Add `Configuration.from_json()` method (#602)

* Add implementation and tests

* Refactor naming in configuration fixtures

* Add typing for .from_json()

* Move get/set_ini_files() methods upper

* Add init implementation and tests

* Refactor typing tests

* Add examples

* Add docs

* Update docs index and readme

* Update changelog

README.rst

@@ -59,7 +59,7 @@ Key features of the ``Dependency Injector``:
 - **Overriding**. Can override any provider by another provider on the fly. This helps in testing
   and configuring dev/stage environment to replace API clients with stubs etc. See
   `Provider overriding <https://python-dependency-injector.ets-labs.org/providers/overriding.html>`_.
-- **Configuration**. Reads configuration from ``yaml`` & ``ini`` files, ``pydantic`` settings,
+- **Configuration**. Reads configuration from ``yaml``, ``ini``, and ``json`` files, ``pydantic`` settings,
   environment variables, and dictionaries.
   See `Configuration provider <https://python-dependency-injector.ets-labs.org/providers/configuration.html>`_.
 - **Resources**. Helps with initialization and configuring of logging, event loop, thread

docs/index.rst

@@ -70,7 +70,7 @@ Key features of the ``Dependency Injector``:
 - **Overriding**. Can override any provider by another provider on the fly. This helps in testing
   and configuring dev/stage environment to replace API clients with stubs etc. See
   :ref:`provider-overriding`.
-- **Configuration**. Reads configuration from ``yaml`` & ``ini`` files, ``pydantic`` settings,
+- **Configuration**. Reads configuration from ``yaml``, ``ini``, and ``json`` files, ``pydantic`` settings,
   environment variables, and dictionaries. See :ref:`configuration-provider`.
 - **Resources**. Helps with initialization and configuring of logging, event loop, thread
   or process pool, etc. Can be used for per-function execution scope in tandem with wiring.

docs/introduction/key_features.rst

@@ -16,7 +16,7 @@ Key features of the ``Dependency Injector``:
 - **Overriding**. Can override any provider by another provider on the fly. This helps in testing
   and configuring dev/stage environment to replace API clients with stubs etc. See
   :ref:`provider-overriding`.
-- **Configuration**. Reads configuration from ``yaml`` & ``ini`` files, ``pydantic`` settings,
+- **Configuration**. Reads configuration from ``yaml``, ``ini``, and ``json`` files, ``pydantic`` settings,
   environment variables, and dictionaries. See :ref:`configuration-provider`.
 - **Resources**. Helps with initialization and configuring of logging, event loop, thread
   or process pool, etc. Can be used for per-function execution scope in tandem with wiring.

docs/main/changelog.rst

@@ -10,6 +10,7 @@ follows `Semantic versioning`_
 
 Development
 -----------
+- Add ``Configuration.from_json()`` method to load configuration from a json file.
 - Improve wording on the "Dependency injection and inversion of control in Python" docs page.
 - Update typing in the main example and cohesion/coupling correlation definition in
   "Dependency injection and inversion of control in Python".

docs/providers/configuration.rst

@@ -136,6 +136,50 @@ To use another loader use ``loader`` argument:
 
    *Don't forget to mirror the changes in the requirements file.*
 
+Loading from a JSON file
+------------------------
+
+``Configuration`` provider can load configuration from a ``json`` file using the
+:py:meth:`Configuration.from_json` method:
+
+.. literalinclude:: ../../examples/providers/configuration/configuration_json.py
+   :language: python
+   :lines: 3-
+   :emphasize-lines: 12
+
+where ``examples/providers/configuration/config.json`` is:
+
+.. literalinclude:: ../../examples/providers/configuration/config.json
+   :language: json
+
+Alternatively, you can provide a path to a json file over the configuration provider argument. In that case,
+the container will call ``config.from_json()`` automatically:
+
+.. code-block:: python
+   :emphasize-lines: 3
+
+   class Container(containers.DeclarativeContainer):
+
+       config = providers.Configuration(json_files=["./config.json"])
+
+
+   if __name__ == "__main__":
+       container = Container()  # Config is loaded from ./config.json
+
+:py:meth:`Configuration.from_json` method supports environment variables interpolation.
+
+.. code-block:: json
+
+   {
+       "section": {
+           "option1": "${ENV_VAR}",
+           "option2": "${ENV_VAR}/path",
+           "option3": "${ENV_VAR:default}"
+       }
+   }
+
+See also: :ref:`configuration-envs-interpolation`.
+
 Loading from a Pydantic settings
 --------------------------------
 

