From d0b957760549710b90300b9a3a373d175238884c Mon Sep 17 00:00:00 2001
From: Carlton Gibson <carlton.gibson@noumenal.es>
Date: Wed, 8 Jan 2020 20:37:23 +0100
Subject: [PATCH] Return valid OpenAPI schema even when empty.

---
 rest_framework/schemas/openapi.py | 10 +---------
 tests/schemas/test_openapi.py     |  9 +++++++++
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/rest_framework/schemas/openapi.py b/rest_framework/schemas/openapi.py
index 58788bc23..aaeb2914c 100644
--- a/rest_framework/schemas/openapi.py
+++ b/rest_framework/schemas/openapi.py
@@ -35,12 +35,7 @@ class SchemaGenerator(BaseSchemaGenerator):
     def get_paths(self, request=None):
         result = {}
 
-        paths, view_endpoints = self._get_paths_and_endpoints(request)
-
-        # Only generate the path prefix for paths that will be included
-        if not paths:
-            return None
-
+        _, view_endpoints = self._get_paths_and_endpoints(request)
         for path, method, view in view_endpoints:
             if not self.has_view_permissions(path, method, view):
                 continue
@@ -62,9 +57,6 @@ class SchemaGenerator(BaseSchemaGenerator):
         self._initialise_endpoints()
 
         paths = self.get_paths(None if public else request)
-        if not paths:
-            return None
-
         schema = {
             'openapi': '3.0.2',
             'info': self.get_info(),
diff --git a/tests/schemas/test_openapi.py b/tests/schemas/test_openapi.py
index 03eb9de7a..83473be4b 100644
--- a/tests/schemas/test_openapi.py
+++ b/tests/schemas/test_openapi.py
@@ -707,6 +707,15 @@ class TestGenerator(TestCase):
         assert 'openapi' in schema
         assert 'paths' in schema
 
+    def test_schema_with_no_paths(self):
+        patterns = []
+        generator = SchemaGenerator(patterns=patterns)
+
+        request = create_request('/')
+        schema = generator.get_schema(request=request)
+
+        assert schema['paths'] == {}
+
     def test_schema_information(self):
         """Construction of the top level dictionary."""
         patterns = [