Add localTitle function with Test for 'en' and 'nl'

src/core/etl/src/Flow/ETL/Function/ScalarFunctionChain.php

@@ -487,6 +487,11 @@ public function stringFold() : self
         return new StringFold($this);
     }
 
+    public function stringLocaleTitle(ScalarFunction|string $locale) : self
+    {
+        return new StringLocaleTitle($this, $locale);
+    }
+
     public function stringStyle(ScalarFunction|string|StringStyles $style) : self
     {
         return new StringStyle($this, $style);

src/core/etl/src/Flow/ETL/Function/StringLocaleTitle.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Function;
+
+use function Flow\ETL\DSL\type_string;
+use function Symfony\Component\String\u;
+use Flow\ETL\Function\ScalarFunction\TypedScalarFunction;
+use Flow\ETL\PHP\Type\Type;
+use Flow\ETL\Row;
+use Symfony\Component\String\AbstractUnicodeString;
+
+final class StringLocaleTitle extends ScalarFunctionChain implements TypedScalarFunction
+{
+    public function __construct(
+        private readonly ScalarFunction|string $string,
+        private readonly ScalarFunction|string $locale,
+    ) {
+    }
+
+    public function eval(Row $row) : mixed
+    {
+        $string = (new Parameter($this->string))->asString($row);
+        $locale = (new Parameter($this->locale))->asString($row);
+
+        if ($string === null || $locale === null) {
+            return null;
+        }
+
+        /** @phpstan-ignore-next-line */
+        if (!method_exists(AbstractUnicodeString::class, 'localeTitle')) {
+            return u($string)->title()->toString();
+        }
+
+        return u($string)->localeTitle($locale)->toString();
+    }
+
+    public function returns() : Type
+    {
+        return type_string();
+    }
+}

src/core/etl/tests/Flow/ETL/Tests/Unit/Function/StringLocaleTitleTest.php

@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Tests\Unit\Function;
+
+use function Flow\ETL\DSL\row;
+use function Flow\ETL\DSL\{ref, str_entry, type_string};
+use Flow\ETL\Function\StringLocaleTitle;
+use Flow\ETL\PHP\Type\Type;
+use Flow\ETL\Tests\FlowTestCase;
+use Symfony\Component\String\AbstractUnicodeString;
+
+final class StringLocaleTitleTest extends FlowTestCase
+{
+    public function test_returns_method_returns_string_type() : void
+    {
+        $stringTitleFunction = new StringLocaleTitle('str', 'en');
+        $returnType = $stringTitleFunction->returns();
+
+        self::assertInstanceOf(Type::class, $returnType);
+
+        self::assertTrue($returnType->isEqual(type_string()));
+    }
+
+    public function test_string_locale_title_en() : void
+    {
+        /** @phpstan-ignore-next-line */
+        if (method_exists(AbstractUnicodeString::class, 'localeTitle')) {
+            self::assertSame(
+                'Foo ijssel',
+                ref('str')->stringLocaleTitle('en')->eval(
+                    row(str_entry('str', 'foo ijssel'))
+                )
+            );
+        } else {
+            self::assertSame(
+                'Foo ijssel',
+                ref('str')->stringTitle()->eval(
+                    row(str_entry('str', 'foo ijssel'))
+                )
+            );
+        }
+    }
+
+    public function test_string_locale_title_nl() : void
+    {
+        /** @phpstan-ignore-next-line */
+        if (method_exists(AbstractUnicodeString::class, 'localeTitle')) {
+            self::assertSame(
+                'Foo IJssel',
+                ref('str')->stringLocaleTitle('nl')->eval(
+                    row(str_entry('str', 'foo ijssel'))
+                )
+            );
+        } else {
+            self::assertNotSame(
+                'Foo IJssel',
+                ref('str')->stringTitle()->eval(
+                    row(str_entry('str', 'foo ijssel'))
+                )
+            );
+        }
+
+    }
+}