Use Case

As a... BSON user / shell user
I want... Binary types to be created in the form they will be serialized in
So that... inspecting them and performing transformations on them do not work with unexpected values

User Experience

• It is desirable that the in memory representation of the Binary object match how it will be serialized as early as possible.
• Match how the Int32 class makes the number truncate to an int32 in the ctor like how it will eventually be truncated in the serializer.
• It sort of leads to bugs:

var uuid = new UUID();
var b = Binary.createFromBase64(u.toString('base64'), '4'); // stringified sub_type!
// ...
b.toUUID();
BSONError: Binary sub_type "4" is not supported for converting to UUID. Only "4" is currently supported. // hard to tell what this is pointing out
// ...
BSON.deserialize(BSON.serialize({ b })) // round trips perfectly fine
{ b: new UUID('1e54853f-d91f-41c7-9f98-f4e6faeec2da') }

Dependencies

• None

Risks/Unknowns

• None

Acceptance Criteria

Implementation Requirements

• In the Binary constructor, match the serializer behavior and cast the subType input to a Number
• Improve the toUUID() error message to make the type information of the subType clear

Testing Requirements

• Regression test for the number casting behavior
• Check for the new improved error message

Documentation Requirements

• TBD? The typescript already claims the property to be a number, the fact that it can be something else seems like we're fixing reality to match the existing docs?

Follow Up Requirements

• Are there other error messages where we stringify the input losing information in the process? (like how the string "4" became indistinguishable from the number "4")