使用Chai JS进行自动化测试

Question

I want to load a configuration file for tests.

One of the parameters is type.

So how can I replace the next line.

expect(res.body).to.deep.equal(test.expect )

with "to.deep.equal" string.

I tried :

let exp = expect(res.body);
test.type.split('.').forEach(t => exp = exp[t])
exp(test.expect)

But then i got:

Uncaught TypeError: this.assert is not a function
  at assertEqual (node_modules\chai\lib\chai\core\assertions.js:1026:12)

EDIT:

I managed to do it in the following way:

let exp = expect(res.body);
test.type.split('.').slice(0,-1).forEach(t => exp = exp[t])
exp[_.last(test.type.split('.'))](test.expect)

I'd love to get an explanation for that. and if is exist another way for it.

Answer 1

Because you're breaking the thisValue of the last member ( equal ), which it tries to access but is no longer bound to deep object.

(I'm really butchering the explanation).

You can do:

let exp = expect(res.body);
test.type.split('.').forEach(t => {
    exp = typeof exp[t] === 'function'
        ? exp[t].bind(exp)
        : exp[t];
});
exp(test.expect)

To further explain, this is why you're seeing the TypeError: this.assert is not a function - the equal call is trying to access this.assert of the deep object, but the this is no longer bound to it. By explicitly binding it via .bind() we can retain it.

That's also why your second code example works, because you're properly calling the equal() as a method of deep .