英文:
nodejs Jest testing exec.stdout.on('data',data)
问题
尝试测试一个包含child_process库exec的函数。
const { exec } = require('child_process')
const randomFunc = () => {
const newSync = exec('要执行的一些命令')
newSync.stdout.on('data', data => {
console.log(data.toString())
})
}
testfile:
const {randomFunc} = require(randomFuncFile)
const { exec } = require('child_process')
jest.mock('child_process')
it('测试', () => {
const readStreamObject = {
on: jest.fn().mockImplementation(function (event, handler) {
handler('streaming ')
})
}
exec.mockImplementation(data => ({stdout: readStreamObject}))
randomFunc()
expect(exec.stdout.on).toHaveBeenCalled()
}
我得到以下错误：
TypeError: Cannot read properties of undefined (reading 'on')
一些提示会很有帮助。
英文:
Trying to to test a function the incorporates the exec of child_process library.
const { exec } = require('child_process')
const randomFunc = () => {
const newSync = exec('some command to execute')
newSync.stdout.on('data', data => {
console.log(data.toString())
})
}
testfile:
const {randomFunc} = require(randomFuncFile)
const { exec } = require('child_process')
jest.mock('child_process')
it('test', () => {
const readStreamObject = {
on: jest.fn().mockImplementation(function (event, handler) {
handler('streaming ')
})
}
exec.mockImplementation(data => ({stdout: readStreamObject})
randomFunc()
expect(exec.stdout.on).toHaveBeenCalled()
}
I'm getting
> TypeError: Cannot read properties of undefined (reading 'on')
some tips would be great.
答案1
得分: 1
你可以通过模拟的exec()函数获取模拟执行的stdout，方法是使用exec.mock.results[0].value.stdout，详见这里。
index.js：
const { exec } = require('child_process');
const randomFunc = () => {
const newSync = exec('要执行的某个命令');
newSync.stdout.on('data', (data) => {
console.log(data.toString());
});
};
module.exports = { randomFunc };
index.test.js：
const { exec } = require('child_process');
const { randomFunc } = require('./');
jest.mock('child_process');
it('测试', () => {
const mStdout = {
on: jest.fn().mockImplementation(function (event, handler) {
handler('流数据');
}),
};
exec.mockImplementation(() => ({ stdout: mStdout }));
randomFunc();
// expect(mStdout.on).toHaveBeenCalled();
// 或者
expect(exec.mock.results[0].value.stdout.on).toHaveBeenCalled();
});
测试结果：
PASS stackoverflow/75036469/index.test.js (8.403 s)
✓ test (15 ms)
console.log
流数据
at stackoverflow/75036469/index.js:6:13
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
index.js | 100 | 100 | 100 | 100 |
----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 9.016 s
英文:
You can get the mock stdout returned by mocked exec() function via exec.mock.results[0].value.stdout, See mockFn.mock.results
index.js:
const { exec } = require('child_process');
const randomFunc = () => {
const newSync = exec('some command to execute');
newSync.stdout.on('data', (data) => {
console.log(data.toString());
});
};
module.exports = { randomFunc };
index.test.js:
const { exec } = require('child_process');
const { randomFunc } = require('./');
jest.mock('child_process');
it('test', () => {
const mStdout = {
on: jest.fn().mockImplementation(function (event, handler) {
handler('streaming');
}),
};
exec.mockImplementation(() => ({ stdout: mStdout }));
randomFunc();
// expect(mStdout.on).toHaveBeenCalled();
// or
expect(exec.mock.results[0].value.stdout.on).toHaveBeenCalled();
});
Test result:
PASS stackoverflow/75036469/index.test.js (8.403 s)
✓ test (15 ms)
console.log
streaming
at stackoverflow/75036469/index.js:6:13
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
index.js | 100 | 100 | 100 | 100 |
----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 9.016 s
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