Testing for undefined using the 'should' syntax in Chai

Question

Testing for undefined using the 'should' syntax in Chai

Inspired by this tutorial on testing an AngularJS app with Chai, I am trying to add a test for an undefined value using the "should" style. However, I encountered a failure when attempting this:

it ('cannot play outside the board', function() {
  scope.play(10).should.be.undefined;
});

The error message received was "TypeError: Cannot read property 'should' of undefined", but surprisingly, the test passed when using the "expect" style instead:

it ('cannot play outside the board', function() {
  chai.expect(scope.play(10)).to.be.undefined;
});

Can anyone advise on how to make it work with the "should" style?

javascript angularjs testing chai

Answer 1

Answer №1

One drawback of using the should syntax is that it relies on adding the should property to all objects, which can cause issues if a return value or variable value is undefined and there is no object to hold the property.

The documentation provides some solutions, such as:

var should = require('chai').should();
db.get(1234, function (err, doc) {
  should.not.exist(err);
  should.exist(doc);
  doc.should.be.an('object');
});

Answer 2

One drawback of using the should syntax is that it relies on adding the should property to all objects, which can cause issues if a return value or variable value is undefined and there is no object to hold the property.

The documentation provides some solutions, such as:

var should = require('chai').should();
db.get(1234, function (err, doc) {
  should.not.exist(err);
  should.exist(doc);
  doc.should.be.an('object');
});

Answer 3

Answer №2

assert.strictEqual(testedValue, undefined);

as stated in the chai documentation

Answer 4

assert.strictEqual(testedValue, undefined);

as stated in the chai documentation

Answer 5

Answer №3

(typeof scope.performAction(10)).should.equal('undefined');

Answer 6

(typeof scope.performAction(10)).should.equal('undefined');

Answer 7

Answer №4

Check for undefined value

const should = require('should');
...
should(scope.play(10)).be.undefined;

Verify if the value is null

const should = require('should');
...
should(scope.play(10)).be.null;

Determine if it is falsy, meaning treated as false in conditions

const should = require('should');
...
should(scope.play(10)).not.be.ok;

Answer 8

Check for undefined value

const should = require('should');
...
should(scope.play(10)).be.undefined;

Verify if the value is null

const should = require('should');
...
should(scope.play(10)).be.null;

Determine if it is falsy, meaning treated as false in conditions

const should = require('should');
...
should(scope.play(10)).not.be.ok;

Answer 9

Answer №5

Struggling with writing the should statement for undefined tests has been a challenge for me. The usual method doesn't seem to be effective.

target.should.be.undefined();

After some trial and error, I came up with alternative solutions.

(target === undefined).should.be.true()

Another approach is using a type check:

(typeof target).should.be.equal('undefined');

I'm not entirely certain if this is the correct way to handle it, but it seems to do the job.

I also found some insights on this issue in a post by ghost on GitHub

Answer 10

Struggling with writing the should statement for undefined tests has been a challenge for me. The usual method doesn't seem to be effective.

target.should.be.undefined();

After some trial and error, I came up with alternative solutions.

(target === undefined).should.be.true()

Another approach is using a type check:

(typeof target).should.be.equal('undefined');

I'm not entirely certain if this is the correct way to handle it, but it seems to do the job.

I also found some insights on this issue in a post by ghost on GitHub

Answer 11

Answer №6

Here's a suggestion:

it ('testing for out of bounds play', function() {
   expect(scope.play(10)).to.be.undefined; // should return undefined
   expect(scope.play(10)).to.not.be.undefined; // or not undefined
});

Answer 12

Here's a suggestion:

it ('testing for out of bounds play', function() {
   expect(scope.play(10)).to.be.undefined; // should return undefined
   expect(scope.play(10)).to.not.be.undefined; // or not undefined
});

Answer 13

Answer №7

Remember to utilize both the have and not keywords for an effective combination:

const mocha = require('mocha');
mocha.expect();
// ...
data.should.not.have.property('email');

Answer 14

Remember to utilize both the have and not keywords for an effective combination:

const mocha = require('mocha');
mocha.expect();
// ...
data.should.not.have.property('email');

Answer 15

Answer №8

After consulting the documentation, I found that @david-norman's answer was accurate. Although I encountered some setup issues, I ultimately decided to go with a different approach.

(typeof scope.play(10)).should.equal('undefined');

Answer 16

After consulting the documentation, I found that @david-norman's answer was accurate. Although I encountered some setup issues, I ultimately decided to go with a different approach.

(typeof scope.play(10)).should.equal('undefined');

Answer 17

Answer №9

To check if a function result is undefined, you can use the should() method along with testing for the type "undefined":

it ('verifies that playing outside the board returns undefined', function() {
  should(scope.play(10)).be.type('undefined');
});

Answer 18

To check if a function result is undefined, you can use the should() method along with testing for the type "undefined":

it ('verifies that playing outside the board returns undefined', function() {
  should(scope.play(10)).be.type('undefined');
});

Testing for undefined using the 'should' syntax in Chai

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

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