diff --git a/interfaces/iproject.h b/interfaces/iproject.h
--- a/interfaces/iproject.h
+++ b/interfaces/iproject.h
@@ -174,6 +174,9 @@
 public Q_SLOTS:
     /** Make the model to reload */
     virtual void reloadModel() = 0;
+
+    /** This method is invoked when the project needs to be closed. */
+    virtual void close() = 0;
 };
 
 }
diff --git a/interfaces/iprojectcontroller.h b/interfaces/iprojectcontroller.h
--- a/interfaces/iprojectcontroller.h
+++ b/interfaces/iprojectcontroller.h
@@ -141,6 +141,15 @@
      * @returns true if the project could be closed, false otherwise
      */
     virtual void closeProject( IProject* ) = 0;
+
+    /**
+     * Close all projects
+     *
+     * This usually calls closeProject() on all controlled projects
+     * @sa closeProject()
+     */
+    virtual void closeAllProjects() = 0;
+
     virtual void configureProject( IProject* ) = 0;
 
     /// Schedules all files of the @p project for reparsing by @see BackgroundParser
diff --git a/plugins/quickopen/tests/bench_quickopen.cpp b/plugins/quickopen/tests/bench_quickopen.cpp
--- a/plugins/quickopen/tests/bench_quickopen.cpp
+++ b/plugins/quickopen/tests/bench_quickopen.cpp
@@ -20,6 +20,9 @@
 
 #include "bench_quickopen.h"
 
+#include <interfaces/icore.h>
+#include <interfaces/iprojectcontroller.h>
+
 #include <QIcon>
 #include <QtTest/QTest>
 
diff --git a/plugins/quickopen/tests/quickopentestbase.cpp b/plugins/quickopen/tests/quickopentestbase.cpp
--- a/plugins/quickopen/tests/quickopentestbase.cpp
+++ b/plugins/quickopen/tests/quickopentestbase.cpp
@@ -57,7 +57,7 @@
 
 void QuickOpenTestBase::cleanup()
 {
-    projectController->clearProjects();
+    projectController->closeAllProjects();
     core->documentController()->closeAllDocuments();
 }
 
diff --git a/shell/project.h b/shell/project.h
--- a/shell/project.h
+++ b/shell/project.h
@@ -97,8 +97,7 @@
      */
     bool open(const Path &projectFile);
 
-    /** This method is invoked when the project needs to be closed. */
-    void close();
+    void close() override;
 
     IProjectFileManager* projectFileManager() const override;
     IBuildSystemManager* buildSystemManager() const override;
diff --git a/shell/projectcontroller.h b/shell/projectcontroller.h
--- a/shell/projectcontroller.h
+++ b/shell/projectcontroller.h
@@ -86,8 +86,6 @@
     virtual QItemSelectionModel* projectSelectionModel();
     IProject* findProjectByName( const QString& name ) override;
     IProject* findProjectForUrl( const QUrl& ) const override;
-    void addProject(IProject*);
-//     IProject* currentProject() const;
 
     bool isProjectNameUsed( const QString& name ) const override;
     void setDialogProvider(IProjectDialogProvider*);
@@ -105,6 +103,7 @@
     virtual void abortOpeningProject( IProject* );
     void projectImportingFinished( IProject* );
     void closeProject( IProject* ) override;
+    void closeAllProjects() override;
     void configureProject( IProject* ) override;
 
     void reparseProject( IProject* project, bool forceUpdate = false  ) override;
@@ -122,6 +121,22 @@
     Q_SCRIPTABLE QString mapSourceBuild( const QString& path, bool reverse = false, bool fallbackRoot = true ) const;
 
 protected:
+    /**
+     * Add the existing project @p project to the controller
+     *
+     * @note Method is used for testing objectives, consider using openProject() instead!
+     * @note takes ownership over the project
+     *
+     * @sa openProject()
+     */
+    void addProject(IProject* proj);
+    /**
+     * Remove the project @p project from the controller
+     *
+     * @note Ownership is passed on to the caller
+     */
+    void takeProject(IProject* proj);
+
     virtual void loadSettings( bool projectIsLoaded );
     virtual void saveSettings( bool projectIsLoaded );
 
diff --git a/shell/projectcontroller.cpp b/shell/projectcontroller.cpp
--- a/shell/projectcontroller.cpp
+++ b/shell/projectcontroller.cpp
@@ -70,6 +70,7 @@
 #include <vcs/widgets/vcscommitdialog.h>
 
 #include "core.h"
+// TODO: Should get rid off this include (should depend on IProject only)
 #include "project.h"
 #include "mainwindow.h"
 #include "shellextension.h"
@@ -578,9 +579,7 @@
         buildSetModel()->storeToSession( Core::self()->activeSession() );
     }
 
