fix: improve error msg when bin is a directory (#3231)

lib/launchers/process.js

@@ -87,6 +87,9 @@ function ProcessLauncher (spawn, tempDir, timer, processKillTimeout) {
       if (err.code === 'ENOENT') {
         self._retryLimit = -1
         errorOutput = `Can not find the binary ${cmd}\n\tPlease set env variable ${self.ENV_CMD}`
+      } else if (err.code === 'EACCES') {
+        self._retryLimit = -1
+        errorOutput = `Permission denied accessing the binary ${cmd}\n\tMaybe it's a directory?`
       } else {
         errorOutput += err.toString()
       }

test/unit/launchers/process.spec.js

@@ -93,6 +93,26 @@ describe('launchers/process.js', () => {
         done()
       })
     })
+
+    it('should handle spawn EACCES error and not even retry', (done) => {
+      ProcessLauncher.call(launcher, mockSpawn, mockTempDir)
+      RetryLauncher.call(launcher, 2)
+      launcher._getCommand = () => BROWSER_PATH
+
+      const failureSpy = sinon.spy()
+      emitter.on('browser_process_failure', failureSpy)
+
+      launcher.start('http://host:9876/')
+      mockSpawn._processes[0].emit('error', {code: 'EACCES'})
+      mockSpawn._processes[0].emit('exit', 1)
+      mockTempDir.remove.callArg(1)
+
+      _.defer(() => {
+        expect(launcher.state).to.equal(launcher.STATE_FINISHED)
+        expect(failureSpy).to.have.been.called
+        done()
+      })
+    })
   })
 
   // higher level tests with Retry and CaptureTimeout launchers