Remove undocumented app metadata from scrobble payloads

[Copilot]

Scrobble payloads were including app_version and date fields not present in the Trakt API docs. When either is None, the API rejects the request with 400 {"error": "Expected string, received null"}.

Fixes #100

Changes

• trakt/sync.py: Scrobbler._post() now builds the payload with only progress + media JSON:

  # before
  payload = dict(progress=self.progress, app_version=self.version, date=self.date)
  # after
  payload = dict(progress=self.progress)

• tests/test_scrobble.py: Added test_scrobbler_payload_excludes_app_metadata — patches api().post to capture the outgoing payload and asserts app_version, app_date, and date are absent.

Original prompt

Create a pull request in repository glensc/python-pytrakt to fix issue #100: scrobble payloads currently include undocumented app metadata that can be null and cause Trakt API 400 responses.

Context:

• Issue: app_version and app_date are not in Trakt API doc and may raise 400 error
• Repository issue URL: app_version and app_date are not in Trakt API doc and may raise 400 error #100
• The issue report notes that Trakt's /scrobble/start payload documentation only includes the media object and progress, and that sending app_version: null can trigger 400 {"error": "Expected string, received null"}.

Relevant code identified:

• trakt/sync.py: Scrobbler._post() currently builds payloads with progress, app_version, and date before adding the media JSON.
• trakt/movies.py and trakt/tv.py: public scrobble() methods pass app_version and app_date into Scrobbler; changing these call signatures is optional unless needed for compatibility. Keep scope minimal.
• checkin_media() also uses app_version and app_date, but issue app_version and app_date are not in Trakt API doc and may raise 400 error #100 is specifically about scrobble payloads; do not change checkin behavior unless strictly necessary.
• Existing scrobble tests are in tests/test_scrobble.py. Mock payload data also exists in tests/mock_data/scrobble.json.

Requirements:

1. Implement the smallest safe fix so scrobble requests no longer send undocumented app_version / app_date metadata that may be null.
2. Preserve backward compatibility of the public API as much as possible; avoid unnecessary signature changes if the fix can be isolated to request payload generation.
3. Add or update tests to prevent regressions and ensure scrobble payloads do not include those fields.
4. Keep commits atomic and as small as possible.
5. Follow commit message guidance from https://chris.beams.io/git-commit — concise imperative subject, focused per commit.

Expected likely approach:

• Update Scrobbler._post() in trakt/sync.py so the payload contains only progress plus media.to_json_singular() content.
• Add/update tests in tests/test_scrobble.py (and any fixture/mock data if needed) to verify the scrobble payload shape and absence of app_version, app_date, or stray date fields.

Deliverable:

• Open a PR against main in glensc/python-pytrakt with atomic commits and a clear PR description referencing issue app_version and app_date are not in Trakt API doc and may raise 400 error #100.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Propose fix for @glensc/python-pytrakt/issues/100 issue.

When making commits, make the commits atomic, smallest as possible following guidance from https://chris.beams.io/git-commit

Assistant: Proposed fix: stop sending undocumented app_version / app_date fields in scrobble payloads, and add a regression test that would fail if those fields reappear.

Why this is the right fix

• The current scrobble payload is built in Scrobbler._post() and includes app_version plus date unconditionally. That does not match the issue report or the documented Trakt scrobble payload shape.
• checkin still appears intentionally built around app_version / app_date, so I would not change checkin as part of issue app_version and app_date are not in Trakt API doc and may raise 400 error #100 unless you want to broaden scope.
• This keeps the change small and atomic.

Minimal code change

In trakt/sync.py, change Scrobbler._post() from building:

payload = dict(progress=self.progress, app_version=self.version,
               date=self.date)
payload.update(self.media.to_json_singular())
response = yield uri, payload

to:

payload = dict(progress=self.progress)
payload.update(self.media.to_json_singular())
response = yield uri, payload

Regression test to add

Add a test in tests/test_scrobble.py asserting the generated payload does not contain those fields:

# -*- coding: utf-8 -*-
from trakt.movies import Movie
from trakt.sync import Scrobbler


def test_scrobble():
    """test the Scrobbler class's workflow"""
    guardians = Movie('Guardians of the Galaxy', year=2014)
    scrobbler = Scrobbler(guardians, 1.0, '1.0.0', '2015-02-01')
    scrobbler.start()
    scrobbler.update(50.0)
    scrobbler.pause()
    scrobbler.start()
    scrobbler.stop()
    scrobbler.start()
    scrobbler.finish()


def test_scrobbler_context_manager():
    """test the Scrobbler when used as a context manager"""
    guardians = Movie('Guardians of the Galaxy', year=2014)
    with Scrobbler(guardians, 0.0, '1.0.0', '2015-02-01') as scrob:
        for i in range(10):
            scrob.update(i*10)


def test_scrobbler_payload_excludes_app_metadata():
    """scrobble payload should not send undocumented app metadata"""
    guardians = Movie('Guardi...

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