Add test for connection parsing

test/models/connection_test.dart

@@ -0,0 +1,59 @@
+import 'dart:convert';
+
+import 'package:db_construction_site/models/connection.dart';
+import 'package:db_construction_site/models/connection_type.dart';
+import 'package:db_construction_site/models/region.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('test if json parsing works as expected', () {
+    const exampleConnectionJsonString = """
+    {
+    "id": "3",
+    "name": "RE 17",
+    "kbnr": "430",
+    "von": "Warburg",
+    "verlauf": [
+      "Hagen Hbf",
+      "Arnsberg (Westf)",
+      "Meschede",
+      "Warburg (Westf)",
+      "Hofgeismar",
+      "Kassel-Wilhelmshöhe"
+    ],
+    "nach": "Kassel",
+    "via": "",
+    "timestamp": "2018-11-16 05:15:43",
+    "verfall": "2018-12-02 23:15:00",
+    "verbindung": "regional",
+    "fern_id": null,
+    "land": "hessen",
+    "url": "https://bauinfos.deutschebahn.com/hessen/Strecke/430-Warburg-Kassel/3",
+    "ics": "https://bauinfos.deutschebahn.com/docs/hessen/ical-hessen-430.ics",
+    "doc": "https://bauinfos.deutschebahn.com/docs/hessen/430.pdf",
+    "meldungen": [],
+    "infos": []
+  }
+    """;
+    Map<String, dynamic> json;
+    try {
+      json = JsonDecoder().convert(exampleConnectionJsonString);
+      assert(json != null);
+    } catch (e) {
+      print("JSON decoding failed, skipping test.");
+      return;
+    }
+    final connection = Connection.fromJson(json);
+    expect(connection.id, "3");
+    expect(connection.name, "RE 17");
+    expect(connection.courseBookNumber, "430");
+    expect(connection.origin, "Warburg");
+    expect(connection.stops, contains("Hagen Hbf"));
+    expect(connection.destination, "Kassel");
+    expect(connection.via, "");
+    expect(connection.timestamp, DateTime(2018, 11, 16, 05, 15, 43));
+    expect(connection.expiryDate, DateTime(2018, 12, 02, 23, 15, 00));
+    expect(connection.type, ConnectionType.regional);
+    expect(connection.region, Region.hesse);
+  });
+}