merge files inital commit

src/merge/mergeQueueHelpers.test.ts

@@ -0,0 +1,82 @@
+import { describe, expect, it } from 'vitest';
+import type { MergeQueueItem } from './mergeTypes';
+import {
+  canMergeQueue,
+  clampMergeInsertAt,
+  createMergedPdfName,
+  getReadyMergeQueuePdfs,
+  moveMergeQueueItem,
+} from './mergeQueueHelpers';
+
+function makeItem(
+  id: string,
+  status: MergeQueueItem['status']
+): MergeQueueItem {
+  return {
+    id,
+    file: new File(['x'], `${id}.pdf`, { type: 'application/pdf' }),
+    name: `${id}.pdf`,
+    size: 1,
+    pageCount: status === 'ready' ? 1 : null,
+    pdf:
+      status === 'ready'
+        ? {
+            id: `pdf-${id}`,
+            name: `${id}.pdf`,
+            // The helper tests never dereference the PDFDocument.
+            doc: {} as never,
+            pageCount: 1,
+            arrayBuffer: new ArrayBuffer(0),
+          }
+        : null,
+    status,
+  };
+}
+
+describe('merge queue helpers', () => {
+  it('moves queued items up and down without mutating the original array', () => {
+    const items = [
+      makeItem('a', 'ready'),
+      makeItem('b', 'ready'),
+      makeItem('c', 'ready'),
+    ];
+
+    expect(moveMergeQueueItem(items, 'b', 'up').map((item) => item.id)).toEqual(
+      ['b', 'a', 'c']
+    );
+    expect(
+      moveMergeQueueItem(items, 'b', 'down').map((item) => item.id)
+    ).toEqual(['a', 'c', 'b']);
+    expect(items.map((item) => item.id)).toEqual(['a', 'b', 'c']);
+  });
+
+  it('only allows merging when every queued item is ready', () => {
+    const readyItems = [makeItem('a', 'ready'), makeItem('b', 'ready')];
+    const mixedItems = [makeItem('a', 'ready'), makeItem('b', 'loading')];
+
+    expect(canMergeQueue(readyItems)).toBe(true);
+    expect(getReadyMergeQueuePdfs(readyItems)).toHaveLength(2);
+    expect(canMergeQueue(mixedItems)).toBe(false);
+    expect(canMergeQueue([])).toBe(false);
+  });
+
+  it('clamps one-based merge positions to zero-based insert slots', () => {
+    expect(clampMergeInsertAt('1', 10)).toBe(0);
+    expect(clampMergeInsertAt('5', 10)).toBe(4);
+    expect(clampMergeInsertAt('99', 10)).toBe(10);
+    expect(clampMergeInsertAt('-10', 10)).toBe(0);
+    expect(clampMergeInsertAt('not-a-number', 10)).toBe(10);
+  });
+
+  it('creates readable merged PDF filenames', () => {
+    expect(createMergedPdfName('base.pdf', ['a.pdf', 'b.pdf'], 'append')).toBe(
+      'base_plus_2_pdfs.pdf'
+    );
+    expect(createMergedPdfName('base.pdf', ['a.pdf'], 'overwrite')).toBe(
+      'a_merged.pdf'
+    );
+    expect(createMergedPdfName(null, ['a.pdf', 'b.pdf'], 'overwrite')).toBe(
+      'merged_2_pdfs.pdf'
+    );
+  });
+});