examples/providers/configuration/config.json

@@ -0,0 +1,6 @@
+{
+    "aws": {
+        "access_key_id": "KEY",
+        "secret_access_key": "SECRET"
+    }
+}

examples/providers/configuration/configuration_json.py

@@ -0,0 +1,27 @@
+"""`Configuration` provider values loading example."""
+
+from dependency_injector import containers, providers
+
+
+class Container(containers.DeclarativeContainer):
+
+    config = providers.Configuration()
+
+
+if __name__ == "__main__":
+    container = Container()
+
+    container.config.from_json("./config.json")
+
+    assert container.config() == {
+        "aws": {
+            "access_key_id": "KEY",
+            "secret_access_key": "SECRET",
+        },
+    }
+    assert container.config.aws() == {
+        "access_key_id": "KEY",
+        "secret_access_key": "SECRET",
+    }
+    assert container.config.aws.access_key_id() == "KEY"
+    assert container.config.aws.secret_access_key() == "SECRET"

examples/providers/configuration/configuration_json_init.py

@@ -0,0 +1,25 @@
+"""`Configuration` provider values loading example."""
+
+from dependency_injector import containers, providers
+
+
+class Container(containers.DeclarativeContainer):
+
+    config = providers.Configuration(json_files=["./config.json"])
+
+
+if __name__ == "__main__":
+    container = Container()
+
+    assert container.config() == {
+        "aws": {
+            "access_key_id": "KEY",
+            "secret_access_key": "SECRET",
+        },
+    }
+    assert container.config.aws() == {
+        "access_key_id": "KEY",
+        "secret_access_key": "SECRET",
+    }
+    assert container.config.aws.access_key_id() == "KEY"
+    assert container.config.aws.secret_access_key() == "SECRET"

src/dependency_injector/providers.pxd

@@ -132,8 +132,9 @@ cdef class Configuration(Object):
     cdef str __name
     cdef bint __strict
     cdef dict __children
-    cdef list __yaml_files
     cdef list __ini_files
+    cdef list __yaml_files
+    cdef list __json_files
     cdef list __pydantic_settings
     cdef object __weakref__
 

src/dependency_injector/providers.pyi

@@ -218,6 +218,7 @@ class ConfigurationOption(Provider[Any]):
     def update(self, value: Any) -> None: ...
     def from_ini(self, filepath: Union[Path, str], required: bool = False, envs_required: bool = False) -> None: ...
     def from_yaml(self, filepath: Union[Path, str], required: bool = False, loader: Optional[Any] = None, envs_required: bool = False) -> None: ...
+    def from_json(self, filepath: Union[Path, str], required: bool = False, envs_required: bool = False) -> None: ...
     def from_pydantic(self, settings: PydanticSettings, required: bool = False, **kwargs: Any) -> None: ...
     def from_dict(self, options: _Dict[str, Any], required: bool = False) -> None: ...
     def from_env(self, name: str, default: Optional[Any] = None, required: bool = False, as_: Optional[_Callable[..., Any]] = None) -> None: ...
@@ -237,8 +238,9 @@ class Configuration(Object[Any]):
             default: Optional[Any] = None,
             *,
             strict: bool = False,
-            yaml_files: Optional[_Iterable[Union[Path, str]]] = None,
             ini_files: Optional[_Iterable[Union[Path, str]]] = None,
+            yaml_files: Optional[_Iterable[Union[Path, str]]] = None,
+            json_files: Optional[_Iterable[Union[Path, str]]] = None,
             pydantic_settings: Optional[_Iterable[PydanticSettings]] = None,
     ) -> None: ...
     def __enter__(self) -> Configuration : ...
@@ -258,11 +260,14 @@ class Configuration(Object[Any]):
     def get_children(self) -> _Dict[str, ConfigurationOption]: ...
     def set_children(self, children: _Dict[str, ConfigurationOption]) -> Configuration: ...
 
