fix(valid-expect): validate async expect calls

Resolves jest-community#54

docs/rules/valid-expect.md

@@ -33,6 +33,19 @@ expect('something', 'else');
 expect('something');
 expect(true).toBeDefined;
 expect(Promise.resolve('hello')).resolves;
+
+// 👎 expect(Promise).resolves is not returned
+test('foo', () => {
+  expect(Promise.resolve('hello')).resolves.toBeDefined();
+});
+// 👎 expect(Promise).resolves is not awaited
+test('foo', async () => {
+  expect(Promise.resolve('hello')).resolves.toBeDefined();
+});
+// 👎 expect(awaited Promise) should not use .resolves or .rejects property
+test('foo', async () => {
+  expect(await Promise.resolve('hello')).resolves.toBeDefined();
+});
 ```
 
 The following patterns are not warnings:
@@ -42,4 +55,23 @@ expect('something').toEqual('something');
 expect([1, 2, 3]).toEqual([1, 2, 3]);
 expect(true).toBeDefined();
 expect(Promise.resolve('hello')).resolves.toEqual('hello');
+
+// 👍 expect(Promise).resolves is returned
+test('foo', () => {
+  return expect(Promise.resolve('hello')).resolves.toBeDefined();
+});
+// 👍 expect(Promise).resolves is awaited
+test('foo', async () => {
+  await expect(Promise.resolve('hello')).resolves.toBeDefined();
+});
+// 👍 expect(Promise).rejects is implicitly returned
+test('foo', () => expect(Promise.reject('hello')).rejects.toBeDefined());
+// 👍 expect(awaited Promise) is not used with .resolves
+test('foo', async () => {
+  expect(await Promise.resolve('hello')).toBeDefined();
+});
+// 👍 expect(awaited Promise) is not used with .rejects
+test('foo', async () => {
+  expect(await Promise.reject('hello')).toBeDefined();
+});
 ```

package.json

@@ -73,5 +73,8 @@
   },
   "commitlint": {
     "extends": ["@commitlint/config-conventional"]
+  },
+  "dependencies": {
+    "lodash.get": "^4.4.2"
   }
 }

rules/__tests__/valid-expect.test.js

@@ -3,16 +3,24 @@
 const RuleTester = require('eslint').RuleTester;
 const rule = require('../valid-expect');
 
-const ruleTester = new RuleTester();
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 8,
+  },
+});
 
 ruleTester.run('valid-expect', rule, {
   valid: [
     'expect("something").toEqual("else");',
     'expect(true).toBeDefined();',
     'expect([1, 2, 3]).toEqual([1, 2, 3]);',
     'expect(undefined).not.toBeDefined();',
-    'expect(Promise.resolve(2)).resolves.toBeDefined();',
-    'expect(Promise.reject(2)).rejects.toBeDefined();',
+    'test("foo", () => { return expect(Promise.resolve(2)).resolves.toBeDefined(); });',
+    'test("foo", async () => { await expect(Promise.reject(2)).rejects.toBeDefined(); });',
+    'test("foo", () => expect(Promise.resolve(2)).resolves.toBeDefined());',
+    'test("foo", async () => await expect(Promise.reject(2)).rejects.toBeDefined());',
+    'test("foo", async () => { expect(await Promise.resolve(2)).toBeDefined(); });',
+    'test("foo", async () => { expect(await Promise.reject(2)).toBeDefined(); });',
   ],
 
