Add ManualSchema class

Author: carltongibson

docs/api-guide/schemas.md

@@ -463,6 +463,21 @@ Return a list of `coreapi.Link()` instances, as returned by the `get_schema_fiel
 
 Return a list of `coreapi.Link()` instances, as returned by the `get_schema_fields()` method of any filter classes used by the view.
 
+
+## ManualSchema
+
+`APIViewSchemaDescriptor` subclass for specifying a manual schema.
+
+    class MyView(APIView):
+      schema = ManualSchema(coreapi.Link(
+        url='/example/',
+        action='get',
+        fields=[]
+      ))
+
+The `ManualSchema` constructor takes a single parameter `link`,
+the `coreapi.Link` instance for the view.
+
 ---
 
 ## Core API

rest_framework/schemas.py

@@ -500,6 +500,18 @@ def get_encoding(self, path, method):
 APIView.schema = APIViewSchemaDescriptor()
 
 
+class ManualSchema(APIViewSchemaDescriptor):
+    """
+    Overrides get_link to return manually specified schema.
+    """
+    def __init__(self, link):
+        assert isinstance(link, coreapi.Link)
+        self._link = link
+
+    def get_link(self, *args):
+        return self._link
+
+
 class SchemaGenerator(object):
     # Map HTTP methods onto actions.
     default_mapping = {

tests/test_schemas.py

@@ -12,7 +12,7 @@
 from rest_framework.request import Request
 from rest_framework.routers import DefaultRouter
 from rest_framework.schemas import (
-    APIViewSchemaDescriptor, SchemaGenerator, get_schema_view
+    APIViewSchemaDescriptor, ManualSchema, SchemaGenerator, get_schema_view
 )
 from rest_framework.test import APIClient, APIRequestFactory
 from rest_framework.views import APIView
@@ -512,3 +512,18 @@ def test_get_link_requires_instance(self):
         descriptor = APIView.schema  # Accessed from class
         with pytest.raises(AssertionError):
             descriptor.get_link(None, None, None)  # ???: Do the dummy arguments require a tighter assert?
+
+    def test_view_with_manual_schema(self):
+
+        expected = coreapi.Link(
+            url='/example/',
+            action='get',
+            fields=[]
+        )
+
+        class CustomView(APIView):
+            schema = ManualSchema(expected)
+
+        view = CustomView()
+        link = view.schema.get_link()
+        assert link == expected