[BUG] No Diff file if image size is different

Context:

• Playwright Version: v1.27.0
• Operating System: Linux
• Node.js version: 16.17.1
• Browser: Chromium

Code Snippet My basic test.

const {chromium, webkit, firefox} = require('playwright');
// my config is in a different file, but this line is relevant. 
const config = { use: { viewPort: { width: 1280, height: 4462 }};

(async () => {
  const browser = await chromium.launch();
  const context = await browser.newContext();
  const page = await context.newPage();
  
  await expect(page).toHaveScreenshot({
     maxDiffPixelRatio: 0.03,
     fullPage: true,
     animations: "disabled",
  });
})();

Describe the bug

Occasionally my tests seem to fail where the height of the page is incorrect, however, playwright does not generate a diff file, i think because the compared and expected images are the wrong height. I get the following output

    Error: Screenshot comparison failed:

      Expected an image 1280px by 6061px, received 1280px by 6068px. 

    Call log:
      - expect.toHaveScreenshot with timeout 5000ms
      -   verifying given screenshot expectation
      - taking page screenshot
      -   disabled all CSS animations
      - Expected an image 1280px by 6061px, received 1280px by 6068px. 
      - waiting 100ms before taking screenshot
      - taking page screenshot
      -   disabled all CSS animations
      - captured a stable screenshot
      - Expected an image 1280px by 6061px, received 1280px by 6068px.

But no diff file.

[atlowl]

@jfgreffier, yep - i do actually like that. I see your point about being intentional not to provide a diff file when they are different sizes. I used a fixed view port to try and get around that issue. Guess i can close this as being worked on?

[jameskip]

I think the exclusion of a diff file is intentional. I’m not aware of a scenario where if the dimensions of the window are incorrect a diff would be useful.