   invalid: [
@@ -131,5 +139,39 @@ ruleTester.run('valid-expect', rule, {
         },
       ],
     },
+    {
+      code:
+        'test("foo", () => { expect(Promise.resolve(2)).resolves.toBeDefined(); });',
+      errors: [{ message: "Must return or await 'expect.resolves' statement" }],
+    },
+    {
+      code:
+        'test("foo", async () => { expect(Promise.resolve(2)).resolves.toBeDefined(); });',
+      errors: [{ message: "Must await 'expect.resolves' statement" }],
+    },
+    {
+      code:
+        'test("foo", () => { expect(Promise.reject(2)).rejects.toBeDefined(); });',
+      errors: [{ message: "Must return or await 'expect.rejects' statement" }],
+    },
+    {
+      code:
+        'test("foo", async () => { expect(Promise.reject(2)).rejects.toBeDefined(); });',
+      errors: [{ message: "Must await 'expect.rejects' statement" }],
+    },
+    {
+      code:
+        'test("foo", async () => { expect(await Promise.resolve(2)).resolves.toBeDefined(); });',
+      errors: [
+        { message: "Cannot use 'resolves' with an awaited expect expression" },
+      ],
+    },
+    {
+      code:
+        'test("foo", async () => { expect(await Promise.reject(2)).rejects.toBeDefined(); });',
+      errors: [
+        { message: "Cannot use 'rejects' with an awaited expect expression" },
+      ],
+    },
   ],
 });

rules/valid-expect.js

@@ -5,19 +5,72 @@
  * MIT license, Tom Vincent.
  */
 
-const getDocsUrl = require('./util').getDocsUrl;
+const get = require('lodash.get');
+const util = require('./util');
 
 const expectProperties = ['not', 'resolves', 'rejects'];
 
 module.exports = {
   meta: {
     docs: {
-      url: getDocsUrl(__filename),
+      url: util.getDocsUrl(__filename),
     },
   },
   create(context) {
+    function validateAsyncExpects(node) {
+      const callback = node.arguments[1];
+      if (
+        callback &&
+        util.isFunction(callback) &&
+        callback.body.type === 'BlockStatement'
+      ) {
+        callback.body.body
+          .filter(node => node.type === 'ExpressionStatement')
+          .filter(node => {
+            const objectName = get(
+              node,
+              'expression.callee.object.object.callee.name'
+            );
+            const propertyName = get(
+              node,
+              'expression.callee.object.property.name'
+            );
+
+            return (
+              node.expression.type === 'CallExpression' &&
+              objectName === 'expect' &&
+              (propertyName === 'resolves' || propertyName === 'rejects')
+            );
+          })
+          .forEach(node => {
+            const propertyName = get(
+              node,
+              'expression.callee.object.property.name'
+            );
+            const isAwaitInsideExpect =
+              get(node, 'expression.callee.object.object.arguments[0].type') ===
+              'AwaitExpression';
+
+            context.report({
+              node,
+              message: isAwaitInsideExpect
+                ? "Cannot use '{{ propertyName }}' with an awaited expect expression"
+                : callback.async
+                  ? "Must await 'expect.{{ propertyName }}' statement"
+                  : "Must return or await 'expect.{{ propertyName }}' statement",
+              data: { propertyName },
+            });
+          });
+      }
+    }
+
     return {
       CallExpression(node) {
+        if (util.isTestCase(node)) {
+          validateAsyncExpects(node);
+          return;
+        }
+
         const calleeName = node.callee.name;
 
         if (calleeName === 'expect') {

yarn.lock

@@ -3559,6 +3559,10 @@ lodash.camelcase@4.3.0:
   version "4.3.0"
   resolved "https://registry.yarnpkg.com/lodash.camelcase/-/lodash.camelcase-4.3.0.tgz#b28aa6288a2b9fc651035c7711f65ab6190331a6"
 
+lodash.get@^4.4.2:
+  version "4.4.2"
+  resolved "https://registry.yarnpkg.com/lodash.get/-/lodash.get-4.4.2.tgz#2d177f652fa31e939b4438d5341499dfa3825e99"
+
 lodash.kebabcase@4.1.1:
   version "4.1.1"
   resolved "https://registry.yarnpkg.com/lodash.kebabcase/-/lodash.kebabcase-4.1.1.tgz#8489b1cb0d29ff88195cceca448ff6d6cc295c36"