY_DATA, "name", "charlie", None, False, False, None, None, DUMMY_DATA[3], does_not_raise(), id="case insensitive"),
+        pytest.param(
+            DUMMY_DATA, "name", "Jack", None, True, False, "custom_var_name", None, None, pytest.raises(ValueError, match="custom_var_name"), id="custom var_name"
+        ),
+        pytest.param(
+            DUMMY_DATA, "name", "Jack", None, True, False, None, "custom_error_msg", None, pytest.raises(ValueError, match="custom_error_msg"), id="custom error msg"
+        ),
+    ],
+)
+def test_get_item(
+    list_of_dicts: list[dict[Any, Any]],
+    key: Any,
+    value: Any,
+    default: Any | None,
+    required: bool,
+    case_sensitive: bool,
+    var_name: str | None,
+    custom_error_msg: str | None,
+    expected_result: str,
+    expected_raise: Any,
+) -> None:
+    """Test get_item."""
+    # pylint: disable=too-many-arguments
+    with expected_raise:
+        assert get_item(list_of_dicts, key, value, default, required, case_sensitive, var_name, custom_error_msg) == expected_result