public async Task ExecuteOperationMiddleware_Mutation_ExecutedSerially()
        {
            // arrange
            var state = 0;

            var schema = Schema.Create(
                FileResource.Open("MutationExecutionSchema.graphql"),
                cnf =>
            {
                cnf.BindResolver(() => state)
                .To("Query", "state");
                cnf.BindResolver(() => state)
                .To("CurrentState", "theNumber");
                cnf.BindResolver(
                    ctx => state = ctx.Argument <int>("newNumber"))
                .To("Mutation", "changeTheNumber");
            });

            DocumentNode query = Parser.Default.Parse(
                FileResource.Open("MutationExecutionQuery.graphql"));

            OperationDefinitionNode operation = query.Definitions
                                                .OfType <OperationDefinitionNode>()
                                                .FirstOrDefault();

            var request = new QueryRequest("{ a }").ToReadOnly();

            var services = new DictionaryServiceProvider(
                new KeyValuePair <Type, object>(
                    typeof(IErrorHandler),
                    ErrorHandler.Default));

            var context = new QueryContext(schema, services, request)
            {
                Document  = query,
                Operation = operation
            };

            var options          = new QueryExecutionOptions();
            var strategyResolver = new ExecutionStrategyResolver(options);

            var middleware = new ExecuteOperationMiddleware(
                c => Task.CompletedTask,
                strategyResolver,
                new Cache <DirectiveLookup>(10));

            // act
            await middleware.InvokeAsync(context);

            // assert
            Assert.NotNull(context.Result);
            context.Result.Snapshot();
        }
        public async Task ExecuteOperationMiddleware_Mutation_ExecutedSerially()
        {
            // arrange
            var state = 0;

            var schema = Schema.Create(
                FileResource.Open("MutationExecutionSchema.graphql"),
                cnf =>
            {
                cnf.BindResolver(() => state)
                .To("Query", "state");
                cnf.BindResolver(() => state)
                .To("CurrentState", "theNumber");
                cnf.BindResolver(
                    ctx => state = ctx.Argument <int>("newNumber"))
                .To("Mutation", "changeTheNumber");
            });

            DocumentNode query = Parser.Default.Parse(
                FileResource.Open("MutationExecutionQuery.graphql"));

            OperationDefinitionNode operationNode = query.Definitions
                                                    .OfType <OperationDefinitionNode>()
                                                    .FirstOrDefault();

            var operation = new Operation
                            (
                query,
                operationNode,
                new VariableValueBuilder(
                    schema,
                    operationNode)
                .CreateValues(new Dictionary <string, object>()),
                schema.MutationType,
                null
                            );

            IReadOnlyQueryRequest request = new QueryRequest("{ a }");

            var observable = new DiagnosticListener("Foo");

            var services = new DictionaryServiceProvider(
                new KeyValuePair <Type, object>(
                    typeof(IErrorHandler),
                    ErrorHandler.Default),
                new KeyValuePair <Type, object>(
                    typeof(DiagnosticListener),
                    observable),
                new KeyValuePair <Type, object>(
                    typeof(DiagnosticSource),
                    observable));

            var context = new QueryContext
                          (
                schema,
                services.CreateRequestServiceScope(),
                request,
                fs => fs.Field.Middleware
                          )
            {
                Document  = query,
                Operation = operation
            };

            var options          = new QueryExecutionOptions();
            var strategyResolver = new ExecutionStrategyResolver(options);

            var diagnostics = new QueryExecutionDiagnostics(
                new DiagnosticListener("Foo"),
                new IDiagnosticObserver[0],
                TracingPreference.Never);

            var middleware = new ExecuteOperationMiddleware(
                c => Task.CompletedTask,
                strategyResolver,
                new Cache <DirectiveMiddlewareCompiler>(10),
                diagnostics);

            // act
            await middleware.InvokeAsync(context);

            // assert
            Assert.NotNull(context.Result);
            context.Result.Snapshot();
        }