Merge remote-tracking branch 'origin/factory_and_singleton_positional_args'

dependency_injector/__init__.py

@@ -18,6 +18,7 @@ from .providers import Callable
 from .providers import Config
 
 from .injections import Injection
+from .injections import Arg
 from .injections import KwArg
 from .injections import Attribute
 from .injections import Method
@@ -27,6 +28,7 @@ from .utils import is_provider
 from .utils import ensure_is_provider
 from .utils import is_injection
 from .utils import ensure_is_injection
+from .utils import is_arg_injection
 from .utils import is_kwarg_injection
 from .utils import is_attribute_injection
 from .utils import is_method_injection
@@ -59,6 +61,7 @@ __all__ = (
 
     # Injections
     'Injection',
+    'Arg',
     'KwArg',
     'Attribute',
     'Method',
@@ -69,6 +72,7 @@ __all__ = (
     'ensure_is_provider',
     'is_injection',
     'ensure_is_injection',
+    'is_arg_injection',
     'is_kwarg_injection',
     'is_attribute_injection',
     'is_method_injection',

dependency_injector/injections.py

@@ -21,11 +21,10 @@ class Injection(object):
     """Base injection class."""
 
     __IS_INJECTION__ = True
-    __slots__ = ('name', 'injectable', 'is_provider')
+    __slots__ = ('injectable', 'is_provider')
 
-    def __init__(self, name, injectable):
+    def __init__(self, injectable):
         """Initializer."""
-        self.name = name
         self.injectable = injectable
         self.is_provider = is_provider(injectable)
 
@@ -37,19 +36,36 @@ class Injection(object):
         return self.injectable
 
 
-class KwArg(Injection):
+class NamedInjection(Injection):
+    """Base class of named injections."""
+
+    __slots__ = ('name',)
+
+    def __init__(self, name, injectable):
+        """Initializer."""
+        self.name = name
+        super(NamedInjection, self).__init__(injectable)
+
+
+class Arg(Injection):
+    """Positional argument injection."""
+
+    __IS_ARG_INJECTION__ = True
+
+
+class KwArg(NamedInjection):
     """Keyword argument injection."""
 
     __IS_KWARG_INJECTION__ = True
 
 
-class Attribute(Injection):
+class Attribute(NamedInjection):
     """Attribute injection."""
 
     __IS_ATTRIBUTE_INJECTION__ = True
 
 
-class Method(Injection):
+class Method(NamedInjection):
     """Method injection."""
 
     __IS_METHOD_INJECTION__ = True

dependency_injector/providers.py

@@ -2,12 +2,16 @@
 
 import six
 
+from .injections import Arg
 from .injections import KwArg
 
 from .utils import ensure_is_provider
+from .utils import is_injection
+from .utils import is_arg_injection
 from .utils import is_kwarg_injection
 from .utils import is_attribute_injection
 from .utils import is_method_injection
+from .utils import get_injectable_args
 from .utils import get_injectable_kwargs
 from .utils import GLOBAL_LOCK
 
@@ -104,33 +108,35 @@ class Factory(Provider):
     Factory provider creates new instance of specified class on every call.
     """
 
-    __slots__ = ('provides', 'kwargs', 'attributes', 'methods')
+    __slots__ = ('provides', 'args', 'kwargs', 'attributes', 'methods')
 
-    def __init__(self, provides, *injections, **kwargs):
+    def __init__(self, provides, *args, **kwargs):
         """Initializer."""
         if not callable(provides):
             raise Error('Factory provider expects to get callable, ' +
                         'got {0} instead'.format(str(provides)))
         self.provides = provides
+        self.args = tuple(Arg(arg) if not is_injection(arg) else arg
+                          for arg in args
+                          if not is_injection(arg) or is_arg_injection(arg))
         self.kwargs = tuple(injection
-                            for injection in injections
+                            for injection in args
                             if is_kwarg_injection(injection))
         if kwargs:
             self.kwargs += tuple(KwArg(name, value)
                                  for name, value in six.iteritems(kwargs))
         self.attributes = tuple(injection
-                                for injection in injections
+                                for injection in args
                                 if is_attribute_injection(injection))
         self.methods = tuple(injection
-                             for injection in injections
+                             for injection in args
                              if is_method_injection(injection))
         super(Factory, self).__init__()
 
