Add Automerge CRDT datatype helpers

test/crdt-automerge.test.ts

@@ -0,0 +1,47 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import * as Automerge from "@automerge/automerge";
+import {
+  createAutomergeFieldValue,
+  loadAutomergeFieldDoc,
+  materializeAutomergeFieldValue,
+  mergeAutomergeFieldValues,
+  saveAutomergeFieldDoc,
+} from "../src/crdt-automerge.js";
+
+const type = "camino.CrdtJson";
+
+test("Automerge CRDT fields lift plain values into stored envelopes", () => {
+  const stored = createAutomergeFieldValue({ title: "draft" }, type);
+
+  assert.equal(stored.$caminoCrdtType, type);
+  assert.equal(stored.$caminoCrdtEncoding, "base64");
+  assert.deepEqual(materializeAutomergeFieldValue(stored, type), {
+    title: "draft",
+  });
+});
+
+test("Automerge CRDT fields merge divergent saved documents", () => {
+  const base = loadAutomergeFieldDoc(
+    createAutomergeFieldValue({ left: false, right: false }, type),
+    type,
+  );
+  const left = Automerge.change(Automerge.clone(base, "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"), (doc) => {
+    (doc.value as { left: boolean }).left = true;
+  });
+  const right = Automerge.change(Automerge.clone(base, "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"), (doc) => {
+    (doc.value as { right: boolean }).right = true;
+  });
+
+  const result = mergeAutomergeFieldValues({
+    existing: saveAutomergeFieldDoc(left, type),
+    incoming: saveAutomergeFieldDoc(right, type),
+    type,
+  });
+
+  assert.deepEqual(result.materialized, { left: true, right: true });
+  assert.deepEqual(materializeAutomergeFieldValue(result.stored, type), {
+    left: true,
+    right: true,
+  });
+});