test: media_device: Create a common MediaDeviceTest base class

Before adding more tests which will act on the vimc pipeline break out a
common base from media_device_link_test.cpp which already acts on vimc.
The new common base class will help reduce code duplication.

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

test/media_device/media_device_test.cpp

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * media_device_test.cpp - libcamera media device test base class
+ */
+
+#include <iostream>
+
+#include "media_device_test.h"
+
+using namespace libcamera;
+using namespace std;
+
+int MediaDeviceTest::init()
+{
+	enumerator_ = unique_ptr<DeviceEnumerator>(DeviceEnumerator::create());
+	if (!enumerator_) {
+		cerr << "Failed to create device enumerator" << endl;
+		return TestFail;
+	}
+
+	if (enumerator_->enumerate()) {
+		cerr << "Failed to enumerate media devices" << endl;
+		return TestFail;
+	}
+
+	DeviceMatch dm("vimc");
+	media_ = enumerator_->search(dm);
+	if (!media_) {
+		cerr << "No VIMC media device found: skip test" << endl;
+		return TestSkip;
+	}
+
+	return TestPass;
+}