feat: comprehensive Docker PHPT test infrastructure and BCMath improvements

.github/workflows/ci.yml

@@ -94,7 +94,9 @@ jobs:
             -   name: Build Docker test image
                 run: docker build -f Dockerfile.test-without-bcmath --build-arg PHP_VERSION=${{ matrix.php-version }} -t bcmath-phpt-test:${{ matrix.php-version }} .
             -   name: Run Docker-based PHPT tests
-                run: docker run --rm -v $PWD:/app bcmath-phpt-test:${{ matrix.php-version }} --skip bcceil,bccomp,bcdivmod,bcfloor,bcmod,bcpow,bcpowmod,bcround,bcscale,bug54598,bug72093,bug75178,gh15968,gh16262,scale_ini,str2num_formatting,bcmul_check_overflow,bug78878,bccomp_variation001,bccomp_variation002,bcdivmod_by_zero,bcmod_error2,bcpow_div_by_zero,bcpow_error1,bcpow_error2,bcpow_error3,bcpow_large_numbers,bcpow_zero,bcpowmod_error,bcpowmod_with_mod_1,bcpowmod_zero_modulus,bcround_all,bcround_away_from_zero,bcround_ceiling,bcround_early_return,bcround_floor,bcround_half_down,bcround_toward_zero,bcscale_variation003
+                run: |
+                  # scale_ini test skipped: bcmath.scale INI setting ignored without native extension
+                  docker run --rm -v $PWD:/app bcmath-phpt-test:${{ matrix.php-version }} --skip bcdivmod,bug54598,bug72093,bug75178,gh15968,gh16262,scale_ini,bcmul_check_overflow,bug78878,bcpow_error1,bcpow_error2,bcpow_error3,bcpowmod_error,bcpowmod_with_mod_1,bcpowmod_zero_modulus,bcround_all,bcround_away_from_zero,bcround_ceiling,bcround_early_return,bcround_floor,bcround_toward_zero,bcscale_variation003,bcdivmod_by_zero
         strategy:
             fail-fast: false
             matrix:

README.md

@@ -99,8 +99,12 @@ This polyfill uses [phpseclib](https://github.com/phpseclib/phpseclib)'s BigInte
 - Recommended approach: Don't check for the extension, just use the functions
 
 ### Configuration Options
-- `ini_set('bcmath.scale', ...)` won't work without the native extension
-- Use `bcscale()` instead to set the scale globally
+- **bcmath.scale INI setting is ignored**: When the native bcmath extension is not loaded, PHP does not recognize the `bcmath.scale` INI setting. This means:
+  - `ini_get('bcmath.scale')` returns `false`
+  - `ini_set('bcmath.scale', ...)` won't work
+  - INI settings in php.ini or PHPT tests are ignored
+  - The polyfill defaults to scale 0 when no explicit scale is provided
+- **Workaround**: Use `bcscale()` instead to set the scale globally
 - To get the current scale:
   - PHP >= 7.3.0: Use `bcscale()` without arguments
   - PHP < 7.3.0: Use `max(0, strlen(bcadd('0', '0')) - 2)`

lib/RoundingMode.php

@@ -4,7 +4,7 @@
  * RoundingMode enum polyfill for PHP 8.1-8.3.
  *
  * This enum provides the same interface as PHP 8.4's native RoundingMode enum,
- * but TowardsZero, AwayFromZero, and NegativeInfinity will throw exceptions
+ * but TowardsZero, AwayFromZero, NegativeInfinity, and PositiveInfinity will throw exceptions
  * when used in PHP < 8.4 to maintain compatibility expectations.
  *
  * The enum is only defined if:
@@ -22,5 +22,6 @@ enum RoundingMode: string
         case TowardsZero = 'towards_zero';
         case AwayFromZero = 'away_from_zero';
         case NegativeInfinity = 'negative_infinity';
+        case PositiveInfinity = 'positive_infinity';
     }
 }