test: v4l2_device: Add test suite and initial test

Provide a base class to construct a v4l2_device object for further tests
and an initial test which validates the FD handle can not be leaked.

Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/v4l2_device/double_open.cpp

@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * libcamera V4L2 API tests
+ */
+
+#include <iostream>
+
+#include "v4l2_device_test.h"
+
+namespace {
+
+class DoubleOpen : public V4L2DeviceTest
+{
+protected:
+	int run()
+	{
+		int ret;
+
+		/*
+		 * Expect failure: The device has already been opened by the
+		 * V4L2DeviceTest base class
+		 */
+		ret = dev_->open();
+		if (!ret) {
+			std::cout << "Double open erroneously succeeded" << std::endl;
+			dev_->close();
+			return TestFail;
+		}
+
+		return TestPass;
+	}
+};
+
+} /* namespace */
+
+TEST_REGISTER(DoubleOpen);