Don't Crash on Map Update

[kyleVsteger]

Why am I opening this PR?

This PR addresses an issue with resolving "$ref". I'm not entirely sure how to reproduce to make a test case. It seems that in some cases, :__unresolved_refs gets deleted, or maybe not generated at all, for a given schema.

I was experiencing an issue in https://github.com/felt/felt/pull/12945 with $ref and made this change locally. The schema properly generates and validates with this change.

[doorgan]

I'd suggest creating modules in-place in the tests instead of helper modules, like here: https://github.com/felt/channel_spec/blob/main/test/channel_spec/socket_test.exs#L51-L69

[kyleVsteger]

👋 ! Any specific reason? I broke it out since it was 75+ lines of code and that seemed like a lot to put in a test

[doorgan]

I find it easier to have the whole setup in the test itself in macro heavy code to both have the full picture and making sure unrelated code is not affecting the generated code.
It's a matter of preference, but macros don't always produce helpful stacktraces so I'd rather avoid sharing modules in tests, and at least have the certainty that I know exactly which test is causing issues

[kyleVsteger]

That's true. However, the nested nature of the setup for this test doesn't allow us to make nested modules with refs. Example:

test "foo", %{mod: mod} do 
    # I can define the top level name
    defmodule :"#{mod}.LotsOfRefsSchema" do
      # And I can create modules in this namespace
      defmodule Base do
        def schema() do
          %{
            type: :object,
            properties: %{
              # But I can't reference it here — #{mod} is not available
              foo: %{"$ref": :"#{mod}.LotsOfRefsSchema.Foo"},
            },
            additionalProperties: false
          }
        end
      end

      defmodule Foo do
        def schema() do
          %{type: :object}
        end
      end
    end
end

[kyleVsteger]

error: undefined variable "mod"
  test/channel_spec/socket_test.exs:613: Test776.LotsOfRefsSchema.Base.schema/0
     ** (CompileError) test/channel_spec/socket_test.exs: cannot compile module Test776.LotsOfRefsSchema.Base (errors have been logged)

[doorgan]

Hmm that's a good point. You could move the defmodule Foo inside defmodule Base and use __MODULE__.Foo instead, or not nest them(you'd repeat .LotsofRefsSchema quite a bit) but it's a good point still.

I'm fine with either approach seeing a helper module may be easier

[kyleVsteger]

I just pushed a commit. I was able to get it to work with a @mod_base Module.split(__MODULE__) |> Enum.drop(-1) |> Module.concat()

[doorgan]

Oh nice trick! 💜

[doorgan]

The change fixes the issue and the new test extensively covers the ref resolution functionality

[axelson]

Thanks for adding the test! I have a small suggestion for cleaning up the module generation

[axelson]

Suggested change

	defmodule Base do
	@mod_base Module.split(__MODULE__) |> Enum.drop(-1) |> Module.concat()
	mod_base = __MODULE__
	defmodule Base do
	@mod_base mod_base

[kyleVsteger]

Nice — added in 3fe90cc