     def _provide(self, *args, **kwargs):
         """Return provided instance."""
-        instance = self.provides(*args,
+        instance = self.provides(*get_injectable_args(args, self.args),
-                                 **get_injectable_kwargs(kwargs,
+                                 **get_injectable_kwargs(kwargs, self.kwargs))
-                                                         self.kwargs))
         for attribute in self.attributes:
             setattr(instance, attribute.name, attribute.value)
         for method in self.methods:
@@ -141,7 +147,7 @@ class Factory(Provider):
     @property
     def injections(self):
         """Return tuple of all injections."""
-        return self.kwargs + self.attributes + self.methods
+        return self.args + self.kwargs + self.attributes + self.methods
 
 
 class Singleton(Provider):
@@ -152,10 +158,10 @@ class Singleton(Provider):
 
     __slots__ = ('instance', 'factory')
 
-    def __init__(self, provides, *injections, **kwargs):
+    def __init__(self, provides, *args, **kwargs):
         """Initializer."""
         self.instance = None
-        self.factory = Factory(provides, *injections, **kwargs)
+        self.factory = Factory(provides, *args, **kwargs)
         super(Singleton, self).__init__()
 
     def _provide(self, *args, **kwargs):
@@ -169,6 +175,11 @@ class Singleton(Provider):
         """Reset instance."""
         self.instance = None
 
+    @property
+    def injections(self):
+        """Return tuple of all injections."""
+        return self.factory.injections
+
 
 class ExternalDependency(Provider):
     """External dependency provider.

dependency_injector/utils.py

@@ -1,6 +1,7 @@
 """Utils module."""
 
 import threading
+import itertools
 
 import six
 
@@ -41,6 +42,12 @@ def ensure_is_injection(instance):
     return instance
 
 
+def is_arg_injection(instance):
+    """Check if instance is positional argument injection instance."""
+    return (not isinstance(instance, six.class_types) and
+            getattr(instance, '__IS_ARG_INJECTION__', False) is True)
+
+
 def is_kwarg_injection(instance):
     """Check if instance is keyword argument injection instance."""
     return (not isinstance(instance, six.class_types) and
@@ -82,9 +89,14 @@ def ensure_is_catalog_bundle(instance):
     return instance
 
 
-def get_injectable_kwargs(kwargs, injections):
+def get_injectable_args(context_args, arg_injections):
-    """Return dictionary of kwargs, patched with injections."""
+    """Return tuple of positional args, patched with injections."""
-    init_kwargs = dict(((injection.name, injection.value)
+    return itertools.chain((arg.value for arg in arg_injections), context_args)
-                        for injection in injections))
+
-    init_kwargs.update(kwargs)
+
-    return init_kwargs
+def get_injectable_kwargs(context_kwargs, kwarg_injections):
+    """Return dictionary of keyword args, patched with injections."""
+    kwargs = dict((kwarg.name, kwarg.value)
+                  for kwarg in kwarg_injections)
+    kwargs.update(context_kwargs)
+    return kwargs

docs/main/changelog.rst

@@ -11,15 +11,17 @@ follows `Semantic versioning`_
 Development version
 -------------------
 
-- Add functionality for decorating classes with ``@di.inject``.
 - Add functionality for creating ``di.AbstractCatalog`` provider bundles.
-- Add enhancement for ``di.AbstractCatalog`` inheritance.
+- Enhance ``di.AbstractCatalog`` inheritance.
 - Add images for catalog "Writing catalogs" and "Operating with catalogs" 
   examples.
-- Add support of Python 3.5.
+- Add functionality for using positional argument injections with 
-- Add support of six 1.10.0.
+  ``di.Factory`` and ``di.Singleton`` providers.
 - Add optimization for ``di.Injection.value`` property that will compute 
   type of injection once, instead of doing this on every call.
+- Add functionality for decorating classes with ``@di.inject``.
+- Add support of Python 3.5.
+- Add support of six 1.10.0.
 - Add minor refactorings and code style fixes.
 
 0.9.5

docs/providers/factory.rst

@@ -15,46 +15,57 @@ Nothing could be better than brief example:
 Factory providers and __init__ injections
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-``di.Factory`` takes a various number of keyword arguments that are 
+``di.Factory`` takes a various number of positional and keyword arguments that 
-transformed into keyword argument injections. Every time, when ``di.Factory`` 
+are used as ``__init__()`` injections. Every time, when ``di.Factory`` 
-creates new one instance, keyword argument injections would be passed as an
+creates new one instance, positional and keyword argument injections would be 
-instance's keyword arguments. 
+passed as an instance's arguments.
 
