Enable more Flow lint checks

.flowconfig

@@ -26,12 +26,12 @@
 
 [lints]
 sketchy-null-bool=off
-sketchy-null-string=off
+sketchy-null-string=error
 sketchy-null-number=error
 sketchy-null-mixed=off
 sketchy-number=error
 untyped-type-import=error
-nonstrict-import=off
+nonstrict-import=error
 untyped-import=off
 unclear-type=off
 deprecated-type=error

src/__tests__/http-test.js

@@ -35,7 +35,7 @@ const QueryRootType = new GraphQLObjectType({
       args: {
         who: { type: GraphQLString },
       },
-      resolve: (root, { who }) => 'Hello ' + ((who: any) || 'World'),
+      resolve: (root, args) => 'Hello ' + (args.who || 'World'),
     },
     thrower: {
       type: GraphQLString,
@@ -411,7 +411,7 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
             fields: {
               test: {
                 type: GraphQLString,
-                resolve: (obj, args, context) => (context: any).foo,
+                resolve: (obj, args, context) => context.foo,
               },
             },
           }),
@@ -2023,7 +2023,7 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
     });
 
     describe('Custom execute', () => {
-      it('allow to replace default execute.', async () => {
+      it('allow to replace default execute', async () => {
         const app = server();
 
         let seenExecuteArgs;
@@ -2035,9 +2035,14 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
             schema: TestSchema,
             async customExecuteFn(args) {
               seenExecuteArgs = args;
-              const result: any = await Promise.resolve(execute(args));
-              result.data.test2 = 'Modification';
-              return result;
+              const result = await Promise.resolve(execute(args));
+              return {
+                ...result,
+                data: {
+                  ...result.data,
+                  test2: 'Modification',
+                },
+              };
             },
           })),
         );
@@ -2156,7 +2161,7 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
             schema: TestSchema,
             customFormatErrorFn: () => null,
             extensions({ result }) {
-              return { preservedErrors: (result: any).errors };
+              return { preservedResult: { ...result } };
             },
           }),
         );
@@ -2172,13 +2177,16 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
           data: { thrower: null },
           errors: [null],
           extensions: {
-            preservedErrors: [
-              {
-                message: 'Throws!',
-                locations: [{ line: 1, column: 2 }],
-                path: ['thrower'],
-              },
-            ],
+            preservedResult: {
+              data: { thrower: null },
+              errors: [
+                {
+                  message: 'Throws!',
+                  locations: [{ line: 1, column: 2 }],
+                  path: ['thrower'],
+                },
+              ],
+            },
           },
         });
       });

src/index.js

@@ -164,7 +164,7 @@ export type RequestInfo = {|
   /**
    * The result of executing the operation.
    */
-  result: ?mixed,
+  result: ?ExecutionResult,
 
   /**
    * A value to pass as the context to the graphql() function.
@@ -254,7 +254,7 @@ function graphqlHTTP(options: Options): Middleware {
 
         // If there is no query, but GraphiQL will be displayed, do not produce
         // a result, otherwise return a 400: Bad Request.
-        if (!query) {
+        if (query == null) {
           if (showGraphiQL) {
             return null;
           }
@@ -469,7 +469,7 @@ function parseGraphQLParams(
 
   // Parse the variables if needed.
   let variables = urlData.variables || bodyData.variables;
-  if (variables && typeof variables === 'string') {
+  if (typeof variables === 'string') {
     try {
       variables = JSON.parse(variables);
     } catch (error) {

src/parseBody.js

@@ -37,7 +37,7 @@ export async function parseBody(
   }
 
   // Already parsed body we didn't recognise? Parse nothing.
-  if (body) {
+  if (body != null) {
     return {};
   }
 

src/renderGraphiQL.js

@@ -19,7 +19,9 @@ export type GraphiQLOptions = {|
 
 // Ensures string values are safe to be used within a <script> tag.
 function safeSerialize(data) {
-  return data ? JSON.stringify(data).replace(/\//g, '\\/') : 'undefined';
+  return data != null
+    ? JSON.stringify(data).replace(/\//g, '\\/')
+    : 'undefined';
 }
 
 // Implemented as Babel transformation, see ../resources/load-staticly-from-npm.js
@@ -34,12 +36,10 @@ declare function loadFileStaticlyFromNPM(npmPath: string): string;
  */
 export function renderGraphiQL(data: GraphiQLData): string {
   const queryString = data.query;
-  const variablesString = data.variables
-    ? JSON.stringify(data.variables, null, 2)
-    : null;
-  const resultString = data.result
-    ? JSON.stringify(data.result, null, 2)
-    : null;
+  const variablesString =
+    data.variables != null ? JSON.stringify(data.variables, null, 2) : null;
+  const resultString =
+    data.result != null ? JSON.stringify(data.result, null, 2) : null;
   const operationName = data.operationName;
   const defaultQuery = data.options.defaultQuery;