Edge case: threshold outside of [0.0, 1.0]

Author: jakechirsch

pandas/core/tools/datetimes.py

@@ -1029,6 +1029,9 @@ def to_datetime(
     if arg is None:
         return NaT
 
+    if not (0.0 <= threshold <= 1.0):
+        raise ValueError(f"`threshold` must be between 0.0 and 1.0, got {threshold}")
+
     if origin != "unix":
         arg = _adjust_to_origin(arg, origin, unit)
 

pandas/tests/tools/test_to_datetime.py

@@ -4155,3 +4155,22 @@ def test_example(self):
             threshold=0.5,
         )
         assert isna(result)
+
+    def test_bad_threshold(self):
+        with pytest.raises(
+            ValueError, match="`threshold` must be between 0.0 and 1.0, got -0.5"
+        ):
+            _ = to_datetime(
+                "2020-01-01 12:20:20",
+                format="%Y-%m-%d %H:%M:%S",
+                threshold=-0.5,
+            )
+
+        with pytest.raises(
+            ValueError, match="`threshold` must be between 0.0 and 1.0, got 2.0"
+        ):
+            _ = to_datetime(
+                "2020-01-01 12:20:20",
+                format="%Y-%m-%d %H:%M:%S",
+                threshold=2.0,
+            )