-All injectable values are provided *"as is"*, except of providers (subclasses 
+Such behaviour is very similar to the standard Python ``functools.partial`` 
-of ``di.Provider``). Providers will be called every time, when injection needs 
+object, except of one thing: all injectable values are provided 
-to be done. For example, if injectable value of keyword argument injection is a
+*"as is"*, except of providers (subclasses of ``di.Provider``). Providers 
-``di.Factory``, it will provide new one instance (as a result of its call) as 
+will be called every time, when injection needs to be done. For example, 
-an injectable value every time, when injection needs to be done.
+if injectable value of injection is a ``di.Factory``, it will provide new one 
+instance (as a result of its call) every time, when injection needs to be done.
 
 Example below is a little bit more complicated. It shows how to create 
-``di.Factory`` of particular class with ``__init__`` keyword argument 
+``di.Factory`` of particular class with ``__init__()`` argument injections 
-injections which injectable values are also provided by another factories:
+which injectable values are also provided by another factories:
 
 .. note:: 
 
-    Current keyword argument injections syntax (in an example below) is a 
+    Current positional and keyword argument injections syntax (in the examples
-    **simplified one**. Full syntax and other types of injections could be 
+    below) is a **simplified one** version of full syntax. Examples of full 
-    found in sections below.
+    syntax and other types of injections could be found in sections below.
 
-    While keyword argument injections may be the best way of passing 
+    While positional / keyword argument injections may be the best way of 
-    injections, current simplified syntax might be the preferable one and 
+    passing injections, current simplified syntax might be the preferable one 
-    could be widely used.
+    and could be widely used.
 
 .. image:: /images/providers/factory_init_injections.png
     :width: 90%
     :align: center
 
-.. literalinclude:: ../../examples/providers/factory_init_injections.py
+Example of usage positional argument injections:
+
+.. literalinclude:: ../../examples/providers/factory_init_args.py
+   :language: python
+
+Example of usage keyword argument injections:
+
+.. literalinclude:: ../../examples/providers/factory_init_kwargs.py
    :language: python
 
 Factory providers and __init__ injections priority
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Next example shows how ``di.Factory`` provider deals with positional and 
-keyword ``__init__`` context arguments. In few words, ``di.Factory`` 
+keyword ``__init__()`` context arguments. In few words, ``di.Factory`` 
-provider fully passes positional context arguments to class's ``__init__`` 
+behaviour here is very like a standard Python ``functools.partial``:
-method, but keyword context arguments have priority on predefined keyword 
+
-argument injections.
+- Positional context arguments will be appended after ``di.Factory`` 
+  positional injections.
+- Keyword context arguments have priority on ``di.Factory`` keyword injections 
+  and will be merged over them.
 
 So, please, follow the example below:
 
@@ -78,8 +89,11 @@ All of those instructions are defined in ``di.injections`` module and are
 subclasses of ``di.injections.Injection`` (shortcut ``di.Injection``). There 
 are several types of injections that are used by ``di.Factory`` provider:
 
++ ``di.Arg`` - injection is done by passing injectable value in object's
+  ``__init__()`` method in time of object's creation as positional argument.
+  Takes injectable value only.
 + ``di.KwArg`` - injection is done by passing injectable value in object's
-  ``__init__()`` method in time of object's creation via keyword argument.
+  ``__init__()`` method in time of object's creation as keyword argument.
   Takes keyword name of ``__init__()`` argument and injectable value.
 + ``di.Attribute`` - injection is done by setting specified attribute with
   injectable value right after object's creation. Takes attribute's name

