to have length

Asserts that an array (or array-like object) has the specified length.

expect([1, 2, 3], 'to have length', 3);

In case of a failing expectation you get the following output:

expect([1, 2, 3], 'to have length', 4);

expected [ 1, 2, 3 ] to have length 4
  expected 3 to be 4

This assertion can be negated using the not flag:

expect([1, 2, 3], 'not to have length', 4);

In case of a failing expectation you get the following output:

expect([1, 2, 3], 'not to have length', 3);

expected [ 1, 2, 3 ] not to have length 3