Jasmine JavaScript Testing Framework Jasmine Custom Matchers and Extensions 2

Question 1

In the custom matcher compare function signature compare(actual, expected), what does 'actual' represent?

Accepted Answer

The value passed to expect()

Answer

The 'actual' parameter in the compare function receives whatever value was passed into expect(), while 'expected' receives arguments from the matcher call itself.

Question 2

How does Jasmine use a custom matcher's negated failure message when .not is used?

Accepted Answer

It calls negativeCompare if defined, otherwise it uses the default pass negation with the same message

Answer

If a negativeCompare function is provided in the matcher object, Jasmine uses it for .not expectations; otherwise it inverts the pass result but uses the existing message.

Question 3

What does jasmine.any(Constructor) match?

Accepted Answer

Any value that is an instance of the given Constructor or primitive type

Answer

jasmine.any() checks that the actual value is an instance of the provided constructor or, for primitives like Number/String, that typeof matches.

Question 4

What is jasmine.anything() used for in expectations?

Accepted Answer

Matches any value except null and undefined

Answer

jasmine.anything() is an asymmetric matcher that passes for any value that is not null or undefined, useful when you only want to confirm a value is present.

Question 5

Which custom matcher utility parameter gives access to equality testers when implementing deep equality in a custom matcher?

Accepted Answer

util (the jasmine utility object with matchersUtil.equals)

Answer

The factory function receives util as its first parameter, which provides matchersUtil.equals() for performing Jasmine-aware deep equality checks inside a custom matcher.

Jasmine JavaScript Testing Framework Practice Test

Jasmine JavaScript Testing Framework Practice Test

Jasmine JavaScript Testing Framework Jasmine Custom Matchers and Extensions 2