Add Python wrapper to ecl and use it to test functionality

* Add SWIG interface definition (and external numpy interface) to ecl classes
* Add section in CMakeLists.txt to build Python bindings and execute
  Python-based tests
* Write (property-based) tests that show the basic functionality of the Python
  bindings and the EKF (using pytest and hypothesis libraries)
* Write minimal benchmark for the EKF update (using benchmark plugin for pytest)
* Add plotting utilities to analyze tests
* Add lint script to keep the Python scripts clean

EKF/tests/pytest/test_basics.py

@@ -0,0 +1,115 @@
+###############################################################################
+#
+# Copyright (c) 2017 Estimation and Control Library (ECL). 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 ECL 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,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+###############################################################################
+
+"""Basic tests and benchmarks testing the ecl's EKF
+
+@author: Peter Dürr <Peter.Duerr@sony.com>
+"""
+from __future__ import print_function
+from __future__ import unicode_literals
+from __future__ import division
+from __future__ import absolute_import
+
+import pytest
+
+from test_utils import ecl
+
+# Pylint does not like pytest fixtures, disable the warning
+# pylint: disable=redefined-outer-name
+from test_utils import update_sensors
+from test_utils import initialized_ekf  # pylint: disable=unused-import
+
+
+def test_filter_initialized(initialized_ekf):
+    """Make sure the EKF updates after a few IMU, Mag and Baro updates
+    """
+    ekf, _ = initialized_ekf
+    assert ekf.update()
+
+
+@pytest.mark.benchmark
+def test_ekf_imu_update_benchmark(initialized_ekf, benchmark):
+    """Benchmark the time for an ekf update using just IMU, mag and baro data
+    """
+    ekf, _ = initialized_ekf
+    benchmark(ekf.update)
+
+
+def test_status_on_imu_mag_baro(initialized_ekf):
+    """Make sure the EKF with zero inputs has reasonable status
+    """
+    ekf, _ = initialized_ekf
+    control_mode = ekf.get_control_mode()
+
+    assert control_mode.yaw_align
+    assert control_mode.gps is False
+    assert control_mode.opt_flow is False
+    assert control_mode.mag_hdg
+    assert control_mode.mag_3D is False
+    assert control_mode.mag_dec is False
+    assert control_mode.in_air is False
+    assert control_mode.wind is False
+    assert control_mode.baro_hgt
+    assert control_mode.rng_hgt is False
+    assert control_mode.gps_hgt is False
+    assert control_mode.ev_pos is False
+    assert control_mode.ev_yaw is False
+    assert control_mode.ev_hgt is False
+    assert control_mode.fuse_beta is False
+    assert control_mode.update_mag_states_only is False
+    assert control_mode.fixed_wing is False
+
+
+def test_converges_to_zero():
+    """Make sure the EKF with zero inputs converges to / stays at zero
+    """
+    ekf = ecl.Ekf()
+
+    time_usec = 1000
+    dt_usec = 5000
+
+    # Provide a few samples
+    for _ in range(10000):
+        update_sensors(ekf, time_usec, dt_usec)
+        ekf.update()
+        time_usec += dt_usec
+
+    converged_pos = ekf.get_position()
+    converged_vel = ekf.get_velocity()
+    converged_accel_bias = ekf.get_accel_bias()
+    converged_gyro_bias = ekf.get_gyro_bias()
+    for i in range(3):
+        assert converged_pos[i] == pytest.approx(0.0, abs=1e-6)
+        assert converged_vel[i] == pytest.approx(0.0, abs=1e-6)
+        assert converged_accel_bias[i] == pytest.approx(0.0, abs=1e-5)
+        assert converged_gyro_bias[i] == pytest.approx(0.0, abs=1e-5)