wanjikun / jest Goto Github PK

npm insatll --save-dev jest

1. expect().toBe()

• used with identical values

• Used along with matchers to assert something about a value

  Modifiers

  • .not - does the opposite
  • .resolves -
  • .toBeCloseTo - floating numbers

• Used to test values in different ways.
• Use describe to call a couple oftests together.

1. Common Matchers

• toBe() - uses Object.is to test exact equality
• toEqual() -checks the value of an object
  • ignores object keys with undefined properties, undefined array items, object type mismatch
• not -test for the opposite

2. Truthiness

• toBeNull matches only null
• toBeUndefined matches only undefined
• toBeDefined is the opposite of toBeUndefined
• toBeTruthy matches anything that an if statement treats as true
• toBeFalsy matches anything that an if statement treats as false

3. Numbers
4. Strings

• toMatch - used to check strings against regular expressions eg .toMatch(/stop/) -like includes

5. arrays and iterables

• toContain - check if an array or iterable contains a particular item

6. Exceptions