jstest

Context blocks

jstest specs are arranged in nested context blocks, much like in RSpec, Jasmine and other frameworks. Contexts are delimited by describe blocks (you can use context instead of describe). Within each block you can have multiple before and after blocks, that describe what to do before and after each test. The tests themselves are added using the it or should function.

Properties assigned to the test during a before block are available in the it block, so you can use before to set up state for the test.

JS.Test.describe('Arrays', function() { with(this) {
  before(function() { with(this) {
    this.array = [1, 2, 3]
  }})

  it('has a length property', function() { with(this) {
    assertEqual( 3, array.length )
  }})
}})

Each test is run by performing the following tasks:

• The before blocks from all the enclosing contexts are run from outermost to innermost.
• If the before blocks did not raise any errors, the test itself is run.
• The after blocks from all the enclosing contexts are run in order, this time from innermost to outermost.

For example, take this set of tests:

JS.Test.describe('thing', function() { with(this) {
  before(function() { this.puts('outer before') })
  after (function() { this.puts('outer after') })

  it('has tests', function() { with(this) {
    puts('outer test')
  }})

  describe('nested', function() { with(this) {
    before(function() { this.puts('INNER before') })
    after (function() { this.puts('INNER after') })

    it('does something', function() { with(this) {
      puts('INNER test')
    }})
  }})
}})

This test suite produces this output:

outer before
outer test
outer after

outer before
INNER before
INNER test
INNER after
outer after

Your before and after blocks are run once for every it block in your tests. before blocks are typically used to create or modify the objects you want to test, and after blocks are used to reset any global state you may have changed during the tests, for example to clear out a database.