assertSnapshot fails to match carriage return

[OzzieOrca]

Describe the bug If you pass the CR character \r to assertSnapshot, it saves the snapshot fine but then immediately fails to match the snapshot.

I ran into this by trying to snapshot the output of stringify(...) from https://deno.land/[email protected]/csv/mod.ts which apparently output CRLFs (\r\n).

Steps to Reproduce

1. Create a file (crlf.test.ts) with the contents

   import { assertSnapshot } from 'https://deno.land/[email protected]/testing/snapshot.ts';
   
   Deno.test('CR failure', async (t) => {
     await assertSnapshot(t, '\r');
   });
   

2. Run deno test --allow-read --allow-write cr.test.ts -- --update which returns

   running 1 test from ./cr.test.ts
   CR failure ... ok (2ms)
   ------- output -------
   
   > 1 snapshot updated.
   
   ok | 1 passed | 0 failed (4ms)
   

   and saves __snapshots__/cr.test.ts.snap with

   export const snapshot = {};
   
   snapshot[`CR failure 1`] = `
   "
   "
   `;
   

3. Run deno test --allow-read cr.test.ts which returns:

   running 1 test from ./cr.test.ts
   CR failure ... FAILED (6ms)
   
    ERRORS 
   
   CR failure => ./cr.test.ts:3:6
   error: AssertionError: Snapshot does not match:
   
   
       [Diff] Actual / Expected
   
   
   -   "
   +   "
       "
   
       throw new AssertionError(
             ^
       at assertSnapshot (https://deno.land/[email protected]/testing/snapshot.ts:591:11)
       at async file:///home/scotty/code/Toptal/FoodNoms/macrosai-supabase/cr.test.ts:4:3
   
    FAILURES 
   
   CR failure => ./cr.test.ts:3:6
   
   FAILED | 0 passed | 1 failed (8ms)
   
   error: Test failed
   

Expected behavior

The test should succeed after the snapshot has been updated.

Environment

• OS: Ubuntu 22.04.3 LTS
• deno version: 1.39.1
• std version: 0.212.0

[javihernant]

I'm taking a look at this one

[javihernant]

The culprit seems to be here. When .ts.snap is written, an actual "\r" is written to the file. However, when importing it reads a "\n". import bugs have to be fixed in the actual runtime (not in deno_std), right? Note: this one was fun to find! ^^

[kt3k]

@javihernant Interesting finding! Can you create an issue in denoland/deno with a minimal repro example?

[kt3k]

hmm looks like Deno ignoring \r in string literal is not a bug. Maybe we should escape \r when serializing it

[OzzieOrca]

Sounds like assertSnapshot should strip (or escape somehow?) \r characters before comparing and storing snapshots. At least that's my takeaway from https://github.com/denoland/deno/issues/22575#issuecomment-2162989848.