introduce first test for streamlit app

requirements.txt

@@ -1,6 +1,6 @@
 pandas~=2.1
 numpy~=1.25
-streamlit~=1.26
+streamlit>=1.28
 openpyxl~=3.1
 plotly~=5.16
 faker~=18.9

tests/test_ptxboa_streamlit.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+"""Tests for the streamlit app."""
+import pytest
+from streamlit.testing.v1 import AppTest
+
+
+@pytest.fixture
+def running_app():
+    """Fixture that returns a fresh instance of a running app."""
+    at = AppTest.from_file("ptxboa_streamlit.py")
+    at.run(timeout=20)
+    return at
+
+
+def test_app_smoke(running_app):
+    """Test if the app starts up without errors."""
+    assert not running_app.exception