Clang: Make file ids unique

Clang file ids are only unique for one query. Because we query in parallel
we have to manage our own unique ids.

Change-Id: I67d57d8b1766cab75ad252a14e57bbf9dc5fdb79
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

tests/unit/unittest/filepath-test.cpp

@@ -0,0 +1,56 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** 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.
+**
+****************************************************************************/
+
+#include "googletest.h"
+
+#include <filepath.h>
+
+namespace {
+
+TEST(FilePath, CreateFromPathString)
+{
+    ClangBackEnd::FilePath filePath{Utils::PathString{"/file/pathOne"}};
+
+    ASSERT_THAT(filePath.directory(), "/file");
+    ASSERT_THAT(filePath.name(), "pathOne");
+}
+
+TEST(FilePath, CreateFromQString)
+{
+    ClangBackEnd::FilePath filePath{QString{"/file/pathOne"}};
+
+    ASSERT_THAT(filePath.directory(), "/file");
+    ASSERT_THAT(filePath.name(), "pathOne");
+}
+
+TEST(FilePath, EmptyFilePath)
+{
+    ClangBackEnd::FilePath filePath;
+
+    ASSERT_THAT(filePath.directory(), "");
+    ASSERT_THAT(filePath.name(), "");
+}
+
+}