From 4ac985a5a3f550b7a7bdcc06e87c443b27f1ba5b Mon Sep 17 00:00:00 2001
From: "David R. Myers" <davidrmyersii@gmail.com>
Date: Thu, 12 May 2022 13:08:13 -0400
Subject: [PATCH] Fix .resolves and .rejects expectations

The promise helpers, .resolves and .rejects, were throwing errors when the returned object could not be serialized. Specifically, this would happen when using dynamic imports (e.g. `expect(() => import('./some_module')).resolves`). Additionally, the .resolves helper did not support a function argument even though a function was expected.
---
 .../src/integrations/chai/jest-expect.ts      | 13 ++++++--
 packages/vitest/src/integrations/utils.ts     |  9 +++++
 test/core/test/jest-expect.test.ts            | 33 +++++++++++++++++++
 3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/packages/vitest/src/integrations/chai/jest-expect.ts b/packages/vitest/src/integrations/chai/jest-expect.ts
index df1bd4c35b4a..96a3291cff0c 100644
--- a/packages/vitest/src/integrations/chai/jest-expect.ts
+++ b/packages/vitest/src/integrations/chai/jest-expect.ts
@@ -2,6 +2,7 @@ import c from 'picocolors'
 import type { EnhancedSpy } from '../spy'
 import { isMockFunction } from '../spy'
 import { addSerializer } from '../snapshot/port/plugins'
+import { toString } from '../utils'
 import type { Constructable, Test } from '../../types'
 import { assertTypes } from '../../utils'
 import { unifiedDiff } from '../../node/diff'
@@ -550,6 +551,10 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
     utils.flag(this, 'promise', 'resolves')
     utils.flag(this, 'error', new Error('resolves'))
     const obj = utils.flag(this, 'object')
+
+    if (typeof obj?.then !== 'function')
+      throw new TypeError(`You must provide a Promise to expect() when using .resolves, not '${typeof obj}'.`)
+
     const proxy: any = new Proxy(this, {
       get: (target, key, receiver) => {
         const result = Reflect.get(target, key, receiver)
@@ -564,7 +569,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
               return result.call(this, ...args)
             },
             (err: any) => {
-              throw new Error(`promise rejected "${err}" instead of resolving`)
+              throw new Error(`promise rejected "${toString(err)}" instead of resolving`)
             },
           )
         }
@@ -579,6 +584,10 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
     utils.flag(this, 'error', new Error('rejects'))
     const obj = utils.flag(this, 'object')
     const wrapper = typeof obj === 'function' ? obj() : obj // for jest compat
+
+    if (typeof wrapper?.then !== 'function')
+      throw new TypeError(`You must provide a Promise to expect() when using .rejects, not '${typeof wrapper}'.`)
+
     const proxy: any = new Proxy(this, {
       get: (target, key, receiver) => {
         const result = Reflect.get(target, key, receiver)
@@ -589,7 +598,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
         return async (...args: any[]) => {
           return wrapper.then(
             (value: any) => {
-              throw new Error(`promise resolved "${value}" instead of rejecting`)
+              throw new Error(`promise resolved "${toString(value)}" instead of rejecting`)
             },
             (err: any) => {
               utils.flag(this, 'object', err)
diff --git a/packages/vitest/src/integrations/utils.ts b/packages/vitest/src/integrations/utils.ts
index cc9da21c0dca..dbf0ee9f1f93 100644
--- a/packages/vitest/src/integrations/utils.ts
+++ b/packages/vitest/src/integrations/utils.ts
@@ -5,3 +5,12 @@ export function getRunningMode() {
 export function isWatchMode() {
   return getRunningMode() === 'watch'
 }
+
+export function toString(value: any) {
+  try {
+    return `${value}`
+  }
+  catch (_error) {
+    return 'unknown'
+  }
+}
diff --git a/test/core/test/jest-expect.test.ts b/test/core/test/jest-expect.test.ts
index bcd0cca4a0ef..9d22d1d964a6 100644
--- a/test/core/test/jest-expect.test.ts
+++ b/test/core/test/jest-expect.test.ts
@@ -437,6 +437,19 @@ describe('async expect', () => {
     await expect((async () => 'true')()).resolves.not.toBe('true22')
   })
 
+  it('throws an error on .resolves when the argument is not a promise', () => {
+    expect.assertions(2)
+
+    const expectedError = new TypeError('You must provide a Promise to expect() when using .resolves, not \'number\'.')
+
+    try {
+      expect(1).resolves.toEqual(2)
+    }
+    catch (error) {
+      expect(error).toEqual(expectedError)
+    }
+  })
+
   it.fails('failed to resolve', async () => {
     await expect((async () => {
       throw new Error('err')
@@ -471,6 +484,26 @@ describe('async expect', () => {
   it.fails('failed to reject', async () => {
     await expect((async () => 'test')()).rejects.toBe('test')
   })
+
+  it('throws an error on .rejects when the argument (or function result) is not a promise', () => {
+    expect.assertions(4)
+
+    const expectedError = new TypeError('You must provide a Promise to expect() when using .rejects, not \'number\'.')
+
+    try {
+      expect(1).rejects.toEqual(2)
+    }
+    catch (error) {
+      expect(error).toEqual(expectedError)
+    }
+
+    try {
+      expect(() => 1).rejects.toEqual(2)
+    }
+    catch (error) {
+      expect(error).toEqual(expectedError)
+    }
+  })
 })
 
 it('timeout', () => new Promise(resolve => setTimeout(resolve, 500)))