goringandSmit Barmase
86aae77e5e
> **AI disclosure:** I used Claude (Anthropic) to write this change, its test, and draft this PR description, after my own app shipped a rendering bug that only reproduces on 1x displays — every test built on gpui's test platform renders at a fixed 2.0 scale factor, so the bug was invisible to an otherwise thorough offscreen test suite. I reviewed the diff, ran the tests myself, and understand and take responsibility for the change, per Zed's [AI Policy](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#ai-policy). # Objective - `TestWindow::scale_factor()` has returned a hardcoded `2.0` since the test platform's inception (`75f0670dd`, 2024-01-03), with no way for a test to change it. Rendering behavior that only appears on 1x displays — device-grid rounding, pixel snapping — can't be exercised: an error of one device pixel is the full width of a hairline at 1x and half a logical pixel at 2x, so this class of bug passes every test and ships. - `Window::set_scale_factor` (`24058c865`, #61348, 2025-08) exists but doesn't cover this: it overrides only the `Window`'s cached copy, so the next `bounds_changed` re-reads the platform window and silently reverts the override to 2.0. ## Solution - Back the value with `TestWindowState`, still defaulting to `2.0`, so existing tests are unchanged. - Add `TestWindow::simulate_scale_factor_change`, which stores the new factor and reports it through the resize callback — the same channel a real DPI change reaches the window on — plus the matching wrappers on `TestAppContext`, `VisualTestContext`, and `TestAppWindow`, mirroring the `simulate_resize` family. - Because the platform window owns the value, it survives later bounds changes (unlike `set_scale_factor`); the test pins that. ## Testing - Added `test_simulate_scale_factor_change` in `crates/gpui/src/window.rs`: asserts the unchanged 2.0 default, that a simulated change propagates to `Window::scale_factor()` through the resize callback, and that it persists across a subsequent `simulate_resize`. - Reverting `scale_factor()` to the hardcoded `2.0` while keeping the test reproduces the failure (see Showcase), so the test pins the behaviour rather than passing vacuously. - `cargo test -p gpui --lib` — 299 passed, 0 failed: ``` running 299 tests ... test window::tests::test_simulate_scale_factor_change ... ok ... test result: ok. 299 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.23s ``` - Tested on macOS. The change is confined to test-support code (`platform/test/`, test contexts), which is platform independent, but I have not built the Linux or Windows platform crates. ## Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [ ] Unsafe blocks (if any) have justifying comments - [ ] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable ## Showcase Before — the new test against the hardcoded `2.0`: ``` thread 'window::tests::test_simulate_scale_factor_change' panicked at crates/gpui/src/window.rs:7230:9: assertion `left == right` failed left: 2.0 right: 1.0 test result: FAILED. 0 passed; 1 failed ``` After — see the full run above. Release Notes: - N/A --------- Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>
Zed
Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.
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