A suite is a set of test cases that you want to test for a JavaScript object or function. You can think of a suite as being similar to a test class in Apex, if you want to make a comparison.
A suite uses a global describe function, and the function has two parameters: a string that is the title of the test suite and a function that implements the test suite.
The syntax is as follows:
//This is Test Suitedescribe("Test Lightning Components", function() { //.....});
Let's say we have a library that has a string of util functions, which takes a string and performs camelcasing, concatenation, and so on. The following suite definition code snippet can be used to test this JavaScript file:
//This is test Suitedescribe("StringUtils", function() ...