Rework slam streamer for easier testing

tracking/devices/factory.py

@@ -0,0 +1,10 @@
+from tracking.devices.mock_lidar import MockLidar
+from rplidar import RPLidar
+import tracking.lidar_loader as loader
+
+
+def get_lidar(connection: str):
+    if connection == 'TEST':
+        return MockLidar(loader.load_scans_bytes_file("tracking/out.pickle"))
+    else:
+        return RPLidar(connection)

tracking/devices/mock_lidar.py

@@ -0,0 +1,43 @@
+"""
+This module contains a MockLidar class, for use in place of RPLidar.
+Importantly, it implements iter_scans, so it can be substituted for RPLidar
+in the lidar_cache for testing (or anywhere else the rplidar may be used)
+"""
+
+import tracking.lidar_loader as loader
+
+
+class MockLidar:
+
+    def __init__(self, scan_iter=None):
+        """
+        Create mock lidar with an iterator that can be used as fake (or reused) scan data.
+
+        Examples
+        --------
+        lidar = MockLidar(scans)
+        first_scan = next(lidar.iter_scans(measurements=100))
+
+        Parameters
+        ----------
+
+        scan_iter: Iterable
+            An iterator that will generate/provide the fake/old scan data. 
+
+        """
+        self._iter = scan_iter
+
+    def iter_scans(self, min_len=100):
+        return iter(self._iter)
+
+    def get_health(self):
+        return "Mock Lidar has scans" if self._iter is not None else "Mock lidar won't work properly!"
+
+    def get_info(self):
+        return self.get_health()
+
+    def stop(self):
+        pass
+
+    def disconnect(self):
+        pass