+    def get_ini_files(self) -> _List[Union[Path, str]]: ...
+    def set_ini_files(self, files: _Iterable[Union[Path, str]]) -> Configuration: ...
+
     def get_yaml_files(self) -> _List[Union[Path, str]]: ...
     def set_yaml_files(self, files: _Iterable[Union[Path, str]]) -> Configuration: ...
 
-    def get_ini_files(self) -> _List[Union[Path, str]]: ...
-    def set_ini_files(self, files: _Iterable[Union[Path, str]]) -> Configuration: ...
+    def get_json_files(self) -> _List[Union[Path, str]]: ...
+    def set_json_files(self, files: _Iterable[Union[Path, str]]) -> Configuration: ...
 
     def get_pydantic_settings(self) -> _List[PydanticSettings]: ...
     def set_pydantic_settings(self, settings: _Iterable[PydanticSettings]) -> Configuration: ...
@@ -275,6 +280,7 @@ class Configuration(Object[Any]):
     def update(self, value: Any) -> None: ...
     def from_ini(self, filepath: Union[Path, str], required: bool = False, envs_required: bool = False) -> None: ...
     def from_yaml(self, filepath: Union[Path, str], required: bool = False, loader: Optional[Any] = None, envs_required: bool = False) -> None: ...
+    def from_json(self, filepath: Union[Path, str], required: bool = False, envs_required: bool = False) -> None: ...
     def from_pydantic(self, settings: PydanticSettings, required: bool = False, **kwargs: Any) -> None: ...
     def from_dict(self, options: _Dict[str, Any], required: bool = False) -> None: ...
     def from_env(self, name: str, default: Optional[Any] = None, required: bool = False, as_: Optional[_Callable[..., Any]] = None) -> None: ...

src/dependency_injector/providers.pyx

@@ -5,13 +5,14 @@ from __future__ import absolute_import
 import copy
 import errno
 import functools
-import inspect
 import importlib
+import inspect
+import json
 import os
 import re
 import sys
-import types
 import threading
+import types
 import warnings
 
 try:
@@ -1741,6 +1742,44 @@ cdef class ConfigurationOption(Provider):
             current_config = {}
         self.override(merge_dicts(current_config, config))
 
+    def from_json(self, filepath, required=UNDEFINED, envs_required=UNDEFINED):
+        """Load configuration from a json file.
+
+        Loaded configuration is merged recursively over the existing configuration.
+
+        :param filepath: Path to a configuration file.
+        :type filepath: str
+
+        :param required: When required is True, raise an exception if file does not exist.
+        :type required: bool
+
+        :param envs_required: When True, raises an exception on undefined environment variable.
+        :type envs_required: bool
+
+        :rtype: None
+        """
+        try:
+            with open(filepath) as opened_file:
+                config_content = opened_file.read()
+        except IOError as exception:
+            if required is not False \
+                    and (self._is_strict_mode_enabled() or required is True) \
+                    and exception.errno in (errno.ENOENT, errno.EISDIR):
+                exception.strerror = "Unable to load configuration file {0}".format(exception.strerror)
+                raise
+            return
+
+        config_content = _resolve_config_env_markers(
+            config_content,
+            envs_required=envs_required if envs_required is not UNDEFINED else self._is_strict_mode_enabled(),
+        )
+        config = json.loads(config_content)
+
+        current_config = self.__call__()
+        if not current_config:
+            current_config = {}
+        self.override(merge_dicts(current_config, config))
+
     def from_pydantic(self, settings, required=UNDEFINED, **kwargs):
         """Load configuration from pydantic settings.
 
