test: add integration test for ledgerToTimestamp (#461)

src/utils/__tests__/stellarLedger.integration.test.ts

@@ -0,0 +1,40 @@
+import { describe, it, expect } from 'vitest';
+import { ledgerToTimestamp } from '../stellarLedger.utils';
+
+describe('ledgerToTimestamp - Integration Test with Known Values', () => {
+	// A known reference point: ledger 50000000 and some arbitrary timestamp.
+	const KNOWN_REFERENCE_LEDGER = 50000000;
+	// e.g. 2024-01-01T00:00:00.000Z
+	const KNOWN_REFERENCE_TIMESTAMP = new Date('2024-01-01T00:00:00.000Z').getTime();
+
+	it('returns exactly the reference timestamp when ledger equals reference', () => {
+		const result = ledgerToTimestamp(
+			KNOWN_REFERENCE_LEDGER,
+			KNOWN_REFERENCE_LEDGER,
+			KNOWN_REFERENCE_TIMESTAMP
+		);
+		expect(result.getTime()).toBe(KNOWN_REFERENCE_TIMESTAMP);
+	});
+
+	it('returns correctly estimated future date (100 ledgers ahead)', () => {
+		const futureLedger = KNOWN_REFERENCE_LEDGER + 100;
+		const result = ledgerToTimestamp(
+			futureLedger,
+			KNOWN_REFERENCE_LEDGER,
+			KNOWN_REFERENCE_TIMESTAMP
+		);
+		const expectedTimestamp = KNOWN_REFERENCE_TIMESTAMP + 100 * 5000;
+		expect(result.getTime()).toBe(expectedTimestamp);
+	});
+
+	it('returns correctly estimated past date (100 ledgers behind)', () => {
+		const pastLedger = KNOWN_REFERENCE_LEDGER - 100;
+		const result = ledgerToTimestamp(
+			pastLedger,
+			KNOWN_REFERENCE_LEDGER,
+			KNOWN_REFERENCE_TIMESTAMP
+		);
+		const expectedTimestamp = KNOWN_REFERENCE_TIMESTAMP - 100 * 5000;
+		expect(result.getTime()).toBe(expectedTimestamp);
+	});
+});