add missing unit test suite

tests/backups/parse-restic-diff.test.ts

@@ -0,0 +1,48 @@
+/**
+ * Unit tests for parseResticDiff — turns `restic diff --json` (and the plain-text
+ * fallback) into the {added, removed, modified, metadataChanged} shape the diff
+ * modal renders. A regression here shows up as the compare dialog spinning forever
+ * (the client reads diff.added.length on an unparsed {raw} blob).
+ */
+import { describe, it, expect } from 'bun:test';
+import { parseResticDiff } from '../../src/lib/server/backups/helpers';
+
+describe('parseResticDiff — restic --json change lines', () => {
+	it('buckets +/-/M and metadata-only (U/T) modifiers', () => {
+		const raw = [
+			JSON.stringify({ message_type: 'change', path: '/volumes/data/new.txt', modifier: '+' }),
+			JSON.stringify({ message_type: 'change', path: '/volumes/data/gone.txt', modifier: '-' }),
+			JSON.stringify({ message_type: 'change', path: '/volumes/data/edited.txt', modifier: 'M' }),
+			JSON.stringify({ message_type: 'change', path: '/volumes/data/perms.txt', modifier: 'U' }),
+			JSON.stringify({ message_type: 'statistics', changed_files: 3 }), // must be ignored
+		].join('\n');
+		const d = parseResticDiff(raw);
+		expect(d.added).toEqual(['/volumes/data/new.txt']);
+		expect(d.removed).toEqual(['/volumes/data/gone.txt']);
+		expect(d.modified).toEqual(['/volumes/data/edited.txt']);
+		expect(d.metadataChanged).toEqual(['/volumes/data/perms.txt']);
+	});
+
+	it('ignores blank lines and non-change JSON', () => {
+		const raw = '\n' + JSON.stringify({ message_type: 'statistics' }) + '\n\n';
+		const d = parseResticDiff(raw);
+		expect(d.added).toHaveLength(0);
+		expect(d.removed).toHaveLength(0);
+		expect(d.modified).toHaveLength(0);
+		expect(d.metadataChanged).toHaveLength(0);
+	});
+
+	it('falls back to plain-text restic diff ("<modifier>    <path>")', () => {
+		const raw = ['+    /a', '-    /b', 'M    /c', 'T    /d'].join('\n');
+		const d = parseResticDiff(raw);
+		expect(d.added).toEqual(['/a']);
+		expect(d.removed).toEqual(['/b']);
+		expect(d.modified).toEqual(['/c']);
+		expect(d.metadataChanged).toEqual(['/d']);
+	});
+
+	it('empty diff → all empty arrays (identical snapshots)', () => {
+		const d = parseResticDiff('');
+		expect(d).toEqual({ added: [], removed: [], modified: [], metadataChanged: [] });
+	});
+});