Add interval tests

Author: dstansby

src/napari_matplotlib/tests/test_util.py

@@ -0,0 +1,15 @@
+import pytest
+
+from napari_matplotlib.util import Interval
+
+
+def test_interval():
+    interval = Interval(4, 9)
+    for i in range(4, 10):
+        assert i in interval
+
+    assert 3 not in interval
+    assert 10 not in interval
+
+    with pytest.raises(ValueError, match="must be an integer"):
+        "string" in interval

src/napari_matplotlib/util.py

@@ -21,7 +21,7 @@ def __init__(self, lower_bound: Optional[int], upper_bound: Optional[int]):
 
     def __contains__(self, val):
         if not isinstance(val, int):
-            return NotImplemented
+            raise ValueError("variable must be an integer")
         if self.lower is not None and val < self.lower:
             return False
         if self.upper is not None and val > self.upper: