Added Basic Visualization tests

[Sahil-Chhoker]

Summary

Adds visualization tests for example models.

Motive

Part of #2741.

Implementation

Adds basic tests to confirm the data is passed onto the the plot components and space component is changing with step or not.

Additional Notes

Ran every test 15 times (total 135 times), found no flaky tests.

Summary by CodeRabbit

• Tests

  • Added automated tests to verify that visualizations for multiple agent-based models update correctly as the models progress.
  • Introduced visual regression checks using Playwright for models such as Schelling, Wolf-Sheep, Boid Flockers, Boltzmann Wealth, Virus on Network, Conway’s Game of Life, Epstein Civil Violence, Sugarscape G1mt, and Prisoner’s Dilemma.

• Chores

  • Expanded development dependencies to include additional testing tools for Playwright and IPython widgets.

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Walkthrough

The changes introduce a new visualization test suite for various Mesa agent-based models in a new test file. This suite uses Playwright and Solara to render and capture screenshots of visualizations before and after model progression, verifying that the visual output changes as expected. The test suite covers multiple example models, each with its own setup and portrayal logic. Additionally, the development dependencies in the pyproject.toml file are updated to include pytest-playwright, pytest-ipywidgets, and playwright to support these new testing capabilities.

Changes

File(s)	Change Summary
pyproject.toml	Added pytest-playwright, pytest-ipywidgets, and playwright to the dev dependency group.
tests/test_examples_viz.py	Added new test suite for Mesa model visualizations. Includes a helper function and individual tests for various example models.

Sequence Diagram(s)

sequenceDiagram
    participant Tester as pytest
    participant Model as Mesa Model
    participant Viz as SpaceMatplotlib/PlotMatplotlib
    participant Solara as Solara Test Fixture
    participant Browser as Playwright Page

    Tester->>Model: Initialize with seed
    Tester->>Viz: Create initial visualization
    Viz->>Solara: Display visualization
    Solara->>Browser: Render and capture screenshot
    Tester->>Model: Step model N times
    Tester->>Viz: Create updated visualization
    Viz->>Solara: Display updated visualization
    Solara->>Browser: Render and capture updated screenshot
    Tester->>Tester: Compare screenshots (assert visual change)

Loading

Poem

In the warren of tests, a new suite appears,
With Playwright and Solara, it conquers old fears.
Models parade, their visuals in tow,
Snapshots are taken, before and aglow.
With every step forward, the agents all dance—
Hopping through pixels, they change at a glance!
🐇✨

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[Sahil-Chhoker]

@coderabbitai full review

[coderabbitai]

✅ Actions performed

Full review triggered.

[coderabbitai]

Actionable comments posted: 3

🧹 Nitpick comments (2)

tests/test_examples_viz.py (2)

63-70: Potential memory-leak of Matplotlib figures

You create two new SpaceMatplotlib and optionally PlotMatplotlib instances per test without closing the previous figures; after dozens of tests this can exhaust the Matplotlib figure manager and memory.

Add an explicit plt.close('all') (or call the components’ close() method if they expose one) right after you finish the first screenshot and again after the second.

---

26-34: Minor: default steps=5 may hide bugs in slow-evolving models

Some models (e.g. Conway’s with sparse seeds) need more than 5 steps for visible change. Consider exposing steps as a parameter in each test call so that individual tests can override the default when required.

📜 Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 94c56a3 and f8a7a4f.

📒 Files selected for processing (2)

• pyproject.toml (1 hunks)
• tests/test_examples_viz.py (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (1)

• GitHub Check: build (windows, 3.13)

🔇 Additional comments (2)

pyproject.toml (1)

66-69: Add Playwright browser installation step & consider pinning versions

1. Adding playwright to dev is necessary for the new screenshot tests, but the tests will still fail on fresh CI runners unless the browsers are installed (playwright install --with-deps or python -m playwright install).
   • Please ensure the CI pipeline (or a post-install hook) downloads the browsers or the tests will error with “Executable doesn’t exist”.
2. None of the three new dev dependencies is version-pinned while most of your runtime deps are. Un-pinned UI-automation libraries tend to ship breaking changes frequently; consider pinning to the latest known-good versions or adding an upper bound.

Would you like a small CI snippet showing how to cache & install the Playwright browsers?

tests/test_examples_viz.py (1)

90-97: Base-64 inequality check can still be flaky on headless renderers

Anti-aliasing, timestamps, or background metadata may change between runs even if the visual content is identical, giving false positives/negatives. If you encounter flakes later:

• Hash the image array after stripping metadata (e.g. via Pillow).
• Or compare perceptual hashes (e.g. imagehash.phash) to tolerate pixel-level noise while still catching genuine changes.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 +1.1% [-0.1%, +2.2%]	🔵 -0.7% [-0.9%, -0.5%]
BoltzmannWealth	large	🔵 +0.3% [-0.5%, +1.1%]	🔵 +0.1% [-2.0%, +2.1%]
Schelling	small	🔵 -0.1% [-0.3%, +0.1%]	🔵 -0.7% [-1.0%, -0.4%]
Schelling	large	🔵 -0.0% [-0.6%, +0.6%]	🔵 -1.5% [-3.1%, -0.1%]
WolfSheep	small	🔵 +0.2% [-0.2%, +0.6%]	🔵 +0.1% [-0.2%, +0.3%]
WolfSheep	large	🔵 +1.7% [+0.9%, +2.5%]	🔵 +1.0% [-0.6%, +2.3%]
BoidFlockers	small	🔵 +0.4% [-0.4%, +1.2%]	🔵 +0.8% [+0.5%, +1.0%]
BoidFlockers	large	🔵 +0.4% [-0.2%, +1.0%]	🔵 -0.1% [-0.5%, +0.3%]

[Sahil-Chhoker]

Tests became a lot faster by only replacing time.sleep(0.2) with page_session.wait_for_selector("img")

(I run one test 15 times to check if the test is flaky or not, but there are only 9 tests)

[EwoutH]

Thanks a lot for this PR!

@Corvince any chance you could review?