BotFramework-Config Service Models Accept Any Type

[justinwilaby]

Given this example:

const blobService = new BlobStorageService():
Object.assign(blobService, {connectionString: 'some string', type: ServiceTypes.Dispatch}); // Should throw but doesn't since we are changing the type erroneously. 

assert(blobService instanceof BlobStorageService); // true

const surprise = BotConfigurationBase.serviceFromJSON(blobService);
assert(surprise instanceof BlobStorageService); // throws
assert(surprise instanceof DispatchService); // Oops! Changed the class type.
assert('connectionString' in surprise); // 'connectionString' is a property of BlobStorageService but somehow arrives in a DispatchService instance

The shape of service data models are not necessarily reliable and seemingly completely interchangeable which can lead to failures when using the instanceof operator or erroneously setting the wrong type on a "typed" data model instance.

One would expect the type field to be read-only and properties that do not belong to the data model to be omitted from the instance.

[tomlm]

This is by design.

The reason is that you have components that might not be in sync as to the objects which are stored in the .bot file. If you run a tool which is older you want to "round-trip" properties which aren't understood (because they are new), or types which aren't understood (because they are new).