@@ -1886,24 +1925,29 @@ cdef class Configuration(Object):
 
     DEFAULT_NAME = "config"
 
-    def __init__(self, name=DEFAULT_NAME, default=None, strict=False, yaml_files=None, ini_files=None, pydantic_settings=None):
+    def __init__(self, name=DEFAULT_NAME, default=None, strict=False, ini_files=None, yaml_files=None, json_files=None, pydantic_settings=None):
         self.__name = name
         self.__strict = strict
         self.__children = {}
-        self.__yaml_files = []
         self.__ini_files = []
+        self.__yaml_files = []
+        self.__json_files = []
         self.__pydantic_settings = []
 
         super().__init__(provides={})
         self.set_default(default)
 
+        if ini_files is None:
+            ini_files = []
+        self.set_ini_files(ini_files)
+
         if yaml_files is None:
             yaml_files = []
         self.set_yaml_files(yaml_files)
 
-        if ini_files is None:
-            ini_files = []
-        self.set_ini_files(ini_files)
+        if json_files is None:
+            json_files = []
+        self.set_json_files(json_files)
 
         if pydantic_settings is None:
             pydantic_settings = []
@@ -1919,8 +1963,9 @@ cdef class Configuration(Object):
         copied.set_default(self.get_default())
         copied.set_strict(self.get_strict())
         copied.set_children(deepcopy(self.get_children(), memo))
-        copied.set_yaml_files(self.get_yaml_files())
         copied.set_ini_files(self.get_ini_files())
+        copied.set_yaml_files(self.get_yaml_files())
+        copied.set_json_files(self.get_json_files())
         copied.set_pydantic_settings(self.get_pydantic_settings())
 
         self._copy_overridings(copied, memo)
@@ -1995,6 +2040,15 @@ cdef class Configuration(Object):
         self.__children = children
         return self
 
+    def get_ini_files(self):
+        """Return list of INI files."""
+        return list(self.__ini_files)
+
+    def set_ini_files(self, files):
+        """Set list of INI files."""
+        self.__ini_files = list(files)
+        return self
+
     def get_yaml_files(self):
         """Return list of YAML files."""
         return list(self.__yaml_files)
@@ -2004,13 +2058,13 @@ cdef class Configuration(Object):
         self.__yaml_files = list(files)
         return self
 
-    def get_ini_files(self):
-        """Return list of INI files."""
-        return list(self.__ini_files)
+    def get_json_files(self):
+        """Return list of JSON files."""
+        return list(self.__json_files)
 
-    def set_ini_files(self, files):
-        """Set list of INI files."""
-        self.__ini_files = list(files)
+    def set_json_files(self, files):
+        """Set list of JSON files."""
+        self.__json_files = list(files)
         return self
 
     def get_pydantic_settings(self):
@@ -2039,11 +2093,14 @@ cdef class Configuration(Object):
         :param envs_required: When True, raises an error on undefined environment variable.
         :type envs_required: bool
         """
+        for file in self.get_ini_files():
+            self.from_ini(file, required=required, envs_required=envs_required)
+
         for file in self.get_yaml_files():
             self.from_yaml(file, required=required, envs_required=envs_required)
 
-        for file in self.get_ini_files():
-            self.from_ini(file, required=required, envs_required=envs_required)
+        for file in self.get_json_files():
+            self.from_json(file, required=required, envs_required=envs_required)
 
         for settings in self.get_pydantic_settings():
             self.from_pydantic(settings, required=required)
@@ -2254,6 +2311,44 @@ cdef class Configuration(Object):
             current_config = {}
         self.override(merge_dicts(current_config, config))
 
+    def from_json(self, filepath, required=UNDEFINED, envs_required=UNDEFINED):
+        """Load configuration from a json file.
+
+        Loaded configuration is merged recursively over the existing configuration.
+
+        :param filepath: Path to a configuration file.
+        :type filepath: str
+
+        :param required: When required is True, raise an exception if file does not exist.
+        :type required: bool
+
+        :param envs_required: When True, raises an exception on undefined environment variable.
+        :type envs_required: bool
+
+        :rtype: None
+        """
+        try:
+            with open(filepath) as opened_file:
+                config_content = opened_file.read()
+        except IOError as exception:
+            if required is not False \
+                    and (self._is_strict_mode_enabled() or required is True) \
+                    and exception.errno in (errno.ENOENT, errno.EISDIR):
+                exception.strerror = "Unable to load configuration file {0}".format(exception.strerror)
+                raise
+            return
+
+        config_content = _resolve_config_env_markers(
+            config_content,
+            envs_required=envs_required if envs_required is not UNDEFINED else self._is_strict_mode_enabled(),
+        )
+        config = json.loads(config_content)
+
+        current_config = self.__call__()
+        if not current_config:
+            current_config = {}
+        self.override(merge_dicts(current_config, config))
+
     def from_pydantic(self, settings, required=UNDEFINED, **kwargs):
         """Load configuration from pydantic settings.
 

