Improve lifetime validation exception

The message now includes the problematic values.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/client/microgrid/_lifetime.py

@@ -33,7 +33,9 @@ class Lifetime:
     def __post_init__(self) -> None:
         """Validate this lifetime."""
         if self.start is not None and self.end is not None and self.start > self.end:
-            raise ValueError("Start must be before or equal to end.")
+            raise ValueError(
+                f"Start ({self.start}) must be before or equal to end ({self.end})"
+            )
 
     def is_operational_at(self, timestamp: datetime) -> bool:
         """Check whether this lifetime is active at a specific timestamp."""

tests/test_lifetime.py

@@ -200,7 +200,9 @@ def test_validation(
     )
 
     if should_fail:
-        with pytest.raises(ValueError, match="Start must be before or equal to end."):
+        with pytest.raises(
+            ValueError, match=r"Start \(.*\) must be before or equal to end \(.*\)"
+        ):
             Lifetime(start=start_time, end=end_time)
     else:
         lifetime = Lifetime(start=start_time, end=end_time)