Add facility to recognize specific error messages.

[EliRibble]

Also add the invalid user name and password message. This list should eventually grow as more errors are recognized. It prevents a client from having to either bubble up literally any text from RouterOS or have to rebuild all the different error strings themselves.

[archaron]

Great idea! Maybe we can avoid usage of map and can create errors directly inline?

const (
  ErrInvalidUserNameOrPassword = decodedDeviceError("invalid user name or password (6)")
  ErrConnection                = decodedDeviceError("... cannot connect ...")
)

type decodedDeviceError string
func (e decodedDeviceError) Error() string { return string(e) }

And then, instead of:

case trapSentence, fatalSentence:
		return sen.Word == fatalSentence, DeviceErrorFromSentence(sen)

we can create errors like this:

case trapSentence, fatalSentence:
  if msg, ok := sen.Map["message"]; ok {
   // custom error found
   return sen.Word == fatalSentence, processedDeviceError(msg)
  }

  return sen.Word == fatalSentence, &DeviceError{Sentence: sen}

So, we can do in client code:

if errors.Is(err, routeros.ErrInvalidUserNameOrPassword)  {
  // Auth error
}

Just as an idea.

BTW: Need to investigate, can error be like 'unable to connect to 192.168.0.1' ? If yes, this code will not work properly and we need some other solution to handle such errors.

Also, we need tests for this.

[EliRibble]

Good ideas, next time I work on this project I'll try adding them and report back.

[EliRibble]

In your example, what is processedDeviceError doing? I didn't find a function with that name in the repo. Is it just a rename of my DeviceErrorFromSentence? If so, wouldn't we still need the map?

[archaron]

Yep! It's my fault, of course it must be like:

return sen.Word == fatalSentence, decodedDeviceError(msg)

Just creates a new error based on sentece message.

As i can see, these errors needed for tests to pass:

const (
	ErrInvalidUserNameOrPassword = decodedDeviceError("invalid user name or password (6)")
	ErrIncorrectLogin            = decodedDeviceError("incorrect login")
	ErrAlreadyExists             = decodedDeviceError("failure: entry already exists")
)

And of course, we need to replace error check in test code from:

        var devErr *DeviceError
	require.Truef(t, errors.As(err, &devErr), "wait for device error: %v", err)
	require.Contains(t, []string{"cannot log in", "invalid user name or password (6)"}, devErr.fetchMessage())

to something like this:

      require.Equal(t, ErrInvalidUserNameOrPassword, err)

[EliRibble]

Thanks, I've updated the PR, including the tests. I had to make some adjustments to make it so other tests continue to pass, specifically proto_test.TestRunTrap which expects a DeviceError. Instead of just returning a decodedDeviceError I return a DeviceError-wrapped decodedDeviceError.