tests/typing/configuration.py

@@ -1,5 +1,7 @@
 from pathlib import Path
+
 from dependency_injector import providers
+from pydantic import BaseSettings as PydanticSettings
 
 
 # Test 1: to check the getattr
@@ -8,18 +10,26 @@ provider1 = providers.Factory(dict, a=config1.a)
 
 # Test 2: to check the from_*() method
 config2 = providers.Configuration()
+
 config2.from_dict({})
+config2.from_value({})
+
 config2.from_ini("config.ini")
 config2.from_ini(Path("config.ini"))
 
 config2.from_yaml("config.yml")
 config2.from_yaml(Path("config.yml"))
 
+config2.from_json("config.json")
+config2.from_json(Path("config.json"))
+
 config2.from_env("ENV", "default")
 config2.from_env("ENV", as_=int, default=123)
 config2.from_env("ENV", as_=float, required=True)
 config2.from_env("ENV", as_=lambda env: str(env))
 
+config2.from_pydantic(PydanticSettings())
+
 # Test 3: to check as_*() methods
 config3 = providers.Configuration()
 int3: providers.Callable[int] = config3.option.as_int()
@@ -29,3 +39,39 @@ int3_custom: providers.Callable[int] = config3.option.as_(int)
 # Test 4: to check required() method
 config4 = providers.Configuration()
 option4: providers.ConfigurationOption = config4.option.required()
+
+# Test 5: to check get/set config files' methods and init arguments
+# Test 5: ini
+config5_ini = providers.Configuration(
+    ini_files=["config.ini", Path("config.ini")],
+)
+config5_ini.set_ini_files(["config.ini", Path("config.ini")])
+config5_ini_files: list[str | Path] = config5_ini.get_ini_files()
+
+# Test 5: yaml
+config5_yaml = providers.Configuration(
+    yaml_files=["config.yml", Path("config.yml")],
+)
+config5_yaml.set_yaml_files(["config.yml", Path("config.yml")])
+config5_yaml_files: list[str | Path] = config5_yaml.get_yaml_files()
+
+# Test 5: json
+config5_json = providers.Configuration(
+    json_files=["config.json", Path("config.json")],
+)
+config5_json.set_json_files(["config.json", Path("config.json")])
+config5_json_files: list[str | Path] = config5_json.get_json_files()
+
+# Test 5: pydantic
+config5_pydantic = providers.Configuration(
+    pydantic_settings=[PydanticSettings()],
+)
+config5_pydantic.set_pydantic_settings([PydanticSettings()])
+config5_pydantic_settings: list[PydanticSettings] = config5_pydantic.get_pydantic_settings()
+
+# Test 6: to check init arguments
+config6 = providers.Configuration(
+    name="config",
+    strict=True,
+    default={},
+)

tests/unit/providers/configuration/conftest.py

@@ -1,5 +1,6 @@
 """Fixtures module."""
 
+import json
 import os
 
 from dependency_injector import providers
@@ -51,14 +52,14 @@ def ini_config_file_2(tmp_path):
 
 @fixture
 def ini_config_file_3(tmp_path):
-    ini_config_file_3 = str(tmp_path / "config_3.ini")
-    with open(ini_config_file_3, "w") as file:
+    config_file = str(tmp_path / "config_3.ini")
+    with open(config_file, "w") as file:
         file.write(
             "[section1]\n"
             "value1=${CONFIG_TEST_ENV}\n"
             "value2=${CONFIG_TEST_PATH}/path\n"
         )
-    return ini_config_file_3
+    return config_file
 
 
 @fixture
@@ -91,14 +92,70 @@ def yaml_config_file_2(tmp_path):
 
