运行单元测试时如何抑制来自 node.js 应用程序的应用程序日志消息？
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How to suppress application logging messages from a node.js application when running unit tests?
提问by andimeier
While unit-testing my node.js application (which is basically a REST backend) using mocha and supertest, I need only the test-specific message on the screen, but the stdout is also cluttered with application log messages.
在使用 mocha 和 supertest 对我的 node.js 应用程序（基本上是 REST 后端）进行单元测试时，我只需要屏幕上的特定于测试的消息，但标准输出也充斥着应用程序日志消息。
I start the unit test with:
我开始单元测试：
mocha -R spec .
... and get this output (this is what it should notbe):
...并获得此输出（这是不应该的）：
[App] Listening on port 3000 ...
[App] Starting app, hooray!
Project API
GET /projects
[App] entering "projects" module ...
√ should return an array of projects (317ms)
I marked the application log message with [App]. What I really wantwould be this output from the unit test:
我用 [App] 标记了应用程序日志消息。我真正想要的是单元测试的输出：
Project API
GET /projects
√ should return an array of projects (317ms)
How can I suppress console.log/warn/error output by the application interspersed with Mocha's reporter output?
如何抑制应用程序的 console.log/warn/error 输出，其中穿插着 Mocha 的报告器输出？
SOLUTION:
解决方案：
Following dankohn's approach, I ended up like this, which solves my issue (using winstonfor logging):
按照 dankohn 的方法，我最终得到了这样的结果，这解决了我的问题（使用winston进行日志记录）：
(in node's "main" server file, server.js:)
（在节点的“主”服务器文件 server.js 中：）
if (process.env.NODE_ENV !== 'test') {
logger = new (winston.Logger)({
transports: [
new (winston.transports.Console)(),
new (winston.transports.File)({ filename: 'foo.log' })
]
});
} else {
// while testing, log only to file, leaving stdout free for unit test status messages
logger = new (winston.Logger)({
transports: [
new (winston.transports.File)({ filename: 'foo.log' })
]
});
}
... and to set the env variable, each unit test file starts with:
...并设置 env 变量，每个单元测试文件都以：
process.env.NODE_ENV = 'test';
采纳答案by Dan Kohn
In your app.js:
在你的 app.js 中：
if (process.env.NODE_ENV !== 'test') {
app.use(express.logger());
}
At the top of each of your mocha files:
在每个 mocha 文件的顶部：
process.env.NODE_ENV = 'test';
Update:
更新：
We use this function in our import code:
我们在导入代码中使用这个函数：
function logExceptOnTest(string) {
if (process.env.NODE_ENV !== 'test') {
console.log(string);
}
}
Then, replace all your console.log('it worked')with logExceptOnTest('it worked'). The basic trick is to use environment variables as a global flag as to the level of logging you want.
然后，console.log('it worked')用logExceptOnTest('it worked'). 基本技巧是使用环境变量作为您想要的日志记录级别的全局标志。
回答by Derek Soike
Here's a pretty simple solution that uses SinonJS's test stubsto suppress all console.log/info/warn/errorstatements before running your tests.
这是一个非常简单的解决方案，它使用SinonJS的测试存根console.log/info/warn/error在运行测试之前抑制所有语句。
// my-method.js
export function myMethod() {
console.log(`I'm about to return true`)
return true
}
// my-method.test.js
import {describe, it, before} from 'mocha'
import chai from 'chai'
import sinon from 'sinon'
import chalk from 'chalk'
import {myMethod} from './my-method.js'
const expect = chai.expect
describe(chalk.underline('My Test Group'), () => {
before(() => {
sinon.stub(console, 'log') // disable console.log
sinon.stub(console, 'info') // disable console.info
sinon.stub(console, 'warn') // disable console.warn
sinon.stub(console, 'error') // disable console.error
})
describe('myMethod', () => {
it('should return true', () => {
expect(myMethod()).to.be.true // without printing to the console
})
})
})
// output
My Test Group
myMethod
? should return true
回答by Justin Hamade
Already answered but thought I would add that you can do this user winston.add()
已经回答但我想我会补充说你可以做这个用户 winston.add()
var logger = new (winston.Logger)({
transports: [
new (winston.transports.File)({filename: 'node.log'})
]
});
if (process.env.NODE_ENV === 'test') {
logger.add(winston.transports.Console, {prettyPrint: true});
}