New Relic Test Utilities

Library full of test utilities and helpers for New Relic instrumentation modules. The full documentation for this module can be found on GitHub.

TestAgent Helper

The {@link TestAgent} class helps set up a New Relic agent suitable for tests. With this you can run your tests within transactions without having to actually set up a full New Relic application. The helper should be created and torn down for each test to ensure you are running in a clean environment each time. In tap this may look like this:

tap.test('some test suite', (t) => {
  var helper = null
  t.beforeEach((done) => {
    helper = utils.TestAgent.makeInstrumented()
    done()
  })

  t.afterEach((done) => {
    helper && helper.unload()
    done()
  })

  t.test('test 1', (t) => {
    helper.runInTransaction((tx) => {
      // Your test is now in transaction context and normal instrumentation
      // logic should occur.
    })
  })
})

Assertions

There are a number of assertions provided to help write your tests. Each of these assertions can either be used directly (utils.assert.segments(...)) or as tap tests (t.segments(...)). In the direct use case they will throw exceptions, and thus can be used like any other assertion library. Here are a few examples of using them:

var tap = require('tap')
var utils = require('@newrelic/test-utilities')

// This adds all the assertions to tap's `Test` class.
utils.assert.extendTap(tap)

tap.test((t) => {
  var helper = utils.TestAgent.makeInstrumented()
  t.tearDown(() => helper.unload())

  helper.runInTransaction((tx) => {
    // Do some testing logic...

    // This will check that transaction state hasn't been lost and that the given
    // transaction is the currently active one. A good check to make in the
    // callbacks to asynchronous methods.
    t.transaction(tx, 'should be in correct context')

    // This will check that the transaction trace has the segment structure you
    // describe. Extra segments in the trace are allowed.
    t.segments(tx.trace.root, [{name: 'mysegment'}], 'should have expected segments')

    // Like above, this checks the structure of the trace against the one you
    // describe but they must exactly match. Any extra segments in the trace are
    // considered a failure.
    t.exactSegments(tx.trace.root, [{name: 'mysegment'}], 'should have expected segments')

    // Many metrics are not created until the transaction ends, if you're
    // missing metrics in your instrumentation tests, this may help.
    tx.end()

    // This will check that the metrics given have been created. Extra metrics
    // are allowed.
    t.metrics(['/My/Metric'], 'should have created metrics')

    // Like above, this checks that the given metrics were created. Any extra
    // metrics that were created are considered a failure.
    t.exactMetrics(['/My/Metric', '/Another/Metric'], 'should have exactly these metrics')
  })
})