-    foreach( IProject* project, d->m_projects ) {
-        closeProject( project );
-    }
+    closeAllProjects();
 }
 
 void ProjectController::initialize()
@@ -887,31 +886,22 @@
     connect(proj, &IProject::destroyed, this, [&] { d->unloadAllProjectPlugins(); });
 }
 
-void ProjectController::closeProject(IProject* proj_)
+void ProjectController::takeProject(IProject* proj)
 {
-    if (!proj_)
-    {
+    if (!proj) {
         return;
     }
 
     // loading might have failed
-    d->m_currentlyOpening.removeAll(proj_->projectFile().toUrl());
-
-    Project* proj = dynamic_cast<KDevelop::Project*>( proj_ );
-    if( !proj )
-    {
-        qWarning() << "Unknown Project subclass found!";
-        return;
-    }
+    d->m_currentlyOpening.removeAll(proj->projectFile().toUrl());
     d->m_projects.removeAll(proj);
     emit projectClosing(proj);
     //Core::self()->saveSettings();     // The project file is being closed.
                                         // Now we can save settings for all of the Core
                                         // objects including this one!!
     unloadUnusedProjectPlugins(proj);
     closeAllOpenedFiles(proj);
     proj->close();
-    proj->deleteLater();                //be safe when deleting
     if (d->m_projects.isEmpty())
     {
         initializePluginCleanup(proj);
@@ -921,7 +911,19 @@
         d->saveListOfOpenedProjects();
 
     emit projectClosed(proj);
-    return;
+}
+
+void ProjectController::closeProject(IProject* proj)
+{
+    takeProject(proj);
+    proj->deleteLater(); // be safe when deleting
+}
+
+void ProjectController::closeAllProjects()
+{
+    foreach (auto project, d->m_projects) {
+        closeProject(project);
+    }
 }
 
 void ProjectController::abortOpeningProject(IProject* proj)
@@ -968,7 +970,17 @@
 
 void ProjectController::addProject(IProject* project)
 {
-    d->m_projects.append( project );
+    Q_ASSERT(project);
+    if (d->m_projects.contains(project)) {
+        qWarning() << "Project already tracked by this project controller:" << project;
+        return;
+    }
+
+    // fake-emit signals so listeners are aware of a new project being added
+    emit projectAboutToBeOpened(project);
+    project->setParent(this);
+    d->m_projects.append(project);
+    emit projectOpened(project);
 }
 
 QItemSelectionModel* ProjectController::projectSelectionModel()
diff --git a/tests/testproject.h b/tests/testproject.h
--- a/tests/testproject.h
+++ b/tests/testproject.h
@@ -60,6 +60,7 @@
     QList< ProjectFileItem* > filesForPath(const IndexedString&) const override;
     QList< ProjectFolderItem* > foldersForPath(const IndexedString&) const override { return QList<ProjectFolderItem*>(); }
     void reloadModel() override { }
+    void close() override {}
     Path projectFile() const override;
     KSharedConfigPtr projectConfiguration() const override { return m_projectConfiguration; }
     void addToFileSet( ProjectFileItem* file) override;
@@ -86,18 +87,19 @@
 class KDEVPLATFORMTESTS_EXPORT TestProjectController : public ProjectController
 {
     Q_OBJECT
+
 public:
     TestProjectController(Core* core) : ProjectController(core) {}
     IProject* projectAt( int i ) const override { return m_projects.at(i); }
     int projectCount() const override { return m_projects.count(); }
     QList<IProject*> projects() const override { return m_projects; }
+
 public:
-    void addProject(IProject* p);
-    void takeProject(IProject* p);
-    void clearProjects();
-    void closeProject(IProject* p) override;
+    using ProjectController::addProject;
+    using ProjectController::takeProject;
 
     void initialize() override;
+
 private:
     QList<IProject*> m_projects;
 };
diff --git a/tests/testproject.cpp b/tests/testproject.cpp
--- a/tests/testproject.cpp
+++ b/tests/testproject.cpp
@@ -126,36 +126,6 @@
     }
 }
 
-void TestProjectController::addProject(IProject* p)
-{
-    emit projectAboutToBeOpened(p);
-    p->setParent(this);
-    m_projects << p;
-    emit projectOpened(p);
-}
-
-void TestProjectController::clearProjects()
-{
-    foreach(IProject* p, m_projects) {
-        closeProject(p);
-    }
-}
-
-void TestProjectController::closeProject(IProject* p)
-{
-    emit projectClosing(p);
-    delete p;
-    m_projects.removeOne(p);
-    emit projectClosed(p);
-}
-
-void KDevelop::TestProjectController::takeProject(KDevelop::IProject* p)
-{
-    emit projectClosing(p);
-    m_projects.removeOne(p);
-    emit projectClosed(p);
-}
-
 void TestProjectController::initialize()
 {
 }