tests: finally another test!

tests.py

@@ -1,4 +1,54 @@
+from typing import TypedDict
+import pytest
+import logging
+
+from teilchensammler_cli.models import TeilchenCreate, make_teilchen_input
+
+logger = logging.getLogger(__name__)
+
+
 def test_initial_layout(snap_compare):
     from teilchensammler_cli.main import app
 
     assert snap_compare(app, terminal_size=(130, 40))
+
+
+class Teilchen(TypedDict):
+    """The things I do for my LSP..."""
+
+    name: str
+    description: str
+    tags: str
+    text: str
+    number: int
+
+
+empty_teilchen: Teilchen = {
+    "name": "",
+    "description": "",
+    "tags": "",
+    "text": "",
+    "number": 1,
+}
+
+
+@pytest.mark.parametrize(
+    "example_input,expected",
+    [
+        ("", None),
+        ("a", None),
+        ("a.", {"name": "a", "text": "a."}),
+        ("aa", None),
+        ("aa.", {"name": "aa", "text": "aa."}),
+    ],
+)
+async def test_teilchendata_must_include_period(
+    example_input: str, expected: dict[str, str | int] | None
+) -> None:
+
+    thing = expected
+    if expected:
+        arguments = empty_teilchen | expected
+        thing = TeilchenCreate(**arguments)  # ty:ignore[invalid-argument-type]
+
+    assert await make_teilchen_input(example_input) == thing