Cover rounded ANCOVA summary stats in integration test.

Execute the `round_to` path in `PrePostNEGD._group_level_summary_stats()` so Codecov patch coverage includes the new group-level summary logic.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: drbenvincent

causalpy/tests/test_integration_pymc_examples.py

@@ -656,6 +656,16 @@ def test_ancova(mock_pymc_sample, capsys):
     assert "n" in output
     assert "pre_mean" in output
     assert "post_mean" in output
+    rounded_stats = result._group_level_summary_stats(round_to=1)
+    assert isinstance(rounded_stats, pd.DataFrame)
+    assert np.allclose(
+        rounded_stats["pre_mean"],
+        rounded_stats["pre_mean