Chai assertion, unable to identify property using should / expect - mocha.js

Question

Hello: Need your help on a chai assertion.
I have a JSON response as shown below. I want to assert that it contains "Lastname is mandatory" only.
I tried using this statement but the error i get is AssertionError: expected [ Array(2) ] to have a deep property '#text'. Please help how to write this correctly.
using expect
chai.expect(data.response.error).to.have.deep.property('#text', 'Lastname is mandatory.');
using should
data.response.error.should.have.deep.property('#text', 'Lastname is mandatory.');
Response JSON
{
response: {
error: [
{
'#id': '1000',
'#text': 'Firstname is mandatory.'
},
{
'#id': '10001',
'#text': 'Lastname is mandatory.'
}
],
result:
{
status: '0'
}
}
}

Answer 1

Prior to Chai version 4
The use of deep with property requires that you pass a complete path to the property you want to test. In other words, deep.property won't do a search through all the properties for you. As the documentation puts it:
If the deep flag is set, you can use dot- and bracket-notation for deep references into objects and arrays.
Something like:
data.response.should.have.deep.property("error[0].#text");
Or you can start the path to the property with an array index if the object on which you use should is an array:
data.response.error.should.have.deep.property("[0].#text");
Here is a complete example derived from the code you show:
const chai = require("chai");
chai.should();
const data = {
response: {
error: [
{
'#id': '1000',
'#text': 'Firstname is mandatory.'
},
{
'#id': '10001',
'#text': 'Lastname is mandatory.'
}
],
result:
{
status: '0'
}
}
};
it("works", () => {
data.response.should.have.deep.property("error[0].#text");
// Or this, which looks weird but is allowed...
data.response.error.should.have.deep.property("[0].#text");
});
Chai version 4 and later
The OP was using a release of Chai earlier than version 4. If you are using Chai version 4 and over, the flag to use to is not .deep anymore but .nested. So in earlier versions where you would use data.response.should.have.deep.property("error[0].#text"); in version 4 or later you'd use data.response.should.have.nested.property("error[0].#text");

Answer 2

Thanks to answer from #shvaikalesh at github. It has the relevant answer to my question which i provide here for future reference + the code extract is also below for quick reference.
chai.expect(data.response.error.some(e => e['#text'] == 'Lastname is mandatory.')).to.be.true