Add missing test file

Author: octet-stream

src/public/NoIdFieldError.test.ts

@@ -0,0 +1,10 @@
+import test from "ava"
+
+import {NoIdFieldError} from "./NoIdFieldError.js"
+
+test("Has valid properties", t => {
+  const actual = new NoIdFieldError()
+
+  t.is(actual.message, "Node must have an ID field.")
+  t.is(actual.code, "SLATE_TO_REACT_NO_ID_FIELD_ERROR")
+})