 @fixture
 def yaml_config_file_3(tmp_path):
-    yaml_config_file_3 = str(tmp_path / "config_3.yml")
-    with open(yaml_config_file_3, "w") as file:
+    config_file = str(tmp_path / "config_3.yml")
+    with open(config_file, "w") as file:
         file.write(
             "section1:\n"
             "  value1: ${CONFIG_TEST_ENV}\n"
             "  value2: ${CONFIG_TEST_PATH}/path\n"
         )
-    return yaml_config_file_3
+    return config_file
+
+
+@fixture
+def json_config_file_1(tmp_path):
+    config_file = str(tmp_path / "config_1.json")
+    with open(config_file, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section1": {
+                        "value1": 1,
+                    },
+                    "section2": {
+                        "value2": 2,
+                    },
+                },
+            ),
+        )
+    return config_file
+
+
+@fixture
+def json_config_file_2(tmp_path):
+    config_file = str(tmp_path / "config_2.json")
+    with open(config_file, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section1": {
+                        "value1": 11,
+                        "value11": 11,
+                    },
+                    "section3": {
+                        "value3": 3,
+                    },
+                },
+            ),
+        )
+    return config_file
+
+
+@fixture
+def json_config_file_3(tmp_path):
+    config_file = str(tmp_path / "config_3.json")
+    with open(config_file, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section1": {
+                        "value1": "${CONFIG_TEST_ENV}",
+                        "value2": "${CONFIG_TEST_PATH}/path",
+                    },
+                },
+            ),
+        )
+    return config_file
 
 
 @fixture(autouse=True)

tests/unit/providers/configuration/test_from_json_py2_py3.py

@@ -0,0 +1,84 @@
+"""Configuration.from_json() tests."""
+
+from dependency_injector import errors
+from pytest import mark, raises
+
+
+def test(config, json_config_file_1):
+    config.from_json(json_config_file_1)
+
+    assert config() == {"section1": {"value1": 1}, "section2": {"value2": 2}}
+    assert config.section1() == {"value1": 1}
+    assert config.section1.value1() == 1
+    assert config.section2() == {"value2": 2}
+    assert config.section2.value2() == 2
+
+
+def test_merge(config, json_config_file_1, json_config_file_2):
+    config.from_json(json_config_file_1)
+    config.from_json(json_config_file_2)
+
+    assert config() == {
+        "section1": {
+            "value1": 11,
+            "value11": 11,
+        },
+        "section2": {
+            "value2": 2,
+        },
+        "section3": {
+            "value3": 3,
+        },
+    }
+    assert config.section1() == {"value1": 11, "value11": 11}
+    assert config.section1.value1() == 11
+    assert config.section1.value11() == 11
+    assert config.section2() == {"value2": 2}
+    assert config.section2.value2() == 2
+    assert config.section3() == {"value3": 3}
+    assert config.section3.value3() == 3
+
+
+def test_file_does_not_exist(config):
+    config.from_json("./does_not_exist.json")
+    assert config() == {}
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_file_does_not_exist_strict_mode(config):
+    with raises(IOError):
+        config.from_json("./does_not_exist.json")
+
+
+def test_option_file_does_not_exist(config):
+    config.option.from_json("./does_not_exist.json")
+    assert config.option() is None
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_option_file_does_not_exist_strict_mode(config):
+    with raises(IOError):
+        config.option.from_json("./does_not_exist.json")
+
+
+def test_required_file_does_not_exist(config):
+    with raises(IOError):
+        config.from_json("./does_not_exist.json", required=True)
+
+
+def test_required_option_file_does_not_exist(config):
+    with raises(IOError):
+        config.option.from_json("./does_not_exist.json", required=True)
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_not_required_file_does_not_exist_strict_mode(config):
+    config.from_json("./does_not_exist.json", required=False)
+    assert config() == {}
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_not_required_option_file_does_not_exist_strict_mode(config):
+    config.option.from_json("./does_not_exist.json", required=False)
+    with raises(errors.Error):
+        config.option()

