test: add full test suite with 100% coverage across all modules

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_routes.py

@@ -42,3 +42,23 @@ class TestScoreboardRoute:
         response = flask_client.get("/scoreboard")
         data = json.loads(response.data)
         assert "error" in data
+
+    def test_invalid_json_returns_error(self, flask_client, monkeypatch, tmp_path):
+        import app.routes as routes
+
+        bad_file = tmp_path / "bad.json"
+        bad_file.write_text("not valid json {{{")
+        monkeypatch.setattr(routes, "SCOREBOARD_DATA_FILE", str(bad_file))
+        response = flask_client.get("/scoreboard")
+        data = json.loads(response.data)
+        assert "error" in data
+
+    def test_null_json_returns_error(self, flask_client, monkeypatch, tmp_path):
+        import app.routes as routes
+
+        null_file = tmp_path / "null.json"
+        null_file.write_text("null")
+        monkeypatch.setattr(routes, "SCOREBOARD_DATA_FILE", str(null_file))
+        response = flask_client.get("/scoreboard")
+        data = json.loads(response.data)
+        assert "error" in data