In Javascript:

function somefunction() { return true; }

Test.describe("This test", function() {
  Test.it("should return true", function() {
    Test.assertEquals(somefunction(), true);
  })
})

Result

This test:
  should return true:
    Test Passed: Value == true

Codewars should insert something like this as a default example for javascript :) In case you want more details, have a look at the javascript kata-test-framework repository on github