tests

src/textual/_duration.py

@@ -18,11 +18,11 @@ class DurationParseError(DurationError):
 def _duration_as_seconds(duration: str) -> float:
     """
     Args:
-        duration: A string of the form ``"2s"`` or ``"300ms"``, representing 2 seconds and
-            300 milliseconds respectively. If no unit is supplied, e.g. ``"2"``, then the duration is
+        duration: A string of the form `"2s"` or `"300ms"`, representing 2 seconds and
+            300 milliseconds respectively. If no unit is supplied, e.g. `"2"`, then the duration is
             assumed to be in seconds.
     Raises:
-        DurationParseError: If the argument ``duration`` is not a valid duration string.
+        DurationParseError: If the argument `duration` is not a valid duration string.
     Returns:
         The duration in seconds.
     """
@@ -39,8 +39,6 @@ def _duration_as_seconds(duration: str) -> float:
         try:
             duration_secs = float(duration)
         except ValueError:
-            raise DurationParseError(
-                f"{duration!r} is not a valid duration."
-            ) from ValueError
+            raise DurationParseError(f"{duration!r} is not a valid duration.") from None
 
     return duration_secs

tests/test_duration.py

@@ -0,0 +1,15 @@
+import pytest
+
+from textual._duration import DurationParseError, _duration_as_seconds
+
+
+def test_parse() -> None:
+    assert _duration_as_seconds("30") == 30.0
+    assert _duration_as_seconds("30s") == 30.0
+    assert _duration_as_seconds("30000ms") == 30.0
+    assert _duration_as_seconds("0.5") == 0.5
+    assert _duration_as_seconds("0.5s") == 0.5
+    assert _duration_as_seconds("500ms") == 0.5
+
+    with pytest.raises(DurationParseError):
+        _duration_as_seconds("300x")

tests/test_node_list.py

@@ -16,6 +16,16 @@ def test_add_one():
     assert len(nodes) == 1
 
 
+def test_length_hint():
+    """Check length hint dunder method."""
+    nodes = NodeList()
+    assert nodes.__length_hint__() == 0
+    nodes._append(Widget())
+    nodes._append(Widget())
+    nodes._append(Widget())
+    assert nodes.__length_hint__() == 3
+
+
 def test_repeat_add_one():
     """Does adding the same item to the node list ignore the additional adds?"""
     nodes = NodeList()