Question

In a ViewModel I have a few properties which have required and regular expression validations (on the same property) as follows:

// ...other properties...
MaxDays: ko.observable("").extend({
    required: { message: "You have to specify the maximum number of days." },
    pattern: {
        message: "Please enter a valid number.",
        params: '[0-9]+$',
        maxLength: 10
    }
}),
// ...other properties...

I’m using Jasmine to test and I noticed that if I assign a value that doesn’t match the expression, the value is ignored and it runs its own test for "required" as if there’s no data in that property.

// ... describe, other "it" statements, etc...
it("should complain if there's incorrect data", function () {

    viewModel.MaxDays("Zweiundzwanzig");

    expect(viewModel.errors().length).toBeGreaterThan(0);
    expect(viewModel.errors()).toContain('Please enter a valid number.');

    console.log(viewModel.errors());

});
// ...

When I run the test it fails. the errors collection is filled with an error but not because I entered a string when it should be a number. It fails because it thinks that property is empty. I get the error message from "required" instead of the message from "pattern":

The funny part is that it works on the UI, so if I go on the field bound to that property and type a string value, it will fire the regex validation and put the correct error message beside the field.

Can anyone point out what I’m missing here?

Answer 1

knockout.validation.group.errors() does currently not update correctly if the error type changes (see https://github.com/ericmbarnard/Knockout-Validation/issues/218).

I assume that this is your problem. Try to set ‘MaxDays’ to a correct value and then to the invalid one. That should fix the test if that was your problem.