examples/providers/factory_init_args.py

@@ -0,0 +1,34 @@
+"""`di.Factory` providers with init positional injections example."""
+
+import dependency_injector as di
+
+
+class User(object):
+    """Example class User."""
+
+    def __init__(self, main_photo):
+        """Initializer."""
+        self.main_photo = main_photo
+        super(User, self).__init__()
+
+
+class Photo(object):
+    """Example class Photo."""
+
+# User and Photo factories:
+photos_factory = di.Factory(Photo)
+users_factory = di.Factory(User, photos_factory)
+
+# Creating several User objects:
+user1 = users_factory()  # Same as: user1 = User(Photo())
+user2 = users_factory()  # Same as: user2 = User(Photo())
+
+# Making some asserts:
+assert isinstance(user1, User)
+assert isinstance(user1.main_photo, Photo)
+
+assert isinstance(user2, User)
+assert isinstance(user2.main_photo, Photo)
+
+assert user1 is not user2
+assert user1.main_photo is not user2.main_photo

examples/providers/factory_init_injections_and_contexts.py

@@ -62,7 +62,8 @@ assert user1.credit_card is not user2.credit_card
 main_photo_mock = Photo()
 credit_card_mock = CreditCard()
 
-user3 = users_factory(3, main_photo=main_photo_mock,
+user3 = users_factory(3,
+                      main_photo=main_photo_mock,
                       credit_card=credit_card_mock)
 
 assert user3.id == 3

examples/providers/factory_init_kwargs.py

@@ -1,4 +1,4 @@
-"""`di.Factory` providers with init injections example."""
+"""`di.Factory` providers with init keyword injections example."""
 
 import dependency_injector as di
 
@@ -17,8 +17,7 @@ class Photo(object):
 
 # User and Photo factories:
 photos_factory = di.Factory(Photo)
-users_factory = di.Factory(User,
+users_factory = di.Factory(User, main_photo=photos_factory)
-                           main_photo=photos_factory)
 
 # Creating several User objects:
 user1 = users_factory()  # Same as: user1 = User(main_photo=Photo())

tests/test_injections.py

@@ -9,18 +9,17 @@ class InjectionTests(unittest.TestCase):
 
     def test_init(self):
         """Test Injection creation and initialization."""
-        injection = di.Injection('some_arg_name', 'some_value')
+        injection = di.Injection('some_value')
-        self.assertEqual(injection.name, 'some_arg_name')
         self.assertEqual(injection.injectable, 'some_value')
 
     def test_value_with_scalar_injectable(self):
         """Test Injection value property with scalar value."""
-        injection = di.Injection('some_arg_name', 'some_value')
+        injection = di.Injection('some_value')
         self.assertEqual(injection.value, 'some_value')
 
     def test_value_with_provider_injectable(self):
         """Test Injection value property with provider."""
-        injection = di.Injection('some_arg_name', di.Factory(object))
+        injection = di.Injection(di.Factory(object))
         self.assertIsInstance(injection.value, object)
 
     def test_value_with_catalog_bundle_injectable(self):
@@ -29,12 +28,20 @@ class InjectionTests(unittest.TestCase):
             """Test catalog."""
 
             provider = di.Provider()
-        injection = di.Injection('some_arg_name',
+        injection = di.Injection(TestCatalog.Bundle(TestCatalog.provider))
-                                 TestCatalog.Bundle(TestCatalog.provider))
 
         self.assertIsInstance(injection.value, TestCatalog.Bundle)
 
 
+class ArgTests(unittest.TestCase):
+    """Positional arg injection test cases."""
+
+    def test_init(self):
+        """Test Arg creation and initialization."""
+        injection = di.Arg('some_value')
+        self.assertEqual(injection.injectable, 'some_value')
+
+
 class KwArgTests(unittest.TestCase):
     """Keyword arg injection test cases."""
 

tests/test_providers.py

@@ -4,6 +4,34 @@ import unittest2 as unittest
 import dependency_injector as di
 
 
+class Example(object):
+    """Example class for Factory provider tests."""
+
+    def __init__(self, init_arg1=None, init_arg2=None):
+        """Initializer.
+
+        :param init_arg1:
+        :param init_arg2:
+        :return:
+        """
+        self.init_arg1 = init_arg1
+        self.init_arg2 = init_arg2
+
+        self.attribute1 = None
+        self.attribute2 = None
+
+        self.method1_value = None
+        self.method2_value = None
+
+    def method1(self, value):
+        """Setter method 1."""
+        self.method1_value = value
+
+    def method2(self, value):
+        """Setter method 2."""
+        self.method2_value = value
+
+
 class ProviderTests(unittest.TestCase):
     """Provider test cases."""
 
