Create a new type of mock compositor for client tests

There are a number of issues with the current client testing:

- Adding new compositor functionality is cumbersome (need to add compositor
  send method, command, implementation, not to mention creating new wrapper
  objects.
- Customizing available globals and their versions is not possible and would be
  hard to implement. I.e. how to test that functionality works with old and new
  versions of an interface? Handle globals being destroyed. We did this with
  wl_output, but it was painfully cumbersome.
- Hard to verify that the compositor state is clean between tests. It is
  currently done in some tests, but requires boiler plate code which needs to
  be added and maintained for each test.
- In general lots of boiler-plate for new tests. (We have to have separate
  tests as long as Qt has global/static state. I.e. if one shell extension has
  been initialized, we can't deinitialize and initialize another one, so tests
  have to be separate.)
- Dispatching server events tied to the client event loop sometimes makes it
  hard to write tests without deadlocks.
- Abstraction, encapsulation and automatic behavior that can't be disabled
  makes it hard to test low-level functionality like surface exposure.

So, in an attempt to mitigate these issues, I wrote a new testing framework.

- Compositor dispatch is running continuously in it's own thread, access to
  compositor state is guarded by a mutex on the compositor, locking this will
  make dispatching stop, so the test can safely access internals. Although a
  bit cumbersome at first this makes it much easier to directly use server
  protocol commands from the test itself, i.e. no need to create commands for
  every single thing we want to test.
- The CoreCompositor::exec template method can accept a lambda that will be run
  with dispatching stopped. It can also return a value, conveniently letting us
  safely extract or modify compositor state from tests.
- This framework also takes full advantage of the qtwaylandscanner, using
  wrapper classes for everything, reducing boiler plate considerably.
- The compositor parts are designed to do as little as possible automatically,
  but still provide easy ways to enable common functionality, like releasing
  buffers automatically, configuring shell surfaces etc.
- Compositor globals are pluggable, use add<GlobalClass>() and
  remove<GlobalClass>() to add new global interfaces. I.e. easy to create a
  compositor with or without data_device_manager for instance.
- DefaultCompositor provides a sensible default set of functionality and
  convenience methods for most test-cases. Custom ones can still be made by
  inheriting from CoreCompositor directly instead or by removing or adding
  globals to DefaultCompositor.
- Globals have an isClean() method. Implement it to verify that the client
  didn't leave any objects lying around from the previous test.
  CoreCompositor::isClean calls isClean on the globals so a single call is all
  that's needed.

In short, we've traded mock compositor encapsulation and thread safety
guarantees for less boiler-plate, easier and more convenient access to
internals.

Anything accessing compositor state should go into a exec() call, or through
the wrapper macros QCOMPOSITOR_VERIFY and QCOMPOSITOR_COMPARE (or the TRY
versions). I've also tried to make the compositor print warnings if compositor
state is accessed in an unsafe way.

The mock compositor is currently built once per test due to CI limitations
(same thing as with the old tests).

Change-Id: Ia3feb80ce175d3814292b7f4768a0cc719f8b0e8
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 209 insertions, 0 deletions

