Support construction of `Record`s and `Metadata`

[alexcrichton]

Testing and "shim loggers" typically want to do this so we should support these constructions! We probably want to have the construction go through builders to ensure that we can flexibly add more fields in the future.

I'm not tagging this issue as "easy" just yet as it's got some API design involved, but if we get a concrete design listed here I think it'd be great to tag this issue as "easy" afterwards for an implementation to come by.

[rap2hpoutre]

@alexcrichton Since LogRecord and LogMetadata were renamed, could you edit the title and replace:

'Support construction of LogRecords and LogMetadata

By:

Support construction of Record and Metadata

It's not really important, but I think it may confuse users (including me!).

[sfackler]

Fixed!

[omh1280]

I'll begin working on this!

• Create RecordBuilder and MetadataBuilder structs
• impl the following setters for MetadataBuilder:
  • level() and target()
• impl the following setters for RecordBuilder:
  • args(), metadata(), location()
• impl a build() method for each Builder and returns a Record or a Metadata
• Update the docs to specify that the use of these builders is for testing and "shim loggers"

Look ok?

[brson]

@omh1280 that looks reasonable to me. Methods should probably take &mut self.

[omh1280]

I'm not sure how to give an example for creating a Location. It's accessible (pub), but it's hidden from the docs and I think giving an example using it would be a bad decision. It's also a necessary part of constructing a full Record.

Does Location need a builder, too?

[sfackler]

Yep

[omh1280]

I've submitted a PR for this!

[brson]

Thanks @omh1280! Sorry for the delay 👍