2 ways to print Jest console debug logs with examples

Sometimes, it is very difficult to debug test case execution for fixing failed test cases in JEST.

I faced console.log not working for printing debug logs. console.log outputs nothing during test case execution

Jest prints log using console.log statements

There are two options to enable logging

• using –silent

Jest by default suppresses the console log statements. It shows nothing instead of printing a log message.

JEST provides CLI option --silent=false to enable print log messages.

jest --silent=false

Other ways we can configure these options

• npm scripts jest command configured to run all test cases using the below scripts in package.json

{
    "scripts": {
        "test": "jest --config=jest.config.json"
        }
}

Next, You can run the below command to disable suppress logs. -- allows you to pass command line options to scripts tags

npm run test -- --silent=false

You can still configure the option directly in the scripts

{
    "scripts": {
        "test": "jest --silent --config=jest.config.json"
        }
}

• For local dependency without global installation, use the below command

./node_modules/.bin/jest --silent

For yarn users

yarn jest --silent true

For npx uses without installation

npx jest --silent true

• using the verbose mode option

Jest provides a –verbose CLI option to output the verbose of the log messages during execution.

To enable verbose using the command line

jest --verbose true

If you are using npm scripts, test configured as given below in package.json

{
    "scripts": {
        "test": "jest --silent"
        }
}

Next, You can run the below command

npm test -- --verbose=true

For local dependency without global installation, use the below command

./node_modules/.bin/jest --verbose true

For yarn users

yarn jest --verbose true

For npx uses without installation

npx jest --verbose true