Add the default value for the 'servers' array

The specification:

https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.1.md#oasObject

requires that if the 'servers' array is not provided or empty,
its default value is an array of a single Server Object
with 'url' of '/'.

openapi_core/servers.py

@@ -41,6 +41,9 @@ class ServersGenerator(object):
 
     def generate(self, servers_spec):
         servers_deref = self.dereferencer.dereference(servers_spec)
+        if not servers_deref:
+            yield Server('/')
+            return
         for server_spec in servers_deref:
             url = server_spec['url']
             variables_spec = server_spec.get('variables', {})
@@ -65,9 +68,6 @@ class ServerVariablesGenerator(object):
     def generate(self, variables_spec):
         variables_deref = self.dereferencer.dereference(variables_spec)
 
-        if not variables_deref:
-            return
-
         for variable_name, variable_spec in iteritems(variables_deref):
             default = variable_spec['default']
             enum = variable_spec.get('enum')

openapi_core/validators.py

@@ -1,5 +1,6 @@
 """OpenAPI core validators module"""
 from six import iteritems
+from yarl import URL
 
 from openapi_core.exceptions import (
     OpenAPIMappingError, MissingParameter, MissingBody, InvalidResponse,
@@ -51,6 +52,16 @@ class ResponseValidationResult(BaseValidationResult):
         self.headers = headers
 
 
+def get_operation_pattern(server_url, request_url_pattern):
+    """Return an updated request URL pattern with the server URL removed."""
+    if server_url[-1] == "/":
+        # operations have to start with a slash, so do not remove it
+        server_url = server_url[:-1]
+    if URL(server_url).is_absolute():
+        return request_url_pattern.replace(server_url, "", 1)
+    return URL(request_url_pattern).path_qs.replace(server_url, "", 1)
+
+
 class RequestValidator(object):
 
     def __init__(self, spec):
@@ -68,8 +79,9 @@ class RequestValidator(object):
             errors.append(exc)
             return RequestValidationResult(errors, body, parameters)
 
-        operation_pattern = request.full_url_pattern.replace(
-            server.default_url, '')
+        operation_pattern = get_operation_pattern(
+            server.default_url, request.full_url_pattern
+        )
 
         try:
             operation = self.spec.get_operation(
@@ -154,8 +166,9 @@ class ResponseValidator(object):
             errors.append(exc)
             return ResponseValidationResult(errors, data, headers)
 
-        operation_pattern = request.full_url_pattern.replace(
-            server.default_url, '')
+        operation_pattern = get_operation_pattern(
+            server.default_url, request.full_url_pattern
+        )
 
         try:
             operation = self.spec.get_operation(

requirements.txt

@@ -1,2 +1,3 @@
 openapi-spec-validator
 six
+yarl

tests/integration/data/v3.0/minimal.yaml

@@ -0,0 +1,10 @@
+openapi: "3.0.0"
+info:
+  title: Minimal valid OpenAPI specification
+  version: "0.1"
+paths:
+  /status:
+    get:
+      responses:
+        default:
+          description: Return the API status.

tests/integration/data/v3.0/minimal_with_servers.yaml

@@ -0,0 +1,12 @@
+openapi: "3.0.0"
+info:
+  title: Minimal valid OpenAPI specification with explicit 'servers' array
+  version: "0.1"
+servers:
+  - url: /
+paths:
+  /status:
+    get:
+      responses:
+        default:
+          description: Return the API status.

tests/integration/test_minimal.py

@@ -0,0 +1,49 @@
+import pytest
+
+from openapi_core.exceptions import InvalidOperation
+from openapi_core.shortcuts import create_spec
+from openapi_core.validators import RequestValidator
+from openapi_core.wrappers import MockRequest
+
+
+class TestMinimal(object):
+
+    servers = [
+        "http://minimal.test/",
+        "https://bad.remote.domain.net/",
+        "http://localhost",
+        "http://localhost:8080",
+        "https://u:p@a.b:1337"
+    ]
+
+    spec_paths = [
+        "data/v3.0/minimal_with_servers.yaml",
+        "data/v3.0/minimal.yaml"
+    ]
+
+    @pytest.mark.parametrize("server", servers)
+    @pytest.mark.parametrize("spec_path", spec_paths)
+    def test_hosts(self, factory, server, spec_path):
+        spec_dict = factory.spec_from_file(spec_path)
+        spec = create_spec(spec_dict)
+        validator = RequestValidator(spec)
+        request = MockRequest(server, "get", "/status")
+
+        result = validator.validate(request)
+
+        assert not result.errors
+
+    @pytest.mark.parametrize("server", servers)
+    @pytest.mark.parametrize("spec_path", spec_paths)
+    def test_invalid_operation(self, factory, server, spec_path):
+        spec_dict = factory.spec_from_file(spec_path)
+        spec = create_spec(spec_dict)
+        validator = RequestValidator(spec)
+        request = MockRequest(server, "get", "/nonexistent")
+
+        result = validator.validate(request)
+
+        assert len(result.errors) == 1
+        assert isinstance(result.errors[0], InvalidOperation)
+        assert result.body is None
+        assert result.parameters == {}