Add mozjpeg test for progressive images

packages/mozjpeg/__tests__/index.test.ts

@@ -31,6 +31,7 @@ describe('mozjpeg', () => {
  expect(metadata.width).toBe(width);
  expect(metadata.height).toBe(height);
  expect(metadata.channels).toBe(3);
+ expect(metadata.isProgressive).toBe(true);
  });
  });
 
@@ -108,4 +109,30 @@ describe('mozjpeg', () => {
  expect(metadata.height).toBe(height);
  expect(metadata.channels).toBe(1);
  });
+
+ it('uses baseline if progressive is disabled', async () => {
+ const {
+ data,
+ info: { width, height, channels },
+ } = await getRawImage('images/medium.jpg');
+ const originalSize = getFileSize('images/medium.jpg');
+ const originalMetadata = await getImageMetadata('images/medium.jpg');
+ expect(originalMetadata.channels).toBe(3);
+
+ const result = await encode(data, { width, height, channels }, { progressive: false });
+ const encodedPath = writeTmpBuffer(result, 'medium-baseline.jpg');
+ const encodedSize = getFileSize(encodedPath);
+
+ // expect the image size to be between 1/4 and 3/4 of the original image
+ expect(encodedSize).toBeLessThan(originalSize * 0.75);
+ expect(encodedSize).toBeGreaterThan(originalSize * 0.25);
+
+ // check if the image is still a valid jpeg image
+ const metadata = await getImageMetadata(encodedPath);
+ expect(metadata.format).toBe('jpeg');
+ expect(metadata.width).toBe(width);
+ expect(metadata.height).toBe(height);
+ expect(metadata.channels).toBe(3);
+ expect(metadata.isProgressive).toBe(false);
+ });
 });