How does one properly to unit test Joi Schemas validation? - node.js

Question

I created a Joi validation schema that gets called in my routes. However when I run a code coverage that file is NOT being covered. So, I am trying to write a test for it.
Validator.js
const Joi = require('joi');
module.exports = {
validateExternalId: (schema, name) => {
return (req, res, next) => {
const result = Joi.validate({ param: req.params[name] }, schema);
if (result.error) {
return res.status(400).send(result.error.details[0].message);
}
next();
};
},
schemas: {
idSchema: Joi.object().keys({
param: Joi.string().regex(/^[a-zA-Z0-9]{20}$/).required()
})
}
};
Validator.test.js
const { validateExternalId, schemas } = require('../../src/helpers/validation');
const app = require('../../src/router')
const mockResponse = () => {
const res = {};
res.status = jest.fn().mockReturnValue(res);
res.json = jest.fn().mockReturnValue(res);
return res;
};
describe('Testing validateExternalId schema', () => {
it('It can validate the external Id Regex length', done => {
const req = {
params: [
{
extClientId: 'abcdefghij0123456789'
}
]
};
app.use('/token/:extClientId', validateExternalId(schemas.idSchema, 'extClientId');
// expect().toHaveBeenCalled();
});
});
Please Go Easy on ME... Here is my attempt on testing this Joi validator. I tried to but my expected wasn't working so I commented it out for now. any pointers would be appreciated. thank you

Answer 1

Here is the unit test solution:
validator.js:
const Joi = require('joi');
module.exports = {
validateExternalId: (schema, name) => {
return (req, res, next) => {
const result = Joi.validate({ param: req.params[name] }, schema);
if (result.error) {
return res.status(400).send(result.error.details[0].message);
}
next();
};
},
schemas: {
idSchema: Joi.object().keys({
param: Joi.string()
.regex(/^[a-zA-Z0-9]{20}$/)
.required(),
}),
},
};
validator.test.js:
const { validateExternalId, schemas } = require('./validator');
const Joi = require('joi');
describe('60730701', () => {
afterEach(() => {
jest.restoreAllMocks();
});
it('should send error', () => {
const validationResults = { error: { details: [{ message: 'validation error' }] } };
const validateSpy = jest.spyOn(Joi, 'validate').mockReturnValueOnce(validationResults);
const mReq = { params: { extClientId: '123' } };
const mRes = { status: jest.fn().mockReturnThis(), send: jest.fn() };
validateExternalId(schemas.idSchema, 'extClientId')(mReq, mRes);
expect(validateSpy).toBeCalledWith({ param: '123' }, schemas.idSchema);
expect(mRes.status).toBeCalledWith(400);
expect(mRes.send).toBeCalledWith('validation error');
});
it('should pass the validation and call api', () => {
const validationResults = { error: undefined };
const validateSpy = jest.spyOn(Joi, 'validate').mockReturnValueOnce(validationResults);
const mReq = { params: { extClientId: '123' } };
const mRes = {};
const mNext = jest.fn();
validateExternalId(schemas.idSchema, 'extClientId')(mReq, mRes, mNext);
expect(validateSpy).toBeCalledWith({ param: '123' }, schemas.idSchema);
expect(mNext).toBeCalled();
});
});
unit test results with 100% coverage:
PASS stackoverflow/60730701/validator.test.js (9.96s)
60730701
✓ should send error (6ms)
✓ should pass the validation and call api (2ms)
--------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
--------------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
validator.js | 100 | 100 | 100 | 100 |
--------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 2 passed, 2 total
Snapshots: 0 total
Time: 11.647s, estimated 15s
source code: https://github.com/mrdulin/react-apollo-graphql-starter-kit/tree/master/stackoverflow/60730701