#21 Config class

Config class

Author: NickPapONS

.vscode/settings.json

@@ -1,6 +1,7 @@
 {
     "python.testing.pytestArgs": [
-        "tests"
+        "tests",
+        "dpytools"
     ],
     "python.testing.unittestEnabled": false,
     "python.testing.pytestEnabled": true

dpytools/config/config.py

@@ -1,38 +1,82 @@
-from typing import Dict
+from __future__ import annotations
+
+import os
+from typing import Any, Dict, List
 
 from .properties.base import BaseProperty
+from .properties.intproperty import IntegerProperty
+from .properties.string import StringProperty
 
 class Config:
+    
+    def __init__(self):
+        self._properties_to_validate: List[BaseProperty] = []
 
     @staticmethod
-    def from_env(config_dict: Dict[str, BaseProperty]):
-        # TODO = read in and populate property classes as
-        # per the example in the main readme.
-        # You need to populate with dot notation in mind so:
-        #
-        # StringProperty("fieldname", "fieldvalue")
-        #
-        # should be accessed on Config/self, so:
-        #
-        # value = config.fieldvalue.value
-        # i.e
-        # config.fieldvalue = StringProperty("fieldname", "fieldvalue")
-        #
-        # Worth looking at the __setattr_ dunder method and a loop
-        # for how to do this.
-        #
-        # Do track the BaseProperty's that you add ready for
-        # assert_valid_config call.
-        ...
+    def from_env(config_dict: Dict[str, Dict[str, Any]]) -> Config:
+
+        config = Config()
+
+        for env_var_name, value in config_dict.items():
+
+            value_for_property = os.environ.get(env_var_name, None)
+            assert value_for_property is not None, f'Required envionrment value "{env_var_name}" could not be found.'
+
+            if value["class"] == StringProperty:
+                if value["kwargs"]:
+                    regex = value["kwargs"].get("regex")
+                    min_len = value["kwargs"].get("min_len")
+                    max_len = value["kwargs"].get("max_len")
+                else:
+                    regex = None
+                    min_len = None
+                    max_len = None
+  
+                stringprop = StringProperty(
+                    _name = value["property"],
+                    _value = value_for_property,
+                    regex = regex,
+                    min_len = min_len,
+                    max_len = max_len
+                )
+
+                prop_name = value["property"]
+                setattr(config, prop_name, stringprop)
+                config._properties_to_validate.append(stringprop)
+
+            elif value["class"] == IntegerProperty:
+                if value["kwargs"]:
+                    min_val = value["kwargs"].get("min_val")
+                    max_val = value["kwargs"].get("max_val")
+                else:
+                    min_val = None
+                    max_val = None
+
+                intprop = IntegerProperty(
+                    _name = value["property"],
+                    _value = value_for_property,
+                    min_val = min_val,
+                    max_val = max_val
+                )
+
+                prop_name = value["property"]
+                setattr(config, prop_name, intprop)
+                config._properties_to_validate.append(intprop)
+
+            else:
+                prop_type = value["class"]
+                raise TypeError(f"Unsupported property type specified via 'property' field, got {prop_type}. Should be of type StringProperty or IntegerProperty")
+
+        return  config
+
 
     def assert_valid_config(self):
         """
         Assert that then Config class has the properties that
         provided properties.
         """
+        for property in self._properties_to_validate:
+            property.type_is_valid()
+            property.secondary_validation()
 
-        # For each of the properties you imbided above, run
-        # self.type_is_valid()
-        # self.secondary_validation()
-
-        
+        self._properties_to_validate = []

dpytools/config/properties/__init__.py

@@ -1 +1,2 @@
-from .string import StringProperty
+from .string import StringProperty
+from .intproperty import IntegerProperty

dpytools/config/properties/base.py

@@ -4,17 +4,24 @@
 
 @dataclass
 class BaseProperty(metaclass=ABCMeta):
-    name: str
-    value: Any
+    _name: str
+    _value: Any
 
-    # TODO: getter
-    # allow someone to get the property
+    @property
+    def name(self):
+        return self._name
 
-    # TODO: setter
-    # categorically disallow anyone from
-    # changing a property after the class
-    # has been instantiated.
-    # Refuse to do it, and log an error.
+    @name.setter
+    def name(self, value):
+         raise ValueError(f"Trying to change name property to value {value} but you cannot change a property name after instantiation.")
+
+    @property
+    def value(self):
+        return self._value
+
+    @value.setter
+    def value(self, value):
+        raise ValueError(f"Trying to change value to {value} but you cannot change a property value after instantiation.")
 
     @abstractmethod
     def type_is_valid(self):

dpytools/config/properties/intproperty.py

@@ -0,0 +1,32 @@
+from typing import Optional
+from dataclasses import dataclass
+from .base import BaseProperty
+
+@dataclass
+class IntegerProperty(BaseProperty):
+    min_val: Optional[int]
+    max_val: Optional[int]
+
+    def type_is_valid(self):
+        """
+        Validate that the property looks like
+        its of the correct type 
+        """
+        try:
+            int(self._value)
+        except Exception as err:
+            raise Exception(f"Cannot cast {self._name} value {self._value} to integer.") from err
+
+    def secondary_validation(self):
+        """
+        Non type based validation you might want to
+        run against a configuration value of this kind.
+        """
+        if not self._value:
+            raise ValueError(f"Integer value for {self._name} does not exist.")
+
+        if self.min_val and self._value < self.min_val:
+            raise ValueError(f"Integer value for {self._name} is lower than allowed minimum.")
+
+        if self.max_val and self._value > self.max_val:
+            raise ValueError(f"Integer value for {self._name} is higher than allowed maximum.")