diff --git a/tests/auto/client/shared/corecompositor.h b/tests/auto/client/shared/corecompositor.h
new file mode 100644
index 000000000..875b7d050
--- /dev/null
+++ b/tests/auto/client/shared/corecompositor.h
@@ -0,0 +1,209 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef MOCKCOMPOSITOR_CORECOMPOSITOR_H
+#define MOCKCOMPOSITOR_CORECOMPOSITOR_H
+
+#include <QtTest/QtTest>
+
+#include <wayland-server-core.h>
+
+struct wl_resource;
+
+namespace MockCompositor {
+
+class Global : public QObject
+{
+    Q_OBJECT
+public:
+    virtual bool isClean() { return true; }
+    virtual QString dirtyMessage() { return isClean() ? "clean" : "dirty"; }
+};
+
+class CoreCompositor
+{
+public:
+    explicit CoreCompositor();
+    ~CoreCompositor();
+    bool isClean();
+    QString dirtyMessage();
+    void dispatch();
+
+    template<typename function_type, typename... arg_types>
+    auto exec(function_type func, arg_types&&... args) -> decltype(func())
+    {
+        Lock lock(this);
+        return func(std::forward<arg_types>(args)...);
+    }
+
+    template<typename function_type, typename... arg_types>
+    auto call(function_type func, arg_types&&... args) -> decltype(func())
+    {
+        Lock lock(this);
+        auto boundFunc = std::bind(func, this);
+        return boundFunc(this, std::forward<arg_types>(args)...);
+    }
+
+    // Unsafe section below, YOU are responsible that the compositor is locked or
+    // this is run through the mutex() method!
+
+    void add(Global *global);
+    void remove(Global *global);
+
+    /*!
+     * \brief Constructs and adds a new global with the given parameters
+     *
+     * Convenience function. i.e.
+     *
+     *     compositor->add(new MyGlobal(compositor, version);
+     *
+     * can be written as:
+     *
+     *     compositor->add<MyGlobal>(version);
+     *
+     * Returns the new global
+     */
+    template<typename global_type, typename... arg_types>
+    global_type *add(arg_types&&... args)
+    {
+        warnIfNotLockedByThread(Q_FUNC_INFO);
+        auto *global = new global_type(this, std::forward<arg_types>(args)...);
+        m_globals.append(global);
+        return global;
+    }
+
+    /*!
+     * \brief Removes all globals of the given type
+     *
+     * Convenience function
+     */
+    template<typename global_type, typename... arg_types>
+    void removeAll()
+    {
+        const auto globals = getAll<global_type>();
+        for (auto global : globals)
+            remove(global);
+    }
+
+    /*!
+     * \brief Returns a global with the given type, if any
+     */
+    template<typename global_type>
+    global_type *get()
+    {
+        warnIfNotLockedByThread(Q_FUNC_INFO);
+        for (auto *global : qAsConst(m_globals)) {
+            if (auto *casted = qobject_cast<global_type *>(global))
+                return casted;
+        }
+        return nullptr;
+    }
+
+    /*!
+     * \brief Returns all globals with the given type, if any
+     */
+    template<typename global_type>
+    QVector<global_type *> getAll()
+    {
+        warnIfNotLockedByThread(Q_FUNC_INFO);
+        QVector<global_type *> matching;
+        for (auto *global : qAsConst(m_globals)) {
+            if (auto *casted = qobject_cast<global_type *>(global))
+                matching.append(casted);
+        }
+        return matching;
+    }
+
+    uint nextSerial();
+    uint currentTimeMilliseconds();
+    wl_client *client(int index = 0);
+    void warnIfNotLockedByThread(const char* caller = "warnIfNotLockedbyThread");
+
+public:
+    // Only use this carefully from the test thread (i.e. lock first)
+    wl_display *m_display = nullptr;
+protected:
+    class Lock {
+    public:
+        explicit Lock(CoreCompositor *compositor)
+            : m_compositor(compositor)
+            , m_threadId(std::this_thread::get_id())
+        {
+            // Can't use a QMutexLocker here, as it's not movable
+            compositor->m_mutex.lock();
+            Q_ASSERT(compositor->m_lock == nullptr);
+            compositor->m_lock = this;
+        }
+        ~Lock()
+        {
+            Q_ASSERT(m_compositor->m_lock == this);
+            m_compositor->m_lock = nullptr;
+            m_compositor->m_mutex.unlock();
+        }
+
+        // Move semantics
+        Lock(Lock &&) = default;
+        Lock &operator=(Lock &&) = default;
+
+        // Disable copying
+        Lock(const Lock &) = delete;
+        Lock &operator=(const Lock &) = delete;
+
+        bool isOwnedByCurrentThread() const { return m_threadId == std::this_thread::get_id(); }
+    private:
+        CoreCompositor *m_compositor = nullptr;
+        std::thread::id m_threadId;
+    };
+    QByteArray m_socketName;
+    wl_event_loop *m_eventLoop = nullptr;
+    bool m_running = true;
+    QVector<Global *> m_globals;
+    QElapsedTimer m_timer;
+
+private:
+    Lock *m_lock = nullptr;
+    QMutex m_mutex;
+    std::thread m_dispatchThread;
+};
+
+template<typename container_type>
+QByteArray toByteArray(container_type container)
+{
+    return QByteArray(reinterpret_cast<const char *>(container.data()), sizeof (container[0]) * container.size());
+}
+
+template<typename return_type>
+return_type *fromResource(::wl_resource *resource) {
+    if (auto *r = return_type::Resource::fromResource(resource))
+        return static_cast<return_type *>(r->object());
+    return nullptr;
+}
+
+} // namespace MockCompositor
+
+#endif // MOCKCOMPOSITOR_CORECOMPOSITOR_H