Fix injecting special interfaces with no auto_bind

This concerns injecting ProviderOf and AssistedBuilder "interfaces".

CHANGES

@@ -10,6 +10,9 @@ Injector Change Log
   :class:`~injector.Module` constructors or :meth:`injector.Module.configure` methods)
 - removed `extends` decorator
 - few classes got useful __repr__ implementations
+- fixed injecting ProviderOf and AssistedBuilders when :class:`injector.Injector`
+  auto_bind is set to False (previously would result in `UnsatisfiedRequirement`
+  error)
 
 0.9.1
 -----

injector.py

@@ -452,12 +452,20 @@ class Binder(object):
         try:
             return self._get_binding(key)
         except (KeyError, UnsatisfiedRequirement):
-            if self._auto_bind:
+            # The special interface is added here so that requesting a special
+            # interface with auto_bind disabled works
+            if self._auto_bind or self._is_special_interface(key.interface):
                 binding = self.create_binding(key.interface)
                 self._bindings[key] = binding
                 return binding
             raise UnsatisfiedRequirement(cls, key)
 
+    def _is_special_interface(self, interface):
+        # "Special" interfaces are ones that you cannot bind yourself but
+        # you can request them (for example you cannot bind ProviderOf(SomeClass)
+        # to anything but you can inject ProviderOf(SomeClass) just fine
+        return isinstance(interface, (ProviderOf, AssistedBuilder))
+
 
 class Scope(object):
     """A Scope looks up the Provider for a binding.

injector_test.py

@@ -1159,3 +1159,29 @@ def test_providerof_is_safe_to_use_with_multiple_injectors():
 
     assert provider1.get() == 1
     assert provider2.get() == 2
+
+
+def test_special_interfaces_work_with_auto_bind_disabled():
+    class InjectMe(object):
+        pass
+
+    def configure(binder):
+        binder.bind(InjectMe, to=InstanceProvider(InjectMe()))
+
+    injector = Injector(configure, auto_bind=False)
+
+    # This line used to fail with:
+    # Traceback (most recent call last):
+    #   File "/projects/injector/injector_test.py", line 1171,
+    #   in test_auto_bind_disabled_regressions
+    #     injector.get(ProviderOf(InjectMe))
+    #   File "/projects/injector/injector.py", line 687, in get
+    #     binding = self.binder.get_binding(None, key)
+    #   File "/projects/injector/injector.py", line 459, in get_binding
+    #     raise UnsatisfiedRequirement(cls, key)
+    # UnsatisfiedRequirement: unsatisfied requirement on
+    # <injector.ProviderOf object at 0x10ff01550>
+    injector.get(ProviderOf(InjectMe))
+
+    # This used to fail with an error similar to the ProviderOf one
+    injector.get(AssistedBuilder(cls=InjectMe))