LibWeb: Add a simple internals objects only available during testing

This object is available as `window.internals` (or just `internals`) and
is only accessible while running in "test mode".

This first version only has one API: gc(), which triggers a garbage
collection immediately.

In the future, we can add more APIs here to help us test parts of the
engine that are hard or impossible to reach via public web APIs.

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -397,6 +397,7 @@ set(SOURCES
     Infra/ByteSequences.cpp
     Infra/JSON.cpp
     Infra/Strings.cpp
+    Internals/Internals.cpp
     IntersectionObserver/IntersectionObserver.cpp
     IntersectionObserver/IntersectionObserverEntry.cpp
     Layout/AudioBox.cpp

Userland/Libraries/LibWeb/Forward.h

@@ -454,6 +454,10 @@ namespace Web::HighResolutionTime {
 class Performance;
 }
 
+namespace Web::Internals {
+class Internals;
+}
+
 namespace Web::IntersectionObserver {
 class IntersectionObserver;
 class IntersectionObserverEntry;

Userland/Libraries/LibWeb/HTML/Window.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2023, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2021-2022, Sam Atkins <atkinssj@serenityos.org>
  * Copyright (c) 2021-2023, Linus Groh <linusg@serenityos.org>
  *
@@ -51,6 +51,7 @@
 #include <LibWeb/HighResolutionTime/TimeOrigin.h>
 #include <LibWeb/Infra/Base64.h>
 #include <LibWeb/Infra/CharacterTypes.h>
+#include <LibWeb/Internals/Internals.h>
 #include <LibWeb/Layout/Viewport.h>
 #include <LibWeb/Page/Page.h>
 #include <LibWeb/RequestIdleCallback/IdleDeadline.h>
@@ -805,6 +806,13 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::CallbackType>> Window::byte_length_
     return JS::NonnullGCPtr { *m_byte_length_queuing_strategy_size_function };
 }
 
+static bool s_internals_object_exposed = false;
+
+void Window::set_internals_object_exposed(bool exposed)
+{
+    s_internals_object_exposed = exposed;
+}
+
 WebIDL::ExceptionOr<void> Window::initialize_web_interfaces(Badge<WindowEnvironmentSettingsObject>)
 {
     auto& realm = this->realm();
@@ -815,6 +823,9 @@ WebIDL::ExceptionOr<void> Window::initialize_web_interfaces(Badge<WindowEnvironm
     MUST_OR_THROW_OOM(Bindings::WindowGlobalMixin::initialize(realm, *this));
     MUST_OR_THROW_OOM(WindowOrWorkerGlobalScopeMixin::initialize(realm));
 
+    if (s_internals_object_exposed)
+        define_direct_property("internals", MUST_OR_THROW_OOM(heap().allocate<Internals::Internals>(realm, realm)), JS::default_attributes);
+
     return {};
 }
 

Userland/Libraries/LibWeb/HTML/Window.h

@@ -190,6 +190,8 @@ public:
     HighResolutionTime::DOMHighResTimeStamp get_last_activation_timestamp() const { return m_last_activation_timestamp; }
     void set_last_activation_timestamp(HighResolutionTime::DOMHighResTimeStamp timestamp) { m_last_activation_timestamp = timestamp; }
 
+    static void set_internals_object_exposed(bool);
+
 private:
     explicit Window(JS::Realm&);
 

Userland/Libraries/LibWeb/Internals/Internals.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/VM.h>
+#include <LibWeb/Bindings/InternalsPrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Internals/Internals.h>
+
+namespace Web::Internals {
+
+Internals::Internals(JS::Realm& realm)
+    : Bindings::PlatformObject(realm)
+{
+}
+
+Internals::~Internals() = default;
+
+JS::ThrowCompletionOr<void> Internals::initialize(JS::Realm& realm)
+{
+    TRY(Base::initialize(realm));
+    Object::set_prototype(&Bindings::ensure_web_prototype<Bindings::InternalsPrototype>(realm, "Internals"));
+    return {};
+}
+
+void Internals::gc()
+{
+    vm().heap().collect_garbage();
+}
+
+}

Userland/Libraries/LibWeb/Internals/Internals.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Bindings/PlatformObject.h>
+
+namespace Web::Internals {
+
+class Internals final : public Bindings::PlatformObject {
+    WEB_PLATFORM_OBJECT(Internals, Bindings::PlatformObject);
+
+public:
+    virtual ~Internals() override;
+
+    void gc();
+
+private:
+    explicit Internals(JS::Realm&);
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
+};
+
+}

Userland/Libraries/LibWeb/Internals/Internals.idl

@@ -0,0 +1,5 @@
+[Exposed=Nobody] interface Internals {
+
+    undefined gc();
+
+};

Userland/Libraries/LibWeb/idl_files.cmake

@@ -183,6 +183,7 @@ libweb_js_bindings(HTML/WorkerGlobalScope)
 libweb_js_bindings(HTML/WorkerLocation)
 libweb_js_bindings(HTML/WorkerNavigator)
 libweb_js_bindings(HighResolutionTime/Performance)
+libweb_js_bindings(Internals/Internals)
 libweb_js_bindings(IntersectionObserver/IntersectionObserver)
 libweb_js_bindings(IntersectionObserver/IntersectionObserverEntry)
 libweb_js_bindings(NavigationTiming/PerformanceTiming)