A boolean prop's attribute reads as the strings `"false"` and `"true"`: `[disabled="false"]` matches `disabled={false}`, and `[disabled=""]` misses `disabled={true}`

Start with the reported reproducer, src/__tests__/native/plain-prop-attribute-model.test.tsx, and trace how plain props are projected into attribute selector matching. Run the listed Jest command to confirm the four cases. Done means false booleans do not match [disabled="false"], true booleans match [disabled=""], and the presence selector behavior remains correct.

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

A plain prop reaches attribute selectors through a model that disagrees with the DOM in two ways. [disabled] reads disabled={false} as an absent attribute, as React DOM removes it, but a value selector compares the same false as the string "false", so [disabled="false"] matches where an absent attribute matches no [att=val]. A true boolean prop is the string "true", where React DOM renders disabled={true} as the empty value, so [disabled="true"] matches and [disabled=""] does not, the reverse of Chromium.

The last three fail; [disabled] with disabled={false} passes.

Expected: the DOM's model, an absent attribute for false (and, as React DOM does, for a function or a symbol) and the empty value for true; or, if the library keeps its own, one model for presence and value alike.

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/plain-prop-attribute-model.test.tsx, and install:

   git clone --branch repro/542-prop-attribute-projection https://github.com/YevheniiKotyrlo/react-native-css
   cd react-native-css
   yarn install
   

2. Run yarn jest src/__tests__/native/plain-prop-attribute-model.test.tsx.

src/__tests__/native/plain-prop-attribute-model.test.tsx:

import { TextInput } from "react-native-css/components/TextInput";
import { render, screen } from "@testing-library/react-native";
import { registerCSS, testID } from "react-native-css/jest";

test.each([
  ["[disabled]", false, false],
  ['[disabled="false"]', false, false],
  ['[disabled="true"]', true, false],
  ['[disabled=""]', true, true],
])(".a%s with disabled={%s} matches: %s", (attribute, disabled, expected) => {
  registerCSS(`.a${attribute} { width: 37px; }`);
  render(<TextInput testID={testID} className="a" disabled={disabled} />);
  expect(screen.getByTestId(testID).props.style?.width === 37).toBe(expected);
});

Expected: attribute selectors read a boolean prop as React DOM renders it: [disabled="false"] matches no disabled={false}, and [disabled=""] matches disabled={true}.

Actual: [disabled="false"] matches disabled={false}, [disabled="true"] matches disabled={true}, and [disabled=""] misses it.

FAIL src/__tests__/native/plain-prop-attribute-model.test.tsx
  √ .a[disabled] with disabled={false} matches: false (16 ms)
  × .a[disabled="false"] with disabled={false} matches: false (5 ms)
  × .a[disabled="true"] with disabled={true} matches: false (1 ms)
  × .a[disabled=""] with disabled={true} matches: true (1 ms)
  ● .a[disabled="false"] with disabled={false} matches: false
    expect(received).toBe(expected) // Object.is equality
    Expected: false
    Received: true
      11 |   registerCSS(`.a${attribute} { width: 37px; }`);
      12 |   render(<TextInput testID={testID} className="a" disabled={disabled} />);
    > 13 |   expect(screen.getByTestId(testID).props.style?.width === 37).toBe(expected);
         |                                                                ^
      14 | });
      15 |
      at toBe (src/__tests__/native/plain-prop-attribute-model.test.tsx:13:64)
  ● .a[disabled="true"] with disabled={true} matches: false
    expect(received).toBe(expected) // Object.is equality
    Expected: false
    Received: true
      11 |   registerCSS(`.a${attribute} { width: 37px; }`);
      12 |   render(<TextInput testID={testID} className="a" disabled={disabled} />);
    > 13 |   expect(screen.getByTestId(testID).props.style?.width === 37).toBe(expected);
         |                                                                ^
      14 | });
      15 |
      at toBe (src/__tests__/native/plain-prop-attribute-model.test.tsx:13:64)
  ● .a[disabled=""] with disabled={true} matches: true
    expect(received).toBe(expected) // Object.is equality
    Expected: true
    Received: false
      11 |   registerCSS(`.a${attribute} { width: 37px; }`);
      12 |   render(<TextInput testID={testID} className="a" disabled={disabled} />);
    > 13 |   expect(screen.getByTestId(testID).props.style?.width === 37).toBe(expected);
         |                                                                ^
      14 | });
      15 |
      at toBe (src/__tests__/native/plain-prop-attribute-model.test.tsx:13:64)
Test Suites: 1 failed, 1 total
Tests:       3 failed, 1 passed, 4 total
Snapshots:   0 total
Time:        1.048 s, estimated 2 s
Ran all test suites matching /src\\__tests__\\native\\plain-prop-attribute-model.test.tsx/i.

Reproducible example repository

https://github.com/YevheniiKotyrlo/react-native-css/tree/repro/542-prop-attribute-projection