我需要測驗'readline.createInterface'。
下面是我需要測驗的代碼：
private createReadStreamSafe(filePath: string): Promise<fs.ReadStream> {
return new Promise((resolve, reject) => {
const fileStream = fs.createReadStream(filePath)
console.log('file Stream')
fileStream
.on('error', () => {
reject('create read stream error')
})
.on('open', () => {
resolve(fileStream)
})
})
}
async start() {
const fileStream = await this.createReadStreamSafe(this.filePath)
const rl = readline.createInterface({
input: fileStream,
output: process.stdout,
terminal: false
})
for await (const line of rl) {
...
}
}
我嘗試了以下代碼：
it('should work', async () => {
const mockedReadStream = new Readable()
jest.spyOn(fs, 'createReadStream').mockReturnValue(mockedReadStream as any)
jest.spyOn(readline, 'createInterface').mockImplementation(() => {
const lines = ['text', 'text2', 'text3']
return {
[Symbol.asyncIterator]() {
return {
i: 0,
next: () => {
if (this.i < 3) {
return Promise.resolve({ value: lines[this.i ], done: false })
}
return Promise.resolve({ done: true })
}
}
}
} as any
})
const app = new App('myFile.txt')
let promise = app.start()
mockedReadStream.emit('open')
await expect(promise).resolves.toBe(undefined)
})
但是永遠不會到達以下代碼
for await (const line of rl) {
...
}
有沒有辦法模擬readline.createInterface然后它與for await (const line of rl) 一起使用？
uj5u.com熱心網友回復：
問題是：在測驗期間沒有觸發異步可迭代物件。
解決方案，我們可以在模擬中使用一個陣列，如下所示：
jest.spyOn(readline, 'createInterface').mockImplementationOnce(() => {
return ['text1', 'text2'] as any
})
因為 for await (const item of iterable) 適用于異步可迭代物件以及同步可迭代物件。使用同步迭代器，它們將自動執行。
轉載請註明出處，本文鏈接：https://www.uj5u.com/ruanti/389711.html