test: file test (#7)

tests/file.spec.ts

@@ -0,0 +1,36 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { toDataURL, toText, toArrayBuffer } from '../src';
+
+describe('file', () => {
+  let file: File;
+
+  beforeEach(() => {
+    const blob = new Blob(['Hello, World!'], { type: 'text/plain' });
+    file = new File([blob], 'hello.txt', { type: 'text/plain' });
+  });
+
+  describe('toDataURL', () => {
+    it('should convert file to data URL', async () => {
+      const dataURL = await toDataURL(file);
+      expect(dataURL).toMatch(/^data:text\/plain;base64,/);
+    });
+  });
+
+  describe('toText', () => {
+    it('should read file as text', async () => {
+      const text = await toText(file);
+      expect(text).toBe('Hello, World!');
+    });
+  });
+
+  describe('toArrayBuffer', () => {
+    it('should read file as array buffer', async () => {
+      const arrayBuffer = await toArrayBuffer(file);
+      expect(arrayBuffer).toBeInstanceOf(ArrayBuffer);
+
+      const uint8Array = new Uint8Array(arrayBuffer);
+      const text = new TextDecoder().decode(uint8Array);
+      expect(text).toBe('Hello, World!');
+    });
+  });
+});