tauri/cli/tauri.js/test/jest/__tests__/dev.spec.js

const path = require('path')
const fixtureSetup = require('../fixtures/app-test-setup')
const distDir = path.resolve(fixtureSetup.fixtureDir, 'app', 'dist')

function startDevServer() {
    const http = require('http')
    const { statSync, createReadStream } = require('fs')
    const app = http.createServer((req, res) => {
      if (req.method === 'GET') {
        if (req.url === '/') {
          const indexPath = path.join(distDir, 'index.html')
          const stat = statSync(indexPath)
          res.writeHead(200, {
            'Content-Type': 'text/html',
            'Content-Length': stat.size
          })
          createReadStream(indexPath).pipe(res)
        }
      }
    })

    const port = 7001

    const server = app.listen(port)
    return {
        server,
        url: `http://localhost:${port}`
    }
}

function runDevTest(tauriConfig) {
  fixtureSetup.initJest('app')
  const dev = require('api/dev')
  return new Promise(async (resolve, reject) => {
    try {
      const { promise, runner } = dev(tauriConfig)

      const isRunning = require('is-running')
      let success = false
      const checkIntervalId = setInterval(async () => {
        if (!isRunning(runner.pid) && !success) {
          const failedCommands = Object.keys(responses).filter(k => responses[k] === null).join(', ')
          server.close(() => reject("App didn't reply to " + failedCommands))
        }
      }, 2000)

      const { server, responses } = fixtureSetup.startServer(async () => {
        success = true
        clearInterval(checkIntervalId)
        // wait for the app process to be killed
        setTimeout(async () => {
          try {
            await runner.stop()
          } catch {}
          resolve()
        }, 2000)
      })
      await promise
    } catch (error) {
      reject(error)
    }
  })
}

describe('Tauri Dev', () => {
  const build = {
    distDir: distDir
  }

  const devServer = startDevServer()

  it.each`
    url
    ${devServer.url}
    ${distDir}
  `('works with dev pointing to $url', ({ url }) => {
    const runningDevServer = url.startsWith('http')
    const promise = runDevTest({
      build: {
        ...build,
        devPath: url
      },
      ctx: {
        debug: true,
        dev: true
      }
    })

    promise.then(() => {
      if (runningDevServer) {
        devServer.server.close()
      }
    })

    return promise
  })
})