add comparable tests for MongoLSN

modules/module-mongodb/test/src/resume.test.ts

@@ -0,0 +1,78 @@
+import { MongoLSN, ZERO_LSN } from '@module/common/MongoLSN.js';
+import { mongo } from '@powersync/lib-service-mongodb';
+import { describe, expect, test } from 'vitest';
+
+describe('mongo lsn resume tokens', () => {
+  test('LSN with resume tokens should be comparable', () => {
+    // Values without a resume token should be comparable
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(1)
+      }).comparable <
+        new MongoLSN({
+          timestamp: mongo.Timestamp.fromNumber(10)
+        }).comparable
+    ).true;
+
+    // Values with resume tokens should correctly compare
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(1),
+        resume_token: { _data: 'resume1' }
+      }).comparable <
+        new MongoLSN({
+          timestamp: mongo.Timestamp.fromNumber(10),
+          resume_token: { _data: 'resume2' }
+        }).comparable
+    ).true;
+
+    // The resume token should not affect comparison
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(1),
+        resume_token: { _data: '2' }
+      }).comparable <
+        new MongoLSN({
+          timestamp: mongo.Timestamp.fromNumber(10),
+          resume_token: { _data: '1' }
+        }).comparable
+    ).true;
+
+    // Resume token should not be required for comparison
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(10),
+        resume_token: { _data: '2' }
+      }).comparable > // Switching the order to test this case
+        new MongoLSN({
+          timestamp: mongo.Timestamp.fromNumber(9)
+        }).comparable
+    ).true;
+
+    // Comparison should be backwards compatible with old LSNs
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(10),
+        resume_token: { _data: '2' }
+      }).comparable > ZERO_LSN
+    ).true;
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(10),
+        resume_token: { _data: '2' }
+      }).comparable >
+        new MongoLSN({
+          timestamp: mongo.Timestamp.fromNumber(1)
+        }).comparable.split('|')[0] // Simulate an old LSN
+    ).true;
+    expect(
+      new MongoLSN({
+        timestamp: mongo.Timestamp.fromNumber(1),
+        resume_token: { _data: '2' }
+      }).comparable <
+        new MongoLSN({
+          timestamp: mongo.Timestamp.fromNumber(10)
+        }).comparable.split('|')[0] // Simulate an old LSN
+    ).true;
+  });
+});