Robustify timestamp checks (#729)

* Robustify timestamp checks

* Remove lowerbound on sensor timestamp

* Add tests for fusion timeouts

* Inline and const time check functions

* Rename dead_reckoning time variable

test/test_EKF_gps.cpp

@@ -0,0 +1,85 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2019 ECL Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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+ *
+ ****************************************************************************/
+
+/**
+ * Test the gps fusion
+ * @author Kamil Ritz <ka.ritz@hotmail.com>
+ */
+
+#include <gtest/gtest.h>
+#include "EKF/ekf.h"
+#include "sensor_simulator/sensor_simulator.h"
+#include "sensor_simulator/ekf_wrapper.h"
+
+
+class EkfGpsTest : public ::testing::Test {
+ public:
+
+	EkfGpsTest(): ::testing::Test(),
+	_ekf{std::make_shared<Ekf>()},
+	_sensor_simulator(_ekf),
+	_ekf_wrapper(_ekf) {};
+
+	std::shared_ptr<Ekf> _ekf;
+	SensorSimulator _sensor_simulator;
+	EkfWrapper _ekf_wrapper;
+
+	// Setup the Ekf with synthetic measurements
+	void SetUp() override
+	{
+		_ekf->init(0);
+		_sensor_simulator.runSeconds(2);
+		_ekf_wrapper.enableGpsFusion();
+		_sensor_simulator.startGps();
+		_sensor_simulator.runSeconds(11);
+	}
+
+	// Use this method to clean up any memory, network etc. after each test
+	void TearDown() override
+	{
+	}
+};
+
+TEST_F(EkfGpsTest, gpsTimeout)
+{
+	// GIVEN:EKF that fuses GPS
+
+	// WHEN: setting the PDOP to high
+	_sensor_simulator._gps.setNumberOfSatellites(3);
+
+	// THEN: EKF should stop fusing GPS
+	_sensor_simulator.runSeconds(20);
+
+	// TODO: this is not happening as expected
+	EXPECT_TRUE(_ekf_wrapper.isIntendingGpsFusion());
+}