tests/unit/providers/configuration/test_from_json_with_env_py2_py3.py

@@ -0,0 +1,198 @@
+"""Configuration.from_json() with environment variables interpolation tests."""
+
+import json
+import os
+
+from pytest import mark, raises
+
+
+def test_env_variable_interpolation(config, json_config_file_3):
+    config.from_json(json_config_file_3)
+
+    assert config() == {
+        "section1": {
+            "value1": "test-value",
+            "value2": "test-path/path",
+        },
+    }
+    assert config.section1() == {
+        "value1": "test-value",
+        "value2": "test-path/path",
+    }
+    assert config.section1.value1() == "test-value"
+    assert config.section1.value2() == "test-path/path"
+
+
+def test_missing_envs_not_required(config, json_config_file_3):
+    del os.environ["CONFIG_TEST_ENV"]
+    del os.environ["CONFIG_TEST_PATH"]
+
+    config.from_json(json_config_file_3)
+
+    assert config() == {
+        "section1": {
+            "value1": "",
+            "value2": "/path",
+        },
+    }
+    assert config.section1() == {
+        "value1": "",
+        "value2": "/path",
+    }
+    assert config.section1.value1() == ""
+    assert config.section1.value2() == "/path"
+
+
+def test_missing_envs_required(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    with raises(ValueError, match="Missing required environment variable \"UNDEFINED\""):
+        config.from_json(json_config_file_3, envs_required=True)
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_missing_envs_strict_mode(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    with raises(ValueError, match="Missing required environment variable \"UNDEFINED\""):
+        config.from_json(json_config_file_3)
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_missing_envs_not_required_in_strict_mode(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    config.from_json(json_config_file_3, envs_required=False)
+    assert config.section.undefined() == ""
+
+
+def test_option_missing_envs_not_required(config, json_config_file_3):
+    del os.environ["CONFIG_TEST_ENV"]
+    del os.environ["CONFIG_TEST_PATH"]
+
+    config.option.from_json(json_config_file_3)
+
+    assert config.option() == {
+        "section1": {
+            "value1": "",
+            "value2": "/path",
+        },
+    }
+    assert config.option.section1() == {
+        "value1": "",
+        "value2": "/path",
+    }
+    assert config.option.section1.value1() == ""
+    assert config.option.section1.value2() == "/path"
+
+
+def test_option_missing_envs_required(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    with raises(ValueError, match="Missing required environment variable \"UNDEFINED\""):
+        config.option.from_json(json_config_file_3, envs_required=True)
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_option_missing_envs_not_required_in_strict_mode(config, json_config_file_3):
+    config.override({"option": {}})
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    config.option.from_json(json_config_file_3, envs_required=False)
+    assert config.option.section.undefined() == ""
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_option_missing_envs_strict_mode(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    with raises(ValueError, match="Missing required environment variable \"UNDEFINED\""):
+        config.option.from_json(json_config_file_3)
+
+
+def test_default_values(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "defined_with_default": "${DEFINED:default}",
+                        "undefined_with_default": "${UNDEFINED:default}",
+                        "complex": "${DEFINED}/path/${DEFINED:default}/${UNDEFINED}/${UNDEFINED:default}",
+                    },
+                },
+            ),
+        )
+
+    config.from_json(json_config_file_3)
+
+    assert config.section() == {
+        "defined_with_default": "defined",
+        "undefined_with_default": "default",
+        "complex": "defined/path/defined//default",
+    }
+
+
+def test_option_env_variable_interpolation(config, json_config_file_3):
+    config.option.from_json(json_config_file_3)
+
+    assert config.option() == {
+        "section1": {
+            "value1": "test-value",
+            "value2": "test-path/path",
+        },
+    }
+    assert config.option.section1() == {
+        "value1": "test-value",
+        "value2": "test-path/path",
+    }
+    assert config.option.section1.value1() == "test-value"
+    assert config.option.section1.value2() == "test-path/path"

tests/unit/providers/configuration/test_ini_files_in_init_py2_py3.py

@@ -47,6 +47,11 @@ def test_set_files(config):
     assert config.get_ini_files() == ["file1.ini", "file2.ini"]
 
