Improve error message and test

adamchainz · Sep 19, 2023 · 6c5694a · 6c5694a
1 parent 44bc939
commit 6c5694a
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/src/time_machine/__init__.py b/src/time_machine/__init__.py
@@ -440,7 +440,7 @@ def move_to(
         def shift(self, delta: dt.timedelta | int | float) -> None:
             if self.traveller is None:
                 raise RuntimeError(
-                    "Initialize with `move_to()` first before using `shift()`"
+                    "Initialize time_machine with move_to() before using shift()."
                 )
             assert self.coordinates is not None
             self.coordinates.shift(delta=delta)

diff --git a/tests/test_time_machine.py b/tests/test_time_machine.py
@@ -733,9 +733,13 @@ def test_fixture_move_to_and_shift(time_machine):
 
 
 def test_fixture_shift_without_move_to(time_machine):
-    with pytest.raises(RuntimeError):
+    with pytest.raises(RuntimeError) as excinfo:
         time_machine.shift(100)
 
+    assert excinfo.value.args == (
+        "Initialize time_machine with move_to() before using shift().",
+    )
+
 
 # escape hatch tests