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`prefers-contrast`, `prefers-reduced-transparency` and `inverted-colors` are never measured, though `AccessibilityInfo` reports each

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Évaluation

Difficulté
3/5
Temps estimé
1-2 jours
Accessibilité débutants
68/100
Type d'issue
Bug
Clarté
Clairement spécifiée
Activité
Active
Stack technique
react-native, typescript
Domaine
accessibility, frontend

Piste de recherche

Start with src/native/conditions/media-query.ts and the reduced motion handling referenced by issue #388. Check how AccessibilityInfo exposes the three preference values and change events, then add focused tests alongside the reported reproducer at src/__tests__/native/accessibility-preferences.test.tsx. Done means the three media features match their enabled values and respond to preference changes.

Rédigé par le modèle d'indexation à partir du texte de l'issue.

Description

Before submitting a new issue
  • I tested using the latest version of the library, as the bug might be already fixed.
  • I tested using a supported version of react native.
  • I checked for possible duplicate issues, with possible answers.
Bug summary

The media evaluator answers prefers-color-scheme, and with #388 prefers-reduced-motion, but no other user preference, though React Native 0.86's AccessibilityInfo reports three more, each with a change event:

  • prefers-contrast: more: isDarkerSystemColorsEnabled() on iOS (Increase Contrast) and isHighTextContrastEnabled() on Android;
  • prefers-reduced-transparency: reduce: isReduceTransparencyEnabled() on iOS, which Android resolves false;
  • inverted-colors: inverted: isInvertColorsEnabled() on both.

getMediaFeatureValue (src/native/conditions/media-query.ts) has no arm for them, so (prefers-contrast: more) never matches for someone who turned contrast up, and not (prefers-contrast: more) matches for everyone. With no preference set, Chromium 156, Firefox 157 and WebKit 27.2 answer prefers-contrast with no-preference; Chromium alone also answers prefers-reduced-transparency, and WebKit alone inverted-colors.

condition the engines that answer it main (2421ea7) #426 (40bfda2)
(prefers-contrast: no-preference) match (all three) no match no match
not (prefers-contrast: more) match (all three) match no match
(prefers-reduced-transparency: no-preference) match (Chromium) no match no match
(inverted-colors: none) match (WebKit) no match no match

#426 answers an unmeasured feature unknown (MQ5 §3.1), so there not (prefers-contrast: more) stops matching too, and lists these three among its known limits. Each can follow #388, which reads isReduceMotionEnabled() and reduceMotionChanged.

Library version

main at 2421ea7 (0.0.0-nightly.2421ea7)

Environment info
System:
  OS: Windows 11 10.0.26300
  CPU: "(32) x64 AMD Ryzen 9 9950X3D 16-Core Processor          "
  Memory: 155.26 GB / 255.67 GB
Binaries:
  Node:
    version: 26.12.1
    path: C:\Program Files\nodejs\node.EXE
  Yarn:
    version: 4.9.2
    path: C:\Users\<user>\AppData\Roaming\npm\yarn.CMD
  npm:
    version: 12.2.1
    path: C:\Program Files\nodejs\npm.CMD
  Watchman: Not Found
SDKs:
  Android SDK:
    API Levels:
      - "33"
      - "35"
      - "35"
      - "35"
      - "36"
      - "37"
    Build Tools:
      - 35.0.0
      - 36.0.0
      - 36.1.0
      - 37.0.0
    System Images:
      - android-26 | Google APIs Intel x86_64 Atom
      - android-28 | Google APIs Intel x86_64 Atom
      - android-29 | Google APIs Intel x86_64 Atom
      - android-30 | Google APIs Intel x86_64 Atom
      - android-31 | Google APIs Intel x86_64 Atom
      - android-32 | Google APIs Intel x86_64 Atom
      - android-33 | Google APIs Intel x86_64 Atom
      - android-34 | Google APIs Intel x86_64 Atom
      - android-35 | Google APIs Intel x86_64 Atom
      - android-36.1 | Google Play Intel x86_64 Atom
      - android-36.1 | Pre-Release 16 KB Page Size Google Play Intel x86_64 Atom
      - android-37.0 | Google APIs Intel x86_64 Atom
    Android NDK: Not Found
  Windows SDK: Not Found
IDEs:
  Android Studio: AI-262.9437.185.2621.16467767
  Visual Studio: Not Found
Languages:
  Java:
    version: 17.0.20.1
    path: C:\Program Files\Microsoft\jdk-17.0.20.101-hotspot\bin\javac.EXE
  Ruby: Not Found
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.86.3
    wanted: 0.86.3
  react-native-windows: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found
Steps to reproduce
  1. Clone the reproducer branch, which is main at 2421ea7 with one file added, src/__tests__/native/accessibility-preferences.test.tsx, and install: 
    git clone --branch repro/514-accessibility-preferences-unmeasured https://github.com/YevheniiKotyrlo/react-native-css
cd react-native-css
yarn install
  2. Run yarn jest src/__tests__/native/accessibility-preferences.test.tsx.

