encapsulated-error-handler.test.js — fastify Source File

Source Code

'use strict'

const { test } = require('node:test')
const Fastify = require('..')

// Because of how error handlers wrap things, following the control flow can be tricky
// In this test file numbered comments indicate the order statements are expected to execute

test('encapsulates an asynchronous error handler', async t => {
  t.plan(3)

  const fastify = Fastify()
  fastify.register(async function (fastify) {
    fastify.setErrorHandler(async function a (err) {
      // 3. the inner error handler catches the error, and throws a new error
      t.assert.strictEqual(err.message, 'from_endpoint')
      throw new Error('from_inner')
    })
    fastify.get('/encapsulated', async () => {
      // 2. the endpoint throws an error
      throw new Error('from_endpoint')
    })
  })

  fastify.setErrorHandler(async function b (err) {
    // 4. the outer error handler catches the error thrown by the inner error handler
    t.assert.strictEqual(err.message, 'from_inner')
    // 5. the outer error handler throws a new error
    throw new Error('from_outer')
  })

  // 1. the endpoint is called
  const res = await fastify.inject('/encapsulated')
  // 6. the default error handler returns the error from the outer error handler
  t.assert.strictEqual(res.json().message, 'from_outer')
})

// See discussion in https://github.com/fastify/fastify/pull/5222#discussion_r1432573655
test('encapsulates a synchronous error handler', async t => {
  t.plan(3)

  const fastify = Fastify()
  fastify.register(async function (fastify) {
    fastify.setErrorHandler(function a (err) {
      // 3. the inner error handler catches the error, and throws a new error
      t.assert.strictEqual(err.message, 'from_endpoint')
      throw new Error('from_inner')
    })
    fastify.get('/encapsulated', async () => {
      // 2. the endpoint throws an error
      throw new Error('from_endpoint')
    })
  })

  fastify.setErrorHandler(async function b (err) {
    // 4. the outer error handler catches the error thrown by the inner error handler
    t.assert.strictEqual(err.message, 'from_inner')
    // 5. the outer error handler throws a new error
    throw new Error('from_outer')
  })
// ... (178 more lines)