[13.x] Fix Str::unwrap() to only strip when both sides match

[sumaiazaman]

Summary

Str::unwrap() currently strips the $before and $after strings independently. This means it mutates strings where only one side matches, which is unexpected — unwrap should be the strict inverse of wrap.

Context

Input	Before	After
'"value"' unwrap '"'	✅ 'value'	✅ 'value'
'"value' unwrap '"' (only start matches)	❌ 'value' (partial strip)	✅ '"value' (unchanged)
'value"' unwrap '"' (only end matches)	❌ 'value' (partial strip)	✅ 'value"' (unchanged)
'foo-bar-baz' unwrap 'foo-', '-baz'	✅ 'bar'	✅ 'bar'
'foo-bar' unwrap 'foo-', '-baz' (only start matches)	❌ 'bar' (partial strip)	✅ 'foo-bar' (unchanged)

Solution

Require both startsWith($before) and endsWith($after) to be true before stripping either end:

// Before
public static function unwrap($value, $before, $after = null)
{
    if (static::startsWith($value, $before)) {
        $value = static::substr($value, static::length($before));
    }

    if (static::endsWith($value, $after ??= $before)) {
        $value = static::substr($value, 0, -static::length($after));
    }

    return $value;
}

// After
public static function unwrap($value, $before, $after = null)
{
    $after ??= $before;

    if (static::startsWith($value, $before) && static::endsWith($value, $after)) {
        $value = static::substr($value, static::length($before));

        if ($after !== '') {
            $value = static::substr($value, 0, -static::length($after));
        }
    }

    return $value;
}

Safety

All existing fully-wrapped cases continue to work identically. The only behavioral change is for partially-wrapped strings, which now return the original value instead of silently stripping one end.

Changes

• src/Illuminate/Support/Str.php — fix unwrap() to require both sides to match
• tests/Support/SupportStrTest.php — update assertions for partial-wrap cases and add new assertions

Test Plan

• php vendor/bin/phpunit tests/Support/SupportStrTest.php --filter testUnwrap — passes
• php vendor/bin/phpunit tests/Support/SupportStringableTest.php --filter testUnwrap — passes

[taylorotwell]

Breaking change.

[sumaiazaman]

Breaking change.

Thanks for the feedback.