@@ -132,36 +160,9 @@ class DelegateTests(unittest.TestCase):
 class FactoryTests(unittest.TestCase):
     """Factory test cases."""
 
-    class Example(object):
-        """Example class for Factory provider tests."""
-
-        def __init__(self, init_arg1=None, init_arg2=None):
-            """Initializer.
-
-            :param init_arg1:
-            :param init_arg2:
-            :return:
-            """
-            self.init_arg1 = init_arg1
-            self.init_arg2 = init_arg2
-
-            self.attribute1 = None
-            self.attribute2 = None
-
-            self.method1_value = None
-            self.method2_value = None
-
-        def method1(self, value):
-            """Setter method 1."""
-            self.method1_value = value
-
-        def method2(self, value):
-            """Setter method 2."""
-            self.method2_value = value
-
     def test_is_provider(self):
         """Test `is_provider` check."""
-        self.assertTrue(di.is_provider(di.Factory(self.Example)))
+        self.assertTrue(di.is_provider(di.Factory(Example)))
 
     def test_init_with_callable(self):
         """Test creation of provider with a callable."""
@@ -173,22 +174,20 @@ class FactoryTests(unittest.TestCase):
 
     def test_call(self):
         """Test creation of new instances."""
-        provider = di.Factory(self.Example)
+        provider = di.Factory(Example)
         instance1 = provider()
         instance2 = provider()
 
         self.assertIsNot(instance1, instance2)
-        self.assertIsInstance(instance1, self.Example)
+        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, self.Example)
+        self.assertIsInstance(instance2, Example)
 
-    def test_call_with_init_args_simplified_syntax(self):
+    def test_call_with_init_positional_args(self):
-        """Test creation of new instances with init args injections.
+        """Test creation of new instances with init positional args.
 
         New simplified syntax.
         """
-        provider = di.Factory(self.Example,
+        provider = di.Factory(Example, 'i1', 'i2')
-                              init_arg1='i1',
-                              init_arg2='i2')
 
         instance1 = provider()
         instance2 = provider()
@@ -200,13 +199,56 @@ class FactoryTests(unittest.TestCase):
         self.assertEqual(instance2.init_arg2, 'i2')
 
         self.assertIsNot(instance1, instance2)
-        self.assertIsInstance(instance1, self.Example)
+        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, self.Example)
+        self.assertIsInstance(instance2, Example)
 
-    def test_call_with_init_args_old_syntax(self):
+    def test_call_with_init_keyword_args(self):
-        """Test creation of new instances with init args injections."""
+        """Test creation of new instances with init keyword args.
-        provider = di.Factory(self.Example,
+
-                              di.KwArg('init_arg1', 'i1'),
+        New simplified syntax.
+        """
+        provider = di.Factory(Example, init_arg1='i1', init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIsNot(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_and_keyword_args(self):
+        """Test creation of new instances with init positional and keyword args.
+
+        Simplified syntax of positional and keyword arg injections.
+        """
+        provider = di.Factory(Example, 'i1', init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIsNot(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_and_keyword_args_extended_syntax(self):
+        """Test creation of new instances with init positional and keyword args.
+
+        Extended syntax of positional and keyword arg injections.
+        """
+        provider = di.Factory(Example,
+                              di.Arg('i1'),
                               di.KwArg('init_arg2', 'i2'))
 
         instance1 = provider()
@@ -219,12 +261,12 @@ class FactoryTests(unittest.TestCase):
         self.assertEqual(instance2.init_arg2, 'i2')
 
         self.assertIsNot(instance1, instance2)
-        self.assertIsInstance(instance1, self.Example)
+        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, self.Example)
+        self.assertIsInstance(instance2, Example)
 
     def test_call_with_attributes(self):
         """Test creation of new instances with attribute injections."""
-        provider = di.Factory(self.Example,
+        provider = di.Factory(Example,
                               di.Attribute('attribute1', 'a1'),
                               di.Attribute('attribute2', 'a2'))
 
@@ -238,12 +280,12 @@ class FactoryTests(unittest.TestCase):
         self.assertEqual(instance2.attribute2, 'a2')
 
         self.assertIsNot(instance1, instance2)
-        self.assertIsInstance(instance1, self.Example)
+        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, self.Example)
+        self.assertIsInstance(instance2, Example)
 
     def test_call_with_methods(self):
         """Test creation of new instances with method injections."""
-        provider = di.Factory(self.Example,
+        provider = di.Factory(Example,
                               di.Method('method1', 'm1'),
                               di.Method('method2', 'm2'))
 
