TestKdbx4Format: use MockClock

Otherwise, assertions in TestKdbx4::testCustomData() may fail on rare
occasions, because the customData in a cloned entry won't be identical
to its original, because of its potentially-updated LastModified
property.

Originally noticed in
keepassxreboot#7783 (comment).

tests/TestKdbx4.cpp

@@ -27,6 +27,7 @@
 #include "keys/FileKey.h"
 #include "keys/PasswordKey.h"
 #include "mock/MockChallengeResponseKey.h"
+#include "mock/MockClock.h"
 #include <QTest>
 
 int main(int argc, char* argv[])
@@ -113,6 +114,17 @@ void TestKdbx4AesKdf::initTestCaseImpl()
 }
 
 Q_DECLARE_METATYPE(QUuid)
+
+void TestKdbx4Format::init()
+{
+    MockClock::setup(new MockClock());
+}
+
+void TestKdbx4Format::cleanup()
+{
+    MockClock::teardown();
+}
+
 void TestKdbx4Format::testFormat400()
 {
     QString filename = QString(KEEPASSX_TEST_DATA_DIR).append("/Format400.kdbx");

tests/TestKdbx4.h

@@ -56,6 +56,8 @@ class TestKdbx4Format : public QObject
     Q_OBJECT
 
 private slots:
+    void init();
+    void cleanup();
     void testFormat400();
     void testFormat400Upgrade();
     void testFormat400Upgrade_data();