Find and use full path to percy-healthcheck script (#67)

* Find and use full path to percy-healthcheck script.

* Make directory creation Node-8-compatible.

lib/index.ts

@@ -1,5 +1,6 @@
 import {clientInfo, environmentInfo} from './environment'
 import PercyAgent from '@percy/agent'
+import * as path from 'path'
 
 declare const Cypress: any
 declare const cy: any
@@ -10,13 +11,12 @@ Cypress.Commands.add('percySnapshot', (name: string, options: any = {}) => {
   // Use cy.exec(...) to check if percy agent is running. Ideally this would be
   // done using something like cy.request(...), but that's not currently possible,
   // for details, see: https://github.com/cypress-io/cypress/issues/3161
-  // We rely on node finding the percy-healtcheck binary and running it correctly,
-  // which is more cross-platform friendly than running the script directly ourselves.
-  const healthcheck = `node percy-healthcheck ${percyAgentClient.port}`
+  const healthcheck = `node ${_healthcheckPath()} ${percyAgentClient.port}`
   cy.exec(healthcheck, {failOnNonZeroExit: false}).then((result: any) => {
     if (result.code != 0) {
       // Percy server not available, or we failed to find the healthcheck.
       cy.log('[percy] Percy agent is not running. Skipping snapshots')
+      cy.log(`[percy] Healthcheck output: ${result.stdout}\n${result.stderr}`)
       return
     }
 
@@ -42,3 +42,24 @@ Cypress.Commands.add('percySnapshot', (name: string, options: any = {}) => {
     })
   })
 })
+
+
+// An attempt to resiliently find the path to the 'percy-healthcheck' script, and to do so
+// in a cross-platform manner.
+function _healthcheckPath() {
+  try {
+    // Try to resolve with respect to the install local module.
+    return require.resolve('@percy/cypress/dist/percy-healthcheck')
+  } catch {
+    try {
+      // Try to resolve relative to the current file.
+      return require.resolve('./percy-healthcheck')
+    } catch {
+      // Oh well. Assume it's in the local node_modules.
+      // It would be nice to use __dirname here, but this code is entirely executed inside of
+      // Cypress' unusual context, making __dirname always '/dist' for this file, which is
+      // unhelpful when trying to find a working filesystem path to percy-healthcheck.
+      return path.join('.', './node_modules/@percy/cypress/dist/percy-healthcheck')
+    }
+  }
+}

percy-healthcheck → lib/percy-healthcheck

@@ -13,7 +13,10 @@ const healtcheck = options => {
     const request = http.request(options, res => {
       resolve(res.statusCode === 200)
     })
-    request.on('error', err => reject(err))
+    request.on('error', (err) => {
+      console.log(`Healthcheck failed: ${err}`)
+      reject(err)
+    })
     request.end()
   })
 }

package.json

@@ -4,15 +4,12 @@
   "description": "Cypress client library for visual regression testing with Percy (https://percy.io).",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
-  "bin": {
-    "percy-healthcheck": "percy-healthcheck"
-  },
   "scripts": {
     "pretest": "npm run build",
     "test": "percy exec -- node run-tests.js",
     "test:debug": "LOG_LEVEL=debug npm run test",
     "clean": "rm -rf dist/",
-    "build": "npm run clean && tsc",
+    "build": "npm run clean && tsc && cp lib/percy-healthcheck dist/percy-healthcheck",
     "prepublish": "npm run build",
     "lint": "tslint -p . -t stylish --fix",
     "cypress:open": "cypress open"

run-tests.js

@@ -4,13 +4,24 @@ const port = process.env.PORT_NUMBER || 8000;
 const spawn = require('child_process').spawn;
 const platform = require('os').platform();
 
-// Copy our healthcheck binary to the 'node_modules/.bin' directory where it will be
+// Helper to make sure directories we need exist.
+function ensureDirExists(dir) {
+  if (! fs.existsSync(dir)) {
+    fs.mkdirSync(dir)
+  }
+}
+
+// Copy our healthcheck script to node_modules, where it will be
 // when this package is installed as a dependency.
-const src = 'percy-healthcheck'
+const src = 'lib/percy-healthcheck'
 const copyDst = /^win/.test(platform)
-      ? `${process.cwd()}\\node_modules\\.bin\\percy-healthcheck`
-      : `${__dirname}/node_modules/.bin/percy-healthcheck`;
+      ? `${process.cwd()}\\node_modules\\@percy\\cypress\\dist\\percy-healthcheck`
+      : `${__dirname}/node_modules/@percy/cypress/dist/percy-healthcheck`;
 console.log(`[run-tests] Copying ${src} to ${copyDst}`);
+// The 'recursive' fs.mkdirSync() option is only available in Node >10.12.0;
+// create all directories ourselves to accommodate Node 8.
+ensureDirExists('./node_modules/@percy/cypress')
+ensureDirExists('./node_modules/@percy/cypress/dist')
 fs.copyFileSync(src, copyDst);
 
 // We need to change the command path based on the platform they're using