 
+def test_copy(config, ini_config_file_1, ini_config_file_2):
+    config_copy = providers.deepcopy(config)
+    assert config_copy.get_ini_files() == [ini_config_file_1, ini_config_file_2]
+
+
 def test_file_does_not_exist(config):
     config.set_ini_files(["./does_not_exist.ini"])
     config.load()

tests/unit/providers/configuration/test_json_files_in_init_py2_py3.py

@@ -0,0 +1,114 @@
+"""Configuration(json_files=[...]) tests."""
+
+import json
+
+from dependency_injector import providers
+from pytest import fixture, mark, raises
+
+
+@fixture
+def config(config_type, json_config_file_1, json_config_file_2):
+    if config_type == "strict":
+        return providers.Configuration(strict=True)
+    elif config_type == "default":
+        return providers.Configuration(json_files=[json_config_file_1, json_config_file_2])
+    else:
+        raise ValueError("Undefined config type \"{0}\"".format(config_type))
+
+
+def test_load(config):
+    config.load()
+
+    assert config() == {
+        "section1": {
+            "value1": 11,
+            "value11": 11,
+        },
+        "section2": {
+            "value2": 2,
+        },
+        "section3": {
+            "value3": 3,
+        },
+    }
+    assert config.section1() == {"value1": 11, "value11": 11}
+    assert config.section1.value1() == 11
+    assert config.section1.value11() == 11
+    assert config.section2() == {"value2": 2}
+    assert config.section2.value2() == 2
+    assert config.section3() == {"value3": 3}
+    assert config.section3.value3() == 3
+
+
+def test_get_files(config, json_config_file_1, json_config_file_2):
+    assert config.get_json_files() == [json_config_file_1, json_config_file_2]
+
+
+def test_set_files(config):
+    config.set_json_files(["file1.json", "file2.json"])
+    assert config.get_json_files() == ["file1.json", "file2.json"]
+
+
+def test_copy(config, json_config_file_1, json_config_file_2):
+    config_copy = providers.deepcopy(config)
+    assert config_copy.get_json_files() == [json_config_file_1, json_config_file_2]
+
+
+def test_file_does_not_exist(config):
+    config.set_json_files(["./does_not_exist.json"])
+    config.load()
+    assert config() == {}
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_file_does_not_exist_strict_mode(config):
+    config.set_json_files(["./does_not_exist.json"])
+    with raises(IOError):
+        config.load()
+    assert config() == {}
+
+
+def test_required_file_does_not_exist(config):
+    config.set_json_files(["./does_not_exist.json"])
+    with raises(IOError):
+        config.load(required=True)
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_not_required_file_does_not_exist_strict_mode(config):
+    config.set_json_files(["./does_not_exist.json"])
+    config.load(required=False)
+    assert config() == {}
+
+
+def test_missing_envs_required(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    config.set_json_files([json_config_file_3])
+    with raises(ValueError, match="Missing required environment variable \"UNDEFINED\""):
+        config.load(envs_required=True)
+
+
+@mark.parametrize("config_type", ["strict"])
+def test_missing_envs_not_required_in_strict_mode(config, json_config_file_3):
+    with open(json_config_file_3, "w") as file:
+        file.write(
+            json.dumps(
+                {
+                    "section": {
+                        "undefined": "${UNDEFINED}",
+                    },
+                },
+            ),
+        )
+    config.set_json_files([json_config_file_3])
+    config.load(envs_required=False)
+    assert config.section.undefined() == ""

tests/unit/providers/configuration/test_pydantic_settings_in_init_py36.py

@@ -80,6 +80,11 @@ def test_get_pydantic_settings(config, pydantic_settings_1, pydantic_settings_2)
     assert config.get_pydantic_settings() == [pydantic_settings_1, pydantic_settings_2]
 
 
+def test_copy(config, pydantic_settings_1, pydantic_settings_2):
+    config_copy = providers.deepcopy(config)
+    assert config_copy.get_pydantic_settings() == [pydantic_settings_1, pydantic_settings_2]
+
+
 def test_set_pydantic_settings(config):
     class Settings3(pydantic.BaseSettings):
         ...

tests/unit/providers/configuration/test_yaml_files_in_init_py2_py3.py

@@ -47,6 +47,11 @@ def test_set_files(config):
     assert config.get_yaml_files() == ["file1.yml", "file2.yml"]
 
 
+def test_copy(config, yaml_config_file_1, yaml_config_file_2):
+    config_copy = providers.deepcopy(config)
+    assert config_copy.get_yaml_files() == [yaml_config_file_1, yaml_config_file_2]
+
+
 def test_file_does_not_exist(config):
     config.set_yaml_files(["./does_not_exist.yml"])
     config.load()