fix(server): sorting notes by custom attribute with missing value not idempotent

src/services/tree.spec.ts

@@ -0,0 +1,72 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import becca_mocking from "../../spec/support/becca_mocking.js";
+import becca from "../becca/becca.js";
+import BBranch from "../becca/entities/bbranch.js";
+import BNote from "../becca/entities/bnote.js";
+import tree from "./tree.js";
+import cls from "./cls.js";
+
+describe("Tree", () => {
+    let rootNote!: any;
+
+    beforeEach(() => {
+        becca.reset();
+
+        rootNote = new becca_mocking.NoteBuilder(new BNote({
+            noteId: "root",
+            title: "root",
+            type: "text"
+        }))
+        new BBranch({
+            branchId: "none_root",
+            noteId: "root",
+            parentNoteId: "none",
+            notePosition: 10
+        });
+
+        vi.mock("./sql.js", () => {
+            return {
+                default: {
+                    transactional: (cb) => {
+                        cb();
+                    },
+                    execute: (...args) => { },
+                    replace: (...args) => { },
+                    getMap: (...args) => { }
+                }
+            }
+        });
+
+        vi.mock("./sql_init.js", () => {
+            return {
+                dbReady: () => { console.log("Hello world") }
+            }
+        });
+    });
+
+    it("custom sort order is idempotent", () => {
+        rootNote.label("sorted", "order");
+
+        // Add values which have a defined order.
+        for (let i=0; i<=5; i++) {
+            rootNote.child(becca_mocking.note(String(i)).label("order", String(i)));
+        }
+
+        // Add a few values which have no defined order.
+        for (let i=6; i<10; i++) {
+            rootNote.child(becca_mocking.note(String(i)));
+        }
+
+        const expectedOrder = [ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' ];
+
+        // Sort a few times to ensure that the resulting order is the same.
+        for (let i=0; i<5; i++) {
+            cls.init(() => {
+                tree.sortNotesIfNeeded(rootNote.note.noteId);
+            });
+
+            const order = rootNote.note.children.map((child) => child.title);
+            expect(order).toStrictEqual(expectedOrder);
+        }
+    });
+});