This CL implements validation for the "type", "enum" and "const"
keywords.
Validation in its full generality requires that references in the schema
be resolved. We put that off for now; it isn't needed for most simple
keywords.
The JSON Schema folks provide an extensive test suite for validation at
https://github.com/json-schema-org/JSON-Schema-Test-Suite. We use it for
our tests, copying the necessary files into testdata. The files aren't
perfectly independent; for example, one test in enum.json requires the
"properties" keyword, which we haven't done yet. We will excise those
tests via calls to t.Skip as they arise.
Change-Id: I568b5c87802a39aecbc58f342931308fc8fb211c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/667875
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>