@@ -257,12 +299,12 @@ class FactoryTests(unittest.TestCase):
         self.assertEqual(instance2.method2_value, 'm2')
 
         self.assertIsNot(instance1, instance2)
-        self.assertIsInstance(instance1, self.Example)
+        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, self.Example)
+        self.assertIsInstance(instance2, Example)
 
     def test_call_with_context_args(self):
         """Test creation of new instances with context args."""
-        provider = di.Factory(self.Example)
+        provider = di.Factory(Example)
         instance = provider(11, 22)
 
         self.assertEqual(instance.init_arg1, 11)
@@ -270,7 +312,7 @@ class FactoryTests(unittest.TestCase):
 
     def test_call_with_context_kwargs(self):
         """Test creation of new instances with context kwargs."""
-        provider = di.Factory(self.Example,
+        provider = di.Factory(Example,
                               di.KwArg('init_arg1', 1))
 
         instance1 = provider(init_arg2=22)
@@ -283,7 +325,7 @@ class FactoryTests(unittest.TestCase):
 
     def test_call_overridden(self):
         """Test creation of new instances on overridden provider."""
-        provider = di.Factory(self.Example)
+        provider = di.Factory(Example)
         overriding_provider1 = di.Factory(dict)
         overriding_provider2 = di.Factory(list)
 
@@ -298,9 +340,9 @@ class FactoryTests(unittest.TestCase):
         self.assertIsInstance(instance2, list)
 
     def test_injections(self):
-        """Test getting a full list of injections using Factory.injections."""
+        """Test getting a full list of injections using injections property."""
-        provider = di.Factory(self.Example,
+        provider = di.Factory(Example,
-                              di.KwArg('init_arg1', 1),
+                              di.Arg(1),
                               di.KwArg('init_arg2', 2),
                               di.Attribute('attribute1', 3),
                               di.Attribute('attribute2', 4),
@@ -315,16 +357,199 @@ class FactoryTests(unittest.TestCase):
 class SingletonTests(unittest.TestCase):
     """Singleton test cases."""
 
+    def test_is_provider(self):
+        """Test `is_provider` check."""
+        self.assertTrue(di.is_provider(di.Singleton(Example)))
+
+    def test_init_with_callable(self):
+        """Test creation of provider with a callable."""
+        self.assertTrue(di.Singleton(credits))
+
+    def test_init_with_not_callable(self):
+        """Test creation of provider with not a callable."""
+        self.assertRaises(di.Error, di.Singleton, 123)
+
     def test_call(self):
-        """Test creation and returning of single object."""
+        """Test getting of instances."""
-        provider = di.Singleton(object)
+        provider = di.Singleton(Example)
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_args(self):
+        """Test getting of instances with init positional args.
+
+        New simplified syntax.
+        """
+        provider = di.Singleton(Example, 'i1', 'i2')
 
         instance1 = provider()
         instance2 = provider()
 
