feat(wpmc S4): Helpers::main_town_slug reads ACF option

includes/class-helpers.php

@@ -99,4 +99,16 @@ final class Helpers
         $fragment = isset($parsed['fragment']) ? '#' . $parsed['fragment'] : '';
         return $path . $query . $fragment;
     }
+
+    public static function main_town_slug(): ?string
+    {
+        if (!\function_exists('get_field')) {
+            return null;
+        }
+        $value = \get_field('main_town_slug', 'option');
+        if ($value instanceof \WP_Term) {
+            return $value->slug !== '' ? $value->slug : null;
+        }
+        return is_string($value) && $value !== '' ? $value : null;
+    }
 }

tests/HelpersTest.php

@@ -211,4 +211,24 @@ final class HelpersTest extends TestCase
         // remove_domain_link is pure (no WP function dependencies) — exercise the proxy.
         self::assertSame('/foo/', wpmc_remove_domain_link('https://site.com/foo/'));
     }
+
+    public function test_main_town_slug_reads_option_via_acf(): void
+    {
+        \Brain\Monkey\Functions\expect('get_field')
+            ->once()
+            ->with('main_town_slug', 'option')
+            ->andReturn('spb');
+
+        self::assertSame('spb', Helpers::main_town_slug());
+    }
+
+    public function test_main_town_slug_returns_null_when_option_empty(): void
+    {
+        \Brain\Monkey\Functions\expect('get_field')
+            ->once()
+            ->with('main_town_slug', 'option')
+            ->andReturn(false);
+
+        self::assertNull(Helpers::main_town_slug());
+    }
 }