KPC
Kevin Powell - Community•2y ago
JWode

Proxyquire with a nested dependency

So I've got a test file and 2 modules. moduleA has a dependency, moduleB 
// moduleA.js
const ModuleB = require('./moduleB');

function functionA() {
  return 20 + ModuleB.functionB();
};

module.exports = { functionA };


// moduleB.js
const functionB = () => {
  return 10;
}

module.exports = { functionB } 
// moduleA.js
const ModuleB = require('./moduleB');

function functionA() {
  return 20 + ModuleB.functionB();
};

module.exports = { functionA };


// moduleB.js
const functionB = () => {
  return 10;
}

module.exports = { functionB }
My test file stubs out functionB (returned from moduleB) using proxyquire: 
const sinon = require('sinon');
const proxyquire = require('proxyquire');

describe('Unit Tests', function() {
  it('should work', () => {
    const mockedFn = sinon.stub();
    mockedFn.returns(30);

    const copyModuleA = proxyquire('./moduleA', {
      './moduleB': {
        functionB: mockedFn
      }
    });

    console.log(copyModuleA.functionA());
  })
});
const sinon = require('sinon');
const proxyquire = require('proxyquire');

describe('Unit Tests', function() {
  it('should work', () => {
    const mockedFn = sinon.stub();
    mockedFn.returns(30);

    const copyModuleA = proxyquire('./moduleA', {
      './moduleB': {
        functionB: mockedFn
      }
    });

    console.log(copyModuleA.functionA());
  })
});
So it outputs 50 (stubbed functionB 30 + functionA 20) Now I'm trying to take this example into my code: moduleA in this case is a file called validation.js. It is dependent on moduleB, in this case a sequelize model, Person. validation.js exports module.exports = { validateLogin };, a function that calls validate, which returns a function that uses Person.findOne() So in my mind, as with the simple example, I need to create a stub, point to the validation module in proxyquire, and reference the dependency and its findOne function. Like this:
1 Reply
JWode
JWodeOP•2y ago
const stubbedFindOne = sinon.stub();
stubbedFindOne.resolves();
validationModule = proxyquire('../../utils/validation', {
  '../models/Person': {
    findOne: stubbedFindOne
  }
});
const stubbedFindOne = sinon.stub();
stubbedFindOne.resolves();
validationModule = proxyquire('../../utils/validation', {
  '../models/Person': {
    findOne: stubbedFindOne
  }
});
This should stub Person.findOne in validation.js. But it doesn't seem to. And I have no idea why. 
let validationModule;

describe('Unit Tests', () => {
  before(() => {
    const stubbedFindOne = sinon.stub();
    stubbedFindOne.resolves();
    validationModule = proxyquire('../../utils/validation', {
      '../models/Person': {
        findOne: stubbedFindOne
      }
    });

  }) 
  it.only('should return 422 if custom email validation fails', async() => {

    const wrongEmailReq = { body: {email: '[email protected]'} };

    const res = {
      statusCode: 500,
      status: (code) => {this.statusCode = code; return this},
    };
  
    const validationFn = validationModule.validateLogin();
    const wrongEmail = await validationFn(wrongEmailReq, res, ()=>{});

    expect(wrongEmail.errors[0].msg).to.be.equal('Custom Authorisation Error');

    return;
  })
let validationModule;

describe('Unit Tests', () => {
  before(() => {
    const stubbedFindOne = sinon.stub();
    stubbedFindOne.resolves();
    validationModule = proxyquire('../../utils/validation', {
      '../models/Person': {
        findOne: stubbedFindOne
      }
    });

  }) 
  it.only('should return 422 if custom email validation fails', async() => {

    const wrongEmailReq = { body: {email: '[email protected]'} };

    const res = {
      statusCode: 500,
      status: (code) => {this.statusCode = code; return this},
    };
  
    const validationFn = validationModule.validateLogin();
    const wrongEmail = await validationFn(wrongEmailReq, res, ()=>{});

    expect(wrongEmail.errors[0].msg).to.be.equal('Custom Authorisation Error');

    return;
  })
And this is my validation.js file: 
const Person = require('../models/Person');

// parallel processing
const validate = validations => {
  return async (req, res, next) => {
    await Promise.all(validations.map(validation => validation.run(req)));

    const errors = validationResult(req);
    if (errors.isEmpty()) {
      return next();
    }

    const error = new Error();
    error.message = process.env.NODE_ENV === 'development'? 'Validation Failed':'Error';

    error.statusCode = !errors.isEmpty()? 422:500;
    error.errors = errors.array({onlyFirstError: true});
    next(error);
    return error;
  };
};

const validateLogin = () => {
  const validations = [
    body('email')
    .isString()
    // snip
    .custom(async (value, {req}) => {
        try{
            const person = await Person.findOne({ where: { email: value } });
            
            if(!person) return Promise.reject('Custom Authorisation Error'); 

        } catch(err) {
          throw err;
        }
    })
    .trim(),
  ];

  return validate(validations);
}

module.exports = {
  validateLogin
};
const Person = require('../models/Person');

// parallel processing
const validate = validations => {
  return async (req, res, next) => {
    await Promise.all(validations.map(validation => validation.run(req)));

    const errors = validationResult(req);
    if (errors.isEmpty()) {
      return next();
    }

    const error = new Error();
    error.message = process.env.NODE_ENV === 'development'? 'Validation Failed':'Error';

    error.statusCode = !errors.isEmpty()? 422:500;
    error.errors = errors.array({onlyFirstError: true});
    next(error);
    return error;
  };
};

const validateLogin = () => {
  const validations = [
    body('email')
    .isString()
    // snip
    .custom(async (value, {req}) => {
        try{
            const person = await Person.findOne({ where: { email: value } });
            
            if(!person) return Promise.reject('Custom Authorisation Error'); 

        } catch(err) {
          throw err;
        }
    })
    .trim(),
  ];

  return validate(validations);
}

module.exports = {
  validateLogin
};
-------------------------------------------------- Answer So this: 
const stubbedFindOne = sinon.stub();
stubbedFindOne.resolves();
validationModule = proxyquire('../../utils/validation', {
  '../models/Person': {
    findOne: stubbedFindOne
  }
});
const stubbedFindOne = sinon.stub();
stubbedFindOne.resolves();
validationModule = proxyquire('../../utils/validation', {
  '../models/Person': {
    findOne: stubbedFindOne
  }
});
Is basically the correct code to stub the nested dependency as far as i can see now (it's working, i'm never touching the code again) My idiocy was here: stubbedFindOne.resolves(); (or rejects()) both failed for me 
try{      
    const person = await Person.findOne({ where: { email: value } });
            
    if(!person) return Promise.reject('Custom Authorisation Error'); 

  } catch(err) {
      throw err;
  }
try{      
    const person = await Person.findOne({ where: { email: value } });
            
    if(!person) return Promise.reject('Custom Authorisation Error'); 

  } catch(err) {
      throw err;
  }
stubbedFindOne.return(null) was the winner. If you look at the above code, I shouldn't be rejecting a promise - the sequelize method doesn't do that, it returns null resolves() was just straight up wrong and I think I was blindly changing code to try and get any different result. rejects() doesn't work because it jumps to the catch block.

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