test(api): drop deprecated shims from coverage; test the null-query path

The deprecated global function shims are guarded by function_exists() checks that execute during Composer's files autoload -- before PHPUnit starts collecting coverage -- so those lines can never be covered. Wrap the back-compat block in @codeCoverageIgnore; the shim bodies are still exercised by PublicApiTest.

Also add a test for get_page_id_for_custom_post_type() called with no post type outside a PFCPT query (the query-var fallthrough). functions.php goes 78% -> 93%.

Author: nlemoine

src/functions.php

@@ -73,6 +73,10 @@ function get_page_url_for_custom_post_type(?string $postType = null): ?string
 }
 
 namespace {
+    // Deprecated back-compat shims. The function_exists() guards run during
+    // Composer's files autoload, before coverage starts, so they cannot be
+    // covered; the function bodies are exercised by PublicApiTest.
+    // @codeCoverageIgnoreStart
     if (!\function_exists('is_page_for_custom_post_type')) {
         /**
          * @deprecated 1.0.0 Use \n5s\PageForCustomPostType\is_page_for_custom_post_type() instead.
@@ -124,4 +128,5 @@ function get_page_url_for_custom_post_type(?string $postType = null): ?string
             return \n5s\PageForCustomPostType\get_page_url_for_custom_post_type($postType);
         }
     }
+    // @codeCoverageIgnoreEnd
 }

tests/Integration/PublicApiTest.php

@@ -97,6 +97,14 @@ public function testGetPageIdForCustomPostTypeUsesCurrentQueryWhenNull(): void
         );
     }
 
+    public function testGetPageIdForCustomPostTypeReturnsNullOnRegularPage(): void
+    {
+        $this->setExpectedDeprecated('get_page_id_for_custom_post_type');
+        $this->get(get_permalink($this->staticFrontPageId));
+
+        $this->assertNull(get_page_id_for_custom_post_type());
+    }
+
     public function testGetPageUrlForCustomPostTypeReturnsUrl(): void
     {
         $this->setExpectedDeprecated('get_page_url_for_custom_post_type');