Return given filter from install()

Author: thekid

src/main/php/web/Application.class.php

@@ -62,7 +62,7 @@ public abstract function routes();
    * Installs global filters
    *
    * @param  web.Filter|function(web.Request, web.Response, web.filters.Invocation): var|web.Filter[] $arg
-   * @return void
+   * @return web.Filter|function(web.Request, web.Response, web.filters.Invocation): var|web.Filter[]
    */
   public function install($arg) {
     if ($arg instanceof Filter || $arg instanceof Closure) {
@@ -72,6 +72,7 @@ public function install($arg) {
         $this->filters[]= $filter;
       }
     }
+    return $arg;
   }
 
   /**

src/test/php/web/unittest/ApplicationTest.class.php

@@ -290,6 +290,14 @@ public function does_not_equal_clone() {
     Assert::equals(1, $app->compareTo(clone $app));
   }
 
+  #[Test, Values(from: 'filters')]
+  public function install($install) {
+    $app= new class($this->environment) extends Application {
+      public function routes() { /* Implementation irrelevant for this test */ }
+    };
+    Assert::equals($install, $app->install($install));
+  }
+
   #[Test, Values(from: 'filters')]
   public function install_filter($install) {
     list($request, $response)= $this->handle(function() use($install) {