Added schema validation rule that ensures that interfaces are implemented.

src/Core/Core/Execution/Utilities/ValueCompletion.cs

@@ -6,7 +6,6 @@
 using HotChocolate.Properties;
 using HotChocolate.Types;
 using HotChocolate.Utilities;
-using HotChocolate.Configuration;
 
 namespace HotChocolate.Execution
 {
@@ -176,7 +175,8 @@ private static void CompleteCompositeType(
                     b.SetMessage(string.Format(
                         CultureInfo.InvariantCulture,
                         CoreResources.CompleteCompositeType_UnknownSchemaType,
-                        context.Value.GetType().GetTypeName())));
+                        result.GetType().GetTypeName(),
+                        type.NamedType().Name.Value)));
                 context.Value = null;
             }
             else

src/Core/Core/Properties/CoreResources.resx

@@ -1,17 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <root>
-  <!-- 
-    Microsoft ResX Schema 
-    
+  <!--
+    Microsoft ResX Schema
+
     Version 2.0
-    
-    The primary goals of this format is to allow a simple XML format 
-    that is mostly human readable. The generation and parsing of the 
-    various data types are done through the TypeConverter classes 
+
+    The primary goals of this format is to allow a simple XML format
+    that is mostly human readable. The generation and parsing of the
+    various data types are done through the TypeConverter classes
     associated with the data types.
-    
+
     Example:
-    
+
     ... ado.net/XML headers & schema ...
     <resheader name="resmimetype">text/microsoft-resx</resheader>
     <resheader name="version">2.0</resheader>
@@ -26,40 +26,43 @@
         <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
         <comment>This is a comment</comment>
     </data>
-                
-    There are any number of "resheader" rows that contain simple 
+
+    There are any number of "resheader" rows that contain simple
     name/value pairs.
-    
-    Each data row contains a name, and value. The row also contains a 
-    type or mimetype. Type corresponds to a .NET class that support 
-    text/value conversion through the TypeConverter architecture. 
-    Classes that don't support this are serialized and stored with the 
+
+    Each data row contains a name, and value. The row also contains a
+    type or mimetype. Type corresponds to a .NET class that support
+    text/value conversion through the TypeConverter architecture.
+    Classes that don't support this are serialized and stored with the
     mimetype set.
-    
-    The mimetype is used for serialized objects, and tells the 
-    ResXResourceReader how to depersist the object. This is currently not 
+
+    The mimetype is used for serialized objects, and tells the
+    ResXResourceReader how to depersist the object. This is currently not
     extensible. For a given mimetype the value must be set accordingly:
-    
-    Note - application/x-microsoft.net.object.binary.base64 is the format 
-    that the ResXResourceWriter will generate, however the reader can 
+
+    Note - application/x-microsoft.net.object.binary.base64 is the format
+    that the ResXResourceWriter will generate, however the reader can
     read any of the formats listed below.
-    
+
     mimetype: application/x-microsoft.net.object.binary.base64
-    value   : The object must be serialized with 
+    value   : The object must be serialized with
             : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
             : and then encoded with base64 encoding.
-    
+
     mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with 
+    value   : The object must be serialized with
             : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
             : and then encoded with base64 encoding.
 
     mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array 
+    value   : The object must be serialized into a byte array
             : using a System.ComponentModel.TypeConverter
             : and then encoded with base64 encoding.
     -->
-  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+  <xsd:schema id="root"
+    xmlns=""
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+    xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
     <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
     <xsd:element name="root" msdata:IsDataSet="true">
       <xsd:complexType>
@@ -118,7 +121,7 @@
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <data name="CompleteCompositeType_UnknownSchemaType" xml:space="preserve">
-    <value>Could not resolve the schema type from `{0}`.</value>
+    <value>Could not resolve the actual object type from `{0}` for the abstract type `{1}`.</value>
   </data>
   <data name="CompleteLeadType_UndefinedError" xml:space="preserve">
     <value>Undefined scalar field serialization error.</value>
@@ -214,4 +217,4 @@ The maximum allowed query complexity is {1}.</value>
   <data name="RequestTimeoutMiddleware_Timeout" xml:space="preserve">
     <value>Execution timeout has been exceeded.</value>
   </data>
-</root>
+</root>

src/Core/Types.Tests/Configuration/TypeInitializerTests.cs

@@ -34,7 +34,7 @@ public void Register_SchemaType_ClrTypeExists()
                 t => t is FooType);
 
             // act
-            typeInitializer.Initialize(() => null);
+            typeInitializer.Initialize(() => null, new SchemaOptions());
 
             // assert
             bool exists = typeInitializer.Types.TryGetValue(
@@ -79,7 +79,7 @@ public void Register_ClrType_InferSchemaTypes()
                 t => t is ObjectType<Foo>);
 
             // act
-            typeInitializer.Initialize(() => null);
+            typeInitializer.Initialize(() => null, new SchemaOptions());
 
             // assert
             bool exists = typeInitializer.Types.TryGetValue(
@@ -105,6 +105,61 @@ public void Register_ClrType_InferSchemaTypes()
                 .MatchSnapshot(new SnapshotNameExtension("BarType"));
         }
 
