Add non-regression test for processBooleanNotSureConditionalTypes trivially-true skip

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-10055.php

@@ -55,3 +55,30 @@ function testTriviallyTrueConditionSkipped(array $aggregation, string $type): vo
 
 	assertType('non-falsy-string', $type);
 }
+
+/**
+ * Non-regression test for TypeSpecifier::processBooleanNotSureConditionalTypes
+ * skipping trivially-always-true conditions.
+ *
+ * Without the fix, the BooleanAnd handler creates spurious conditional
+ * expressions like "$type=non-falsy-string => $value=string" because
+ * TypeCombinator::intersect(non-falsy-string, string) returns
+ * non-falsy-string unchanged (is_string() on a non-falsy-string is
+ * trivially always true). The spurious holder then fires inside
+ * if ($type !== 'filter') and incorrectly narrows $value to string.
+ *
+ * @param non-falsy-string $type
+ * @param int|string $value
+ */
+function testNotSureTriviallyTrueConditionSkipped(string $type, int|string $value): void
+{
+	if (is_string($type) && is_int($value)) {
+		return;
+	}
+
+	if ($type !== 'filter') {
+		assertType('int|string', $value);
+	}
+
+	assertType('non-falsy-string', $type);
+}