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_keyword_args(self):
+        """Test getting of instances with init keyword args.
+
+        New simplified syntax.
+        """
+        provider = di.Singleton(Example, init_arg1='i1', init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_and_keyword_args(self):
+        """Test getting of instances with init positional and keyword args.
+
+        Simplified syntax of positional and keyword arg injections.
+        """
+        provider = di.Singleton(Example, 'i1', init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_and_keyword_args_extended_syntax(self):
+        """Test getting of instances with init positional and keyword args.
+
+        Extended syntax of positional and keyword arg injections.
+        """
+        provider = di.Singleton(Example,
+                                di.Arg('i1'),
+                                di.KwArg('init_arg2', 'i2'))
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_attributes(self):
+        """Test getting of instances with attribute injections."""
+        provider = di.Singleton(Example,
+                                di.Attribute('attribute1', 'a1'),
+                                di.Attribute('attribute2', 'a2'))
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.attribute1, 'a1')
+        self.assertEqual(instance1.attribute2, 'a2')
+
+        self.assertEqual(instance2.attribute1, 'a1')
+        self.assertEqual(instance2.attribute2, 'a2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_methods(self):
+        """Test getting of instances with method injections."""
+        provider = di.Singleton(Example,
+                                di.Method('method1', 'm1'),
+                                di.Method('method2', 'm2'))
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.method1_value, 'm1')
+        self.assertEqual(instance1.method2_value, 'm2')
+
+        self.assertEqual(instance2.method1_value, 'm1')
+        self.assertEqual(instance2.method2_value, 'm2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_context_args(self):
+        """Test getting of instances with context args."""
+        provider = di.Singleton(Example)
+        instance = provider(11, 22)
+
+        self.assertEqual(instance.init_arg1, 11)
+        self.assertEqual(instance.init_arg2, 22)
+
+    def test_call_with_context_kwargs(self):
+        """Test getting of instances with context kwargs."""
+        provider = di.Singleton(Example,
+                                di.KwArg('init_arg1', 1))
+
+        instance1 = provider(init_arg2=22)
+        self.assertEqual(instance1.init_arg1, 1)
+        self.assertEqual(instance1.init_arg2, 22)
+
+        # Instance is created earlier
+        instance1 = provider(init_arg1=11, init_arg2=22)
+        self.assertEqual(instance1.init_arg1, 1)
+        self.assertEqual(instance1.init_arg2, 22)
+
+    def test_call_overridden(self):
+        """Test getting of instances on overridden provider."""
+        provider = di.Singleton(Example)
+        overriding_provider1 = di.Singleton(dict)
+        overriding_provider2 = di.Singleton(object)
+
+        provider.override(overriding_provider1)
+        provider.override(overriding_provider2)
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertIs(instance1, instance2)
         self.assertIsInstance(instance1, object)
         self.assertIsInstance(instance2, object)
-        self.assertIs(instance1, instance2)
+
+    def test_injections(self):
+        """Test getting a full list of injections using injections property."""
+        provider = di.Singleton(Example,
+                                di.Arg(1),
+                                di.KwArg('init_arg2', 2),
+                                di.Attribute('attribute1', 3),
+                                di.Attribute('attribute2', 4),
+                                di.Method('method1', 5),
+                                di.Method('method2', 6))
+
+        injections = provider.injections
+
+        self.assertEquals(len(injections), 6)
 
     def test_reset(self):
         """Test creation and reset of single object."""

tests/test_utils.py

@@ -68,10 +68,11 @@ class IsInjectionTests(unittest.TestCase):
 
     def test_with_instance(self):
         """Test with instance."""
-        self.assertTrue(di.is_injection(di.Injection('name', 'value')))
+        self.assertTrue(di.is_injection(di.Injection('value')))
 
     def test_with_subclass_instances(self):
         """Test with subclass instances."""
+        self.assertTrue(di.is_injection(di.Arg('value')))
         self.assertTrue(di.is_injection(di.KwArg('name', 'value')))
         self.assertTrue(di.is_injection(di.Attribute('name', 'value')))
         self.assertTrue(di.is_injection(di.Method('name', 'value')))
@@ -94,7 +95,7 @@ class EnsureIsInjectionTests(unittest.TestCase):
 
     def test_with_instance(self):
         """Test with instance."""
-        injection = di.Injection('name', 'value')
+        injection = di.Injection('value')
         self.assertIs(di.ensure_is_injection(injection), injection)
 
     def test_with_class(self):
@@ -110,6 +111,30 @@ class EnsureIsInjectionTests(unittest.TestCase):
         self.assertRaises(di.Error, di.ensure_is_injection, object())
 
 
+class IsArgInjectionTests(unittest.TestCase):
+    """`is_arg_injection()` test cases."""
+
+    def test_with_instance(self):
+        """Test with instance."""
+        self.assertTrue(di.is_arg_injection(di.Arg('value')))
+
+    def test_with_class(self):
+        """Test with class."""
+        self.assertFalse(di.is_arg_injection(di.Arg))
+
+    def test_with_parent_class(self):
+        """Test with parent class."""
+        self.assertFalse(di.is_arg_injection(di.Injection))
+
+    def test_with_string(self):
+        """Test with string."""
+        self.assertFalse(di.is_arg_injection('some_string'))
+
+    def test_with_object(self):
+        """Test with object."""
+        self.assertFalse(di.is_arg_injection(object()))
+
+
 class IsKwArgInjectionTests(unittest.TestCase):
     """`is_kwarg_injection()` test cases."""