+        [Fact]
+        public void Initializer_SchemaResolver_Is_Null()
+        {
+            // arrange
+            var initialTypes = new List<ITypeReference>();
+            initialTypes.Add(new ClrTypeReference(
+                typeof(Foo),
+                TypeContext.Output));
+
+            var serviceProvider = new EmptyServiceProvider();
+
+            var typeInitializer = new TypeInitializer(
+                serviceProvider,
+                DescriptorContext.Create(),
+                initialTypes,
+                new List<Type>(),
+                new Dictionary<string, object>(),
+                null,
+                t => t is ObjectType<Foo>);
+
+            // act
+            Action action =
+                () => typeInitializer.Initialize(null, new SchemaOptions());
+
+            // assert
+            Assert.Throws<ArgumentNullException>(action);
+        }
+
+        [Fact]
+        public void Initializer_SchemaOptions_Are_Null()
+        {
+            // arrange
+            var initialTypes = new List<ITypeReference>();
+            initialTypes.Add(new ClrTypeReference(
+                typeof(Foo),
+                TypeContext.Output));
+
+            var serviceProvider = new EmptyServiceProvider();
+
+            var typeInitializer = new TypeInitializer(
+                serviceProvider,
+                DescriptorContext.Create(),
+                initialTypes,
+                new List<Type>(),
+                new Dictionary<string, object>(),
+                null,
+                t => t is ObjectType<Foo>);
+
+            // act
+            Action action =
+                () => typeInitializer.Initialize(() => null, null);
+
+            // assert
+            Assert.Throws<ArgumentNullException>(action);
+        }
 
         public class FooType
             : ObjectType<Foo>

src/Core/Types.Tests/SchemaBuilderTests.cs

@@ -951,6 +951,88 @@ public void Could_Not_Resolve_Type()
                 Assert.Throws<SchemaException>(action).Message);
         }
 
+        [Fact]
+        public void Interface_Without_Implementation()
+        {
+            // arrange
+            // act
+            Action action = () => SchemaBuilder.New()
+                .AddDocumentFromString(@"
+                    type Query {
+                        foo : Bar
+                    }
+                    interface Bar {
+                        baz: String
+                    }")
+                .AddResolver("Query", "foo", "bar")
+                .Create();
+
+            // assert
+            Assert.Equal(
+                "There is no object type implementing interface `Bar`. - Type: Bar",
+                Assert.Throws<SchemaException>(action).Message);
+        }
+
+        [Fact]
+        public void Interface_Without_Implementation_Not_Strict()
+        {
+            // arrange
+            // act
+            ISchema schema = SchemaBuilder.New()
+                .AddDocumentFromString(@"
+                    type Query {
+                        foo : Bar
+                    }
+                    interface Bar {
+                        baz: String
+                    }")
+                .AddResolver("Query", "foo", "bar")
+                .ModifyOptions(o => o.StrictValidation = false)
+                .Create();
+
+            // assert
+            Assert.NotNull(schema);
+        }
+
+        [Fact]
+        public async Task Execute_Agains_Interface_Without_Impl_Field()
+        {
+            // arrange
+            ISchema schema = SchemaBuilder.New()
+                .AddDocumentFromString(@"
+                    type Query {
+                        foo : Bar
+                    }
+                    interface Bar {
+                        baz: String
+                    }")
+                .AddResolver("Query", "foo", "bar")
+                .ModifyOptions(o => o.StrictValidation = false)
+                .Create();
+
+            IQueryExecutor executor = schema.MakeExecutable();
+
+            // act
+            IExecutionResult result =
+                await executor.ExecuteAsync("{ foo { baz } }");
+
+            // assert
+            result.ToJson().MatchSnapshot();
+        }
+
+        [Fact]
+        public void Abstract_Classes_Are_Allowed_As_Object_Types()
+        {
+            // arrange
+            // act
+            ISchema schema = SchemaBuilder.New()
+                .AddQueryType<AbstractQuery>()
+                .Create();
+
+            // assert
+            schema.ToString().MatchSnapshot();
+        }
+
         public class DynamicFooType
             : ObjectType
         {
@@ -1055,5 +1137,17 @@ public class QueryWithIntField
         {
             public int Foo { get; set; }
         }
+
+        public abstract class AbstractQuery
+        {
+            public string Foo { get; set; }
+
+            public AbstractChild Object { get; set; }
+        }
+
+        public abstract class AbstractChild
+        {
+            public string Foo { get; set; }
+        }
     }
 }

src/Core/Types.Tests/SchemaFirstTests.cs

@@ -23,6 +23,7 @@ public async Task DescriptionsAreCorrectlyRead()
                 source,
                 c =>
                 {
+                    c.Options.StrictValidation = false;
                     c.Use(next => context => next(context));
                 });
 

src/Core/Types.Tests/Types/Directives/CostDirectiveTypeTests.cs

@@ -108,6 +108,8 @@ public void AnnotateCostToInterfaceFieldCodeFirst()
                             .Type<StringType>()
                             .Cost(5)));
 
+                    t.Options.StrictValidation = false;
+
                     t.Use(next => context => Task.CompletedTask);
                 });
 
@@ -139,6 +141,8 @@ public void AnnotateCostToInterfaceFieldCodeFirstOneMultiplier()
                             .Type<StringType>()
                             .Cost(5, "a")));
 
+                    t.Options.StrictValidation = false;
+
                     t.Use(next => context => Task.CompletedTask);
                 });
 
@@ -172,6 +176,8 @@ public void AnnotateCostToInterfaceFieldCodeFirstTwoMultiplier()
                             .Type<StringType>()
                             .Cost(5, "a", "b")));
 
+                    t.Options.StrictValidation = false;
+
                     t.Use(next => context => Task.CompletedTask);
                 });
 
@@ -223,7 +229,11 @@ interface IQuery {
                         @cost(complexity: 5 multipliers: [""a""])
                 }
                 ",
-                t => t.Use(next => context => Task.CompletedTask));
+                t =>
+                {
+                    t.Use(next => context => Task.CompletedTask);
+                    t.Options.StrictValidation = false;
+                });
 
             InterfaceType queryInterface = schema.GetType<InterfaceType>("IQuery");
             IDirective directive = queryInterface.Fields["field"].Directives