Add typing tests

tests/typing/aggregate.py

@@ -0,0 +1,32 @@
+from dependency_injector import providers
+
+
+class Animal:
+    ...
+
+
+class Cat(Animal):
+    ...
+
+
+# Test 1: to check Aggregate provider
+provider1: providers.Aggregate[str] = providers.Aggregate(
+    a=providers.Object("str1"),
+    b=providers.Object("str2"),
+)
+provider_a_1: providers.Provider[str] = provider1.a
+provider_b_1: providers.Provider[str] = provider1.b
+val1: str = provider1("a")
+
+provider1_set_non_string_keys: providers.Aggregate[str] = providers.Aggregate()
+provider1_set_non_string_keys.set_providers({Cat: providers.Object("str")})
+provider_set_non_string_1: providers.Provider[str] = provider1_set_non_string_keys.providers[Cat]
+
+provider1_new_non_string_keys: providers.Aggregate[str] = providers.Aggregate(
+    {Cat: providers.Object("str")},
+)
+factory_new_non_string_1: providers.Provider[str] = provider1_new_non_string_keys.providers[Cat]
+
+provider1_no_explicit_typing = providers.Aggregate(a=providers.Object("str"))
+provider1_no_explicit_typing_factory: providers.Provider[str] = provider1_no_explicit_typing.providers["a"]
+provider1_no_explicit_typing_object: str = provider1_no_explicit_typing("a")