@apio/express-prometheus/lib/index.test.js

Express middleware to provide basic metrics to Prometheus.

const supertest = require('supertest')
const express = require('express')
const expressPrometheus = require('./index')

describe('index', () => {
  let sut

  describe('options', () => {
    beforeEach(() => {
      sut = express()
    })

    test('When not given url, should default to metrics', () => {
      // Arrange
      expressPrometheus.instrument(sut)
      // Act
      return supertest(sut)
        .get('/metrics')
        .then(result => {
          // Assert
          expect(result.statusCode).toBe(200)
        })
    })

    test('When given url, should default to url value', () => {
      // Arrange
      const options = {
        url: '/metric-route'
      }

      expressPrometheus.instrument(sut, options)

      // Act
      return supertest(sut)
        .get(options.url)
        .then(result => {
          // Assert
          expect(result.statusCode).toBe(200)
        })
    })
  })

  describe('metrics', () => {
    let agent

    beforeEach(() => {
      sut = express()
      expressPrometheus.instrument(sut)

      sut.get('/resource', (req, res) => {
        res.send()
      })

      sut.get('/resource/:id', (req, res) => {
        res.send()
      })

      agent = supertest.agent(sut)
    })

    describe('http_requests_processing', () => {
      test('Given metrics are running, should include http_requests_processing', () => {
        // Arrange
        // Act
        return agent.get('/resource').then(() => {
          return agent.get('/metrics').then(result => {
            expect(result.statusCode).toBe(200)
            expect(result.headers['content-type']).toBe(
              'text/plain; charset=utf-8'
            )
            expect(result.text).toContain('http_requests_processing 0')
          })
        })
      })
    })

    describe('http_requests_total', () => {
      test('Given resource has been request, should being included in http_requests_total', () => {
        // Arrange
        // Act
        return agent.get('/resource').then(() => {
          return agent.get('/metrics').then(result => {
            expect(result.statusCode).toBe(200)
            expect(result.headers['content-type']).toBe(
              'text/plain; charset=utf-8'
            )
            expect(result.text).toContain(
              'http_requests_total{method="GET",path="/resource",status="200"} 2'
            )
          })
        })
      })

      test('Given resource/:id has been request, should being included in http_requests_total', () => {
        // Arrange
        const id = 8

        // Act
        return agent.get(`/resource/${id}`).then(() => {
          return agent.get('/metrics').then(result => {
            expect(result.statusCode).toBe(200)
            expect(result.headers['content-type']).toBe(
              'text/plain; charset=utf-8'
            )
            expect(result.text).toContain(
              'http_requests_total{method="GET",path="/resource/:id",status="200"} 1'
            )
          })
        })
      })
    })

    describe('http_request_duration_seconds', () => {
      test('Given resource has been request, should being included in http_request_duration_seconds', () => {
        // Arrange
        // Act
        return agent.get('/resource').then(() => {
          return agent.get('/metrics').then(result => {
            expect(result.statusCode).toBe(200)
            expect(result.headers['content-type']).toBe(
              'text/plain; charset=utf-8'
            )
            expect(result.text).toContain(
              'http_request_duration_seconds_bucket{le="10",method="GET",path="/resource",status="200"} 3'
            )
          })
        })
      })

      test('Given resource/:id has been request, should being included in http_request_duration_seconds', () => {
        // Arrange
        const id = 3

        // Act
        return agent.get(`/resource/${id}`).then(() => {
          return agent.get('/metrics').then(result => {
            expect(result.statusCode).toBe(200)
            expect(result.headers['content-type']).toBe(
              'text/plain; charset=utf-8'
            )
            expect(result.text).toContain(
              'http_request_duration_seconds_bucket{le="10",method="GET",path="/resource/:id",status="200"} 2'
            )
          })
        })
      })
    })

    describe('third party metrics', () => {
      test('Given metrics running, should include default node metrics', () => {
        // Arrange
        // Act
        return agent.get('/metrics').then(result => {
          // Assert
          expect(result.text).toContain('nodejs_active_handles_total')
          expect(result.text).toContain('nodejs_active_requests_total')
          expect(result.text).toContain('nodejs_external_memory_bytes')
        })
      })
    })
  })

  describe('labels', () => {
    let agent

    beforeEach(() => {
      sut = express()
      expressPrometheus.instrument(sut)

      const router = express.Router()

      router.get('/', (req, res) => {
        res.send()
      })

      router.get('/:id', (req, res) => {
        res.send()
      })

      sut.use('/resource-1', router)
      sut.use('/resource-2', router)

      sut.get('/resource-3/', (req, res) => {
        res.send()
      })

      sut.get('/resource-3/:id', (req, res) => {
        res.send()
      })

      agent = supertest.agent(sut)
    })

    test('Given a router route is called, should calculate path correctly', () => {
      // Arrange
      // Act
      return agent.get('/resource-1/id-thing').then(() => {
        return agent.get('/metrics').then(result => {
          expect(result.statusCode).toBe(200)
          expect(result.headers['content-type']).toBe(
            'text/plain; charset=utf-8'
          )
          expect(result.text).toContain(
            'http_requests_total{method="GET",path="/resource-1/:id",status="200"} 1'
          )
        })
      })
    })

    test('Given a app route is called, should calculate path correctly', () => {
      // Arrange
      // Act
      return agent.get('/resource-3/id-thing-3').then(() => {
        return agent.get('/metrics').then(result => {
          expect(result.statusCode).toBe(200)
          expect(result.headers['content-type']).toBe(
            'text/plain; charset=utf-8'
          )
          expect(result.text).toContain(
            'http_requests_total{method="GET",path="/resource-3/:id",status="200"} 1'
          )
        })
      })
    })
  })
})