motief/docs/solutions/build-errors/uv-lock-pytest-missing-source-2026-04-05.md

title	module	component	problem_type	severity	date	tags
uv.lock parse error due to pytest entry missing source	tooling	tooling	build_error	medium	2026-04-05	[uv lockfile pytest packaging streamlit]

Problem

Running uv commands failed with a parse error in uv.lock caused by an ambiguous/malformed pytest entry that lacked a proper source field and conflicted with another package entry.

Symptoms

• uv run streamlit run Home.py failed with: "Dependency pytest has missing source field but has more than one matching package".
• uv lock and uv add also failed because uv.lock could not be parsed.

What didn't work

• Attempting uv add "pytest>=9.0.2" --dev failed because the lockfile parser errored before the command could modify anything.
• Manual edits to uv.lock were used as a temporary stop-gap (allowed uv to run) but are not a durable solution because uv.lock is generated.

Solution

1. Regenerate the lockfile from pyproject.toml so uv.lock and project metadata are consistent:

   • Run: uv lock
   • Inspect the resulting uv.lock to ensure pytest appears as a single [[package]] entry with a source field and expected hashes.

2. Commit the regenerated lock locally (do not push without review):

   • git add uv.lock
   • git commit -m "chore: regenerate uv.lock (resolve pytest source ambiguity)"

Why this works

• uv.lock is the canonical, generated lockfile. The parser expects each package entry to have an unambiguous source so uv can resolve hashes and reproducible installs. Regenerating produces a consistent lockfile derived from pyproject.toml and resolves duplicated/malformed entries.
• Manual edits fix symptoms but can be overwritten or lead to inconsistent state; regenerating ensures upstream metadata and lockfile match the resolver's expectations.

Prevention

• Avoid hand-editing uv.lock. When a lockfile parse error appears, prefer regenerating with uv lock.
• Add a lightweight CI check to ensure uv lock --check (or uv lock with no changes) passes before merging changes that touch dependencies or the lockfile.
• Make pytest (and other dev tools) authoritative in pyproject.toml under dependency-groups.dev so the resolver has a single source of truth.

Verification

• After regeneration, verify uv commands work and tests run:

  • uv run streamlit run Home.py → Streamlit should start and print Local/Network URL
  • .venv/bin/python -m pytest tests/ -q → Confirm tests run (example in this run: 171 passed, 2 skipped).

Related files

• uv.lock
• pyproject.toml

If you want, I can:

1. Run the Streamlit verification now, or
2. Propose a small CI job snippet to enforce uv lock --check, or
3. Create a short PR description if you want this committed change pushed and opened as a PR.