I am writing some unit tests for a codebase which uses octal literals. Whenever the test is executed with npm test
, a syntax error appears as follows:
Legacy octal literals are not allowed in strict mode.
I should stress that "use strict"
does not appear anywhere in the source code, nor can I identify any option in package-lock.json
or package.json
indicating strict mode. Both JSON files were created with the npm init -y
and received no further modification except the addition of:
"scripts": {
"test": "jest"
},
How can I force Jest out of strict mode in order to test code with legacy octal literals?
CodePudding user response:
Per the docs:
By default, Jest will use
babel-jest
transformer
You can explicitly tell Jest you don't want it to try to apply any transforms by setting the following Jest configuration (e.g. in jest.config.<ext>
or under $.jest
in the package file):
"transform": {}
See full example below. Alternatively, you can leave Babel's transforms active but configure it with "sourceType": "script"
.
package.json
:{ "name": "strict-jest", "version": "0.1.0", "description": "", "main": "index.js", "scripts": { "test": "jest" }, "keywords": [], "author": "", "license": "ISC", "devDependencies": { "jest": "^28.1.2" }, "jest": { "transform": {} } }
index.test.js
:it("works", () => { expect(0100).toEqual(64); });
Output:
$ npm t > [email protected] test > jest PASS ./index.test.js ✓ works (2 ms) Test Suites: 1 passed, 1 total Tests: 1 passed, 1 total Snapshots: 0 total Time: 0.257 s Ran all test suites.