src/__tests__/native/accessibility-preferences.test.tsx:

// With no accessibility preference set, Chromium, Firefox and WebKit answer prefers-contrast no-preference, and WebKit inverted-colors none
import { render, screen } from "@testing-library/react-native";
import { View } from "react-native-css/components/View";
import { registerCSS } from "react-native-css/jest";

test.each([
  ["(prefers-contrast: no-preference)", true],
  ["not (prefers-contrast: more)", true],
  ["(prefers-reduced-transparency: no-preference)", true],
  ["(inverted-colors: none)", true],
])("with no preference set, @media %s matches: %s", (condition, expected) => {
  registerCSS(`
    .child { width: 10px; }
    @media ${condition} { .child { width: 37px; } }
  `);
  render(<View testID="child" className="child" />);
  expect(screen.getByTestId("child").props.style.width === 37).toBe(expected);
});

Expected: (prefers-contrast: more), (prefers-reduced-transparency: reduce) and (inverted-colors: inverted) match while AccessibilityInfo reports the setting on, and follow its change events.

Actual: none of them ever matches.

The run's output on main at 2421ea7, Windows 11, Node 26.12.1 
FAIL src/__tests__/native/accessibility-preferences.test.tsx
  × with no preference set, @media (prefers-contrast: no-preference) matches: true (20 ms)
  √ with no preference set, @media not (prefers-contrast: more) matches: true (6 ms)
  × with no preference set, @media (prefers-reduced-transparency: no-preference) matches: true (2 ms)
  × with no preference set, @media (inverted-colors: none) matches: true (1 ms)
  ● with no preference set, @media (prefers-contrast: no-preference) matches: true
    expect(received).toBe(expected) // Object.is equality
    Expected: true
    Received: false
      15 |   `);
      16 |   render(<View testID="child" className="child" />);
    > 17 |   expect(screen.getByTestId("child").props.style.width === 37).toBe(expected);
         |                                                                ^
      18 | });
      19 |
      at toBe (src/__tests__/native/accessibility-preferences.test.tsx:17:64)
  ● with no preference set, @media (prefers-reduced-transparency: no-preference) matches: true
    expect(received).toBe(expected) // Object.is equality
    Expected: true
    Received: false
      15 |   `);
      16 |   render(<View testID="child" className="child" />);
    > 17 |   expect(screen.getByTestId("child").props.style.width === 37).toBe(expected);
         |                                                                ^
      18 | });
      19 |
      at toBe (src/__tests__/native/accessibility-preferences.test.tsx:17:64)
  ● with no preference set, @media (inverted-colors: none) matches: true
    expect(received).toBe(expected) // Object.is equality
    Expected: true
    Received: false
      15 |   `);
      16 |   render(<View testID="child" className="child" />);
    > 17 |   expect(screen.getByTestId("child").props.style.width === 37).toBe(expected);
         |                                                                ^
      18 | });
      19 |
      at toBe (src/__tests__/native/accessibility-preferences.test.tsx:17:64)
Test Suites: 1 failed, 1 total
Tests:       3 failed, 1 passed, 4 total
Snapshots:   0 total
Time:        1.086 s, estimated 2 s
Ran all test suites matching /src\\__tests__\\native\\accessibility-preferences.test.tsx/i.
Reproducible example repository

https://github.com/YevheniiKotyrlo/react-native-css/tree/repro/514-accessibility-preferences-unmeasured

Langage dominant
TypeScript
Étoiles
166
Forks
45
Merge moyen
13 j 14 h
PR mergées (30 j)
1

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