Add tests on adjusting rails geometry; configure GitHub Actions for the tests

.github/workflows/python-app.yml

@@ -0,0 +1,39 @@
+# This workflow will install Python dependencies, run tests and lint with a single version of Python
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
+
+name: Python application
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Python 3.6
+      uses: actions/setup-python@v3
+      with:
+        python-version: "3.6"
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install flake8
+        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+    - name: Lint with flake8
+      run: |
+        # stop the build if there are Python syntax errors or undefined names
+        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
+        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+    - name: Test with unittest
+      run: |
+        python -m unittest discover tests

subway_structure.py

@@ -1093,7 +1093,7 @@ class Route:
         first_stop_location = find_segment(self.stops[0].stop, tracks, 0)
         last_stop_location = find_segment(self.stops[-1].stop, tracks, 0)
 
-        if last_stop_location:
+        if last_stop_location != (None, None):
             seg2, u2 = last_stop_location
             if u2 == 0.0:
                 # Make seg2 the segment the last_stop_location is
@@ -1104,7 +1104,7 @@ class Route:
                 tracks = tracks[0:seg2 + 2]
             tracks[-1] = self.stops[-1].stop
 
-        if first_stop_location:
+        if first_stop_location != (None, None):
             seg1, u1 = first_stop_location
             if u1 == 1.0:
                 # Make seg1 the segment the first_stop_location is

tests/test_build_tracks.py

@@ -0,0 +1,107 @@
+"""
+To perform tests manually, run this command from the top directory
+of the repository:
+
+> python -m unittest discover tests
+
+or simply
+
+> python -m unittest
+"""
+
+import io
+import unittest
+
+from subway_structure import City
+from subway_io import load_xml
+from tests.sample_data import sample_networks
+
+
+class TestOneRouteTracks(unittest.TestCase):
+    """Test tracks extending and truncating on one-route networks"""
+
+    STATION_COUNT_INDEX = 4
+    CITY_TEMPLATE = [
+        1,  # city id
+        "Null Island",  # name
+        "World",  # Country
+        "Africa",  # continent
+        None,  # station count. Would be taken from the sample network data under testing
+        1,  # subway line count
+        0,  # light rail line count
+        0,  # interchanges
+        "-179, -89, 179, 89",  # bbox
+    ]
+
+    def prepare_city_routes(self, network):
+        city_data = self.CITY_TEMPLATE.copy()
+        city_data[self.STATION_COUNT_INDEX] = network["station_count"]
+        city = City(city_data)
+        elements = load_xml(io.BytesIO(network["xml"].encode("utf-8")))
+        for el in elements:
+            city.add(el)
+        city.extract_routes()
+        city.validate()
+
+        self.assertTrue(city.is_good())
+
+        route_master = list(city.routes.values())[0]
+        variants = route_master.routes
+
+        fwd_route = [v for v in variants if v.name == "Forward"][0]
+        bwd_route = [v for v in variants if v.name == "Backward"][0]
+
+        return fwd_route, bwd_route
+
+    def _test_tracks_extending_for_network(self, network_data):
+        fwd_route, bwd_route = self.prepare_city_routes(network_data)
+
+        self.assertEqual(
+            fwd_route.tracks,
+            network_data["tracks"],
+            "Wrong tracks",
+        )
+        extended_tracks = fwd_route.get_extended_tracks()
+        self.assertEqual(
+            extended_tracks,
+            network_data["extended_tracks"],
+            "Wrong tracks after extending",
+        )
+
+        self.assertEqual(
+            bwd_route.tracks,
+            network_data["tracks"][::-1],
+            "Wrong backward tracks",
+        )
+        extended_tracks = bwd_route.get_extended_tracks()
+        self.assertEqual(
+            extended_tracks,
+            network_data["extended_tracks"][::-1],
+            "Wrong backward tracks after extending",
+        )
+
+    def _test_tracks_truncating_for_network(self, network_data):
+        fwd_route, bwd_route = self.prepare_city_routes(network_data)
+
+        truncated_tracks = fwd_route.get_truncated_tracks(fwd_route.tracks)
+        self.assertEqual(
+            truncated_tracks,
+            network_data["truncated_tracks"],
+            "Wrong tracks after truncating",
+        )
+        truncated_tracks = bwd_route.get_truncated_tracks(bwd_route.tracks)
+        self.assertEqual(
+            truncated_tracks,
+            network_data["truncated_tracks"][::-1],
+            "Wrong backward tracks after truncating",
+        )
+
+    def test_tracks_extending(self):
+        for network_name, network_data in sample_networks.items():
+            with self.subTest(msg=network_name):
+                self._test_tracks_extending_for_network(network_data)
+
+    def test_tracks_truncating(self):
+        for network_name, network_data in sample_networks.items():
+            with self.subTest(msg=network_name):
+                self._test_tracks_truncating_for_network(network_data)