Add resolver seam so the Throwable catch path is testable (WOOTAX-303)

The catch ( Throwable ) in StoreApiExtendSchema - the core WOOTAX-303 fix - had
no test because the container call was a hard-coded static inside a private
constructor with no injection point.

Extract the container resolution into a protected static resolve_extend_schema()
seam and instantiate via new static(), so a test double can override it to throw.
The constructor is now protected (external instantiation is still blocked). Behavior
is unchanged for the base class: new static() resolves to self there.

Add test_instance_returns_null_when_container_throws(), which drives a subclass
whose resolver throws a TypeError - a Throwable that is NOT an Exception, so it
would propagate (and fail the test) against the pre-fix catch ( Exception ). This
locks in the widening and asserts the failure is logged once.

Author: iyut

src/StoreApi/StoreApiExtendSchema.php

@@ -47,17 +47,32 @@ class StoreApiExtendSchema {
 
 	/**
 	 * ExtendSchemaService constructor.
+	 *
+	 * Protected rather than private so tests can subclass and override
+	 * resolve_extend_schema() to exercise the resolution-failure path.
 	 */
-	private function __construct() {
+	protected function __construct() {
 		self::$attempted = true;
 
 		try {
-			self::$instance = StoreApi::container()->get( ExtendSchema::class );
+			self::$instance = static::resolve_extend_schema();
 		} catch ( Throwable $e ) {
 			wc_get_logger()->debug( 'Failed to get ExtendSchema instance.', array( 'exception' => $e ) );
 		}
 	}
 
+	/**
+	 * Resolve the ExtendSchema instance from the Store API container.
+	 *
+	 * Extracted as a seam so a broken container can be simulated in tests (subclass
+	 * and override to throw) without needing a genuinely partial WooCommerce install.
+	 *
+	 * @return ExtendSchema
+	 */
+	protected static function resolve_extend_schema(): ExtendSchema {
+		return StoreApi::container()->get( ExtendSchema::class );
+	}
+
 	/**
 	 * Returns the ExtendSchema instance, or null when it cannot be resolved.
 	 *
@@ -67,7 +82,7 @@ private function __construct() {
 	 */
 	public static function instance(): ?ExtendSchema {
 		if ( ! self::$attempted ) {
-			new self();
+			new static();
 		}
 
 		return self::$instance;

tests/php/class-wcservices-throwing-store-api-extend-schema.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Test double for StoreApiExtendSchema that simulates container resolution failure.
+ *
+ * @package Automattic/WCServices
+ */
+
+// No direct access please.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+if ( ! class_exists( 'WCServices_Throwing_Store_Api_Extend_Schema' ) ) {
+
+	/**
+	 * Forces StoreApiExtendSchema's container resolution to fail with a TypeError, so the
+	 * catch ( Throwable ) path in instance() can be exercised without a broken WooCommerce
+	 * install (WOOTAX-303).
+	 */
+	class WCServices_Throwing_Store_Api_Extend_Schema extends \Automattic\WCServices\StoreApi\StoreApiExtendSchema {
+
+		// phpcs:disable Squiz.Commenting.FunctionComment.InvalidNoReturn -- Test double intentionally always throws to simulate a resolution failure.
+		/**
+		 * Simulate a container that cannot resolve ExtendSchema.
+		 *
+		 * @throws \TypeError Always, to mimic a container resolution failure.
+		 * @return \Automattic\WooCommerce\StoreApi\Schemas\ExtendSchema
+		 */
+		protected static function resolve_extend_schema(): \Automattic\WooCommerce\StoreApi\Schemas\ExtendSchema {
+			throw new \TypeError( 'Simulated container resolution failure.' );
+		}
+		// phpcs:enable Squiz.Commenting.FunctionComment.InvalidNoReturn
+	}
+}

tests/php/test-woocommerce-connect-client.php

@@ -1,5 +1,7 @@
 <?php
 
+require_once __DIR__ . '/class-wcservices-throwing-store-api-extend-schema.php';
+
 class WP_Test_WC_Connect_Loader extends WC_Unit_Test_Case {
 
 	const SERVICE_SCRIPT_HANDLE = 'wc_connect_admin';
@@ -470,4 +472,47 @@ public function test_instance_returns_cached_instance_without_reresolving() {
 			$instance->setValue( $orig_instance );
 		}
 	}
+
+	/**
+	 * When the container throws while resolving ExtendSchema, instance() must catch it
+	 * and return null instead of fataling. A TypeError is used deliberately: it is a
+	 * Throwable but not an Exception, so pre-fix code (catch Exception) would let it
+	 * propagate. The failure must also be logged once (WOOTAX-303).
+	 *
+	 * @testdox instance() returns null and logs when the container throws a non-Exception Throwable.
+	 * @covers Automattic\WCServices\StoreApi\StoreApiExtendSchema::instance
+	 */
+	public function test_instance_returns_null_when_container_throws() {
+		$class     = '\Automattic\WCServices\StoreApi\StoreApiExtendSchema';
+		$attempted = new ReflectionProperty( $class, 'attempted' );
+		$instance  = new ReflectionProperty( $class, 'instance' );
+		$attempted->setAccessible( true );
+		$instance->setAccessible( true );
+
+		$orig_attempted = $attempted->getValue();
+		$orig_instance  = $instance->getValue();
+
+		$logger = $this->getMockBuilder( 'WC_Logger_Interface' )->getMock();
+		$logger->expects( $this->once() )
+			->method( 'debug' )
+			->with( 'Failed to get ExtendSchema instance.', $this->anything() );
+
+		$inject_logger = function () use ( $logger ) {
+			return $logger;
+		};
+		add_filter( 'woocommerce_logging_class', $inject_logger );
+
+		try {
+			$attempted->setValue( false );
+			$instance->setValue( null );
+
+			$result = WCServices_Throwing_Store_Api_Extend_Schema::instance();
+
+			$this->assertNull( $result, 'instance() must return null - not fatal - when the container throws a non-Exception Throwable.' );
+		} finally {
+			remove_filter( 'woocommerce_logging_class', $inject_logger );
+			$attempted->setValue( $orig_attempted );
+			$instance->setValue( $orig_instance );
+		}
+	}
 }