dpytools/config/properties/string.py

@@ -1,8 +1,10 @@
 from typing import Optional
-
+from dataclasses import dataclass
 from .base import BaseProperty
 
+import re
 
+@dataclass
 class StringProperty(BaseProperty):
     regex: Optional[str]
     min_len: Optional[int]
@@ -14,26 +16,29 @@ def type_is_valid(self):
         its of the correct type 
         """
         try:
-            str(self.value)
+            str(self._value)
         except Exception as err:
-            raise Exception(f"Cannot cast {self.name} value {self.value} to string.") from err
+            raise Exception(f"Cannot cast {self.name} value {self._value} to string.") from err
 
-    def secondary_validation_passed(self):
+    def secondary_validation(self):
         """
         Non type based validation you might want to
         run against a configuration value of this kind.
         """
-        if len(self.value) == 0:
+        
+        if len(self._value) == 0:
             raise ValueError(f"Str value for {self.name} is an empty string")
 
         if self.regex:
             # TODO - confirm the value matches the regex
-            ...
+            regex_search = re.search(self.regex, self._value)
+            if not regex_search:
+                raise ValueError(f"Str value for {self.name} does not match the given regex.")
 
         if self.min_len:
-            # TODO - confirm the string matches of exceeds the minimum length
-            ...
+            if len(self._value) < self.min_len:
+                raise ValueError(f"Str value for {self.name} is shorter than minimum length {self.min_len}")
 
         if self.max_len:
-            # TODO - confirm the value matches or is less than the max length
-            ...
+            if len(self._value) > self.max_len:
+                raise ValueError(f"Str value for {self.name} is longer than maximum length {self.max_len}")

tests/test_config.py

@@ -0,0 +1,116 @@
+from _pytest.monkeypatch import monkeypatch
+import pytest
+
+from dpytools.config.config import Config
+from dpytools.config.properties.string import StringProperty
+from dpytools.config.properties.intproperty import IntegerProperty
+
+def test_config_loader(monkeypatch):
+    """
+    Tests that a config object can be created and its attributes 
+    dynamically generated from an input config dictionary with the 
+    expected contents.
+    """
+
+    # Assigning environment variable values for config dictionary values
+    monkeypatch.setenv("SOME_STRING_ENV_VAR", "Some string value")
+    monkeypatch.setenv("SOME_URL_ENV_VAR", "https://test.com/some-url")
+    monkeypatch.setenv("SOME_INT_ENV_VAR", "6")
+
+    config_dictionary = {
+    "SOME_STRING_ENV_VAR": {
+        "class": StringProperty,
+        "property": "name1",
+        "kwargs": {
+            "regex": "string value",
+            "min_len": 10
+        },
+    },
+    "SOME_URL_ENV_VAR": {
+        "class": StringProperty,
+        "property": "name2",
+        "kwargs": {
+            "regex": "https://.*",
+            "max_len": 100
+        },
+    },
+    "SOME_INT_ENV_VAR": {
+        "class": IntegerProperty,
+        "property": "name3",
+        "kwargs": {
+            "min_val": 5,
+            "max_val": 27
+        }
+    },
+}
+
+    config = Config.from_env(config_dictionary)
+    
+    # Assertions
+
+    assert config.name1.name == "name1"
+    assert config.name1.value == "Some string value"
+    assert config.name1.min_len == 10
+    assert config.name1.regex == "string value"
+
+    assert config.name2.name == "name2"
+    assert config.name2.value == "https://test.com/some-url"
+    assert config.name2.regex == "https://.*"
+    assert config.name2.max_len == 100
+
+    assert config.name3.name == "name3"
+    assert config.name3.min_val == 5
+    assert config.name3.max_val == 27
+
+
+def test_config_loader_no_values_error():
+    """
+    Tests that an exception will be raised when a config object 
+    is created using the from_env() method but the environment 
+    variable values have not been assigned (values are None).
+    """
+
+    # No environment variable values assigned in this test
+
+    config_dictionary = {
+    "SOME_STRING_ENV_VAR": {
+        "class": StringProperty,
+        "property": "name1",
+        "kwargs": {
+            "min_len": 10
+        },
+    }
+}
+
+    with pytest.raises(Exception) as e:
+
+        config = Config.from_env(config_dictionary)
+
+        assert 'Required environment value "SOME_STRING_ENV_VAR" could not be found.' in str(e.value)
+
+
+def test_config_loader_incorrect_type_error(monkeypatch):
+    """
+    Tests that a TypeError will be raised when a config object 
+    is created using the from_env() method but the type of an
+    attribute being created is not either a StringProperty or IntegerProperty.
+    """
+
+    monkeypatch.setenv("SOME_STRING_ENV_VAR", "Some string value")
+
+    config_dictionary = {
+    "SOME_STRING_ENV_VAR": {
+        "class": int,
+        "property": "name1",
+        "kwargs": {
+            "min_val": 10,
+
+        },
+    }
+}
+
+    with pytest.raises(TypeError) as e:
+
+        config = Config.from_env(config_dictionary)
+
+        assert "Unsupported property type specified via 'property' field, got <class 'int'>. Should be of type StringProperty or IntegerProperty" in str(e.value)