#470 A Jolting Episode

6 snips

Feb 23, 2026

Inline-snapshot testing for complex data lets tests store expected structures right in the test code. Jolt provides terminal battery intelligence with power, process tracking, and historical graphs for macOS and Linux. Ruff can format Python code blocks inside Markdown safely. Act lets you run GitHub Actions workflows locally using Docker for faster feedback.

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INSIGHT

Inline Snapshot Testing Keeps Expected Structures In Tests

Snapshot testing embeds expected outputs directly into pytest tests using inline-snapshot so you can visually inspect expected complex data structures in-place.
Run pytest with --inline-snapshot=fix to populate the inline dict, then run normally to compare against the collected snapshot for regression checks.

ADVICE

Always Review Updated Inline Snapshots

When updating snapshots, always manually inspect the inline snapshot after running with --inline-snapshot=fix to avoid blindly accepting unintended changes.
Brian warns that without inspection snapshots become mere change detectors rather than meaningful assertions.

ANECDOTE

Michael Shows Jolt Monitoring His MacBook

Michael demonstrates Jolt running on his MacBook Air showing battery percent, time remaining, cycle count, temperature and real-time watt draw with CPU/GPU breakdown.
He points out Vivaldi and other processes' energy impact and a moving graph of power and battery trends.

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Topics covered in this episode:

Better Python tests with inline-snapshot
jolt Battery intelligence for your laptop
Markdown code formatting with ruff
act - run your GitHub actions locally
Extras
Joke

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About the show

Sponsored by us! Support our work through:

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Michael: @mkennedy@fosstodon.org / @mkennedy.codes (bsky)
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Show: @pythonbytes@fosstodon.org / @pythonbytes.fm (bsky) Join us on YouTube at pythonbytes.fm/live to be part of the audience. Usually Monday at 11am PT. Older video versions available there too. Finally, if you want an artisanal, hand-crafted digest of every week of the show notes in email form? Add your name and email to our friends of the show list, we'll never share it.

Brian #1: Better Python tests with inline-snapshot

Alex Hall, on Pydantic blog
Great for testing complex data structures

Allows you to write a test like this:

from inline_snapshot import snapshot
def test_user_creation():
    user = create_user(id=123, name="test_user")
    assert user.dict() == snapshot({})

Then run pytest --inline-snapshot=fix

And the library updates the test source code to look like this:

def test_user_creation():
    user = create_user(id=123, name="test_user")
    assert user.dict() == snapshot({
        "id": 123,
        "name": "test_user",
        "status": "active"
    })

Now, when you run the code without “fix” the collected data is used for comparison
Awesome to be able to visually inspect the test data right there in the test code.
Projects mentioned

Michael #2: jolt Battery intelligence for your laptop

Support for both macOS and Linux
Battery Status — Charge percentage, time remaining, health, and cycle count
Power Monitoring — System power draw with CPU/GPU breakdown
Process Tracking — Processes sorted by energy impact with color-coded severity
Historical Graphs — Track battery and power trends over time
Themes — 10+ built-in themes with dark/light auto-detection
Background Daemon — Collect historical data even when the TUI isn't running
Process Management — Kill energy-hungry processes directly

Brian #3: Markdown code formatting with ruff

Suggested by Matthias Schoettle
ruff can now format code within markdown files
Will format valid Python code in code blocks marked with python, py, python3 or py3.
Also recognizes pyi as Python type stub files.
Includes the ability to turn off formatting with comment  ,  blocks.
Requires preview mode
```
[tool.ruff.lint]
preview = true
```

Michael #4: act - run your GitHub actions locally

Run your GitHub Actions locally! Why would you want to do this? Two reasons:
- Fast Feedback - Rather than having to commit/push every time you want to test out the changes you are making to your .github/workflows/ files (or for any changes to embedded GitHub actions), you can use act to run the actions locally. The environment variables and filesystem are all configured to match what GitHub provides.
- Local Task Runner - I love make. However, I also hate repeating myself. With act, you can use the GitHub Actions defined in your .github/workflows/ to replace your Makefile!
When you run act it reads in your GitHub Actions from .github/workflows/ and determines the set of actions that need to be run.
- Uses the Docker API to either pull or build the necessary images, as defined in your workflow files and finally determines the execution path based on the dependencies that were defined.
- Once it has the execution path, it then uses the Docker API to run containers for each action based on the images prepared earlier.
- The environment variables and filesystem are all configured to match what GitHub provides.

Extras

Michael:

Winter is coming: Frozendict accepted
Django ORM stand-alone
Command Book app announcement post

Joke: Plug ‘n Paste