Question

我继续使用流类型和jest获取此错误：

TypeError: Cannot read property 'returnType' of undefined

  at builder (src/index.js:22:195)
  at Object.<anonymous> (__test__/index.spec.js:6:53)
  at process._tickCallback (internal/process/next_tick.js:103:7)

以下是我的整个设置：

应用程序代码：

// @flow
type BuilderReturnType = {
    path: string,
    query: string
}

type BuilderOptionsType = {
    returnType?: string
}

export default function builder(path: string, {returnType = 'object'}: BuilderOptionsType): BuilderReturnType {
    const query = {};
    let queryResult = null;
    if (returnType === 'string') {
        queryResult = doSomething(query);
    }
    return {
        path,
        query: queryResult !== null ? queryResult : query
    }
}

.babelrc config：

{
    "presets": [
        "es2015", "jest"
    ],
    "plugins": [
        "transform-object-rest-spread",
        "transform-flow-strip-types"
    ],
    "env": {
        "test": {
            "presets": [
                "es2015", "jest"
            ],
            "plugins": [
                "transform-object-rest-spread",
                "transform-flow-strip-types"
            ]
        }
    }
}

jest.json config：

{
  "bail": true,
  "verbose": true,
  "collectCoverage": true,
  "coverageDirectory": "./coverage",
  "coverageThreshold": {
    "global": {
      "branches": 100,
      "functions": 100,
      "lines": 100,
      "statements": 100
    }
  },
  "transform": {
    "^.+\\.js$": "<rootDir>/node_modules/babel-jest"
  }
}

似乎同时使用解构和流类型的方法签名存在问题（BuilderOptionsType对象）：

    export default function builder(path: string, {returnType = 'object'}: BuilderOptionsType): BuilderReturnType { ... }

如果我将{returnType = 'object'}更改为options然后在方法中进行解构，则它似乎完全正常。考虑到这一点，这是允许同时使用jest和flow类型的唯一方法吗？我更喜欢能够在签名中而不是在方法体内进行解构。

Answer 1

查看错误，您可能无法将第二个参数传递给函数。如果您致电builder('foo')，您将尝试从returnType解构undefined。

使用第二个arg：builder('foo', {})调用它，或者为参数提供默认值：

export default function builder(path: string, {returnType = 'object'}: BuilderOptionsType = {}): BuilderReturnType { ... }

jest不了解流类型和对象解构吗？

1 个答案: