Add unit-tests

tests/test_cli.py

@@ -0,0 +1,23 @@
+import sys
+from io import StringIO
+from unittest import mock
+from redmine_reporter.cli import main
+
+
+@mock.patch.dict("os.environ", {
+    "REDMINE_URL": "https://red.eltex.loc/",
+    "REDMINE_USER": "x",
+    "REDMINE_PASSWORD": "y"
+})
+@mock.patch("redmine_reporter.client.fetch_issues_with_spent_time")
+def test_cli_smoke(mock_fetch):
+    mock_fetch.return_value = []
+    old_stdout = sys.stdout
+    sys.stdout = captured = StringIO()
+    try:
+        code = main(["--date", "2026-01-01--2026-01-31"])
+        assert code == 0
+        output = captured.getvalue()
+        assert "Total issues: 0" in output
+    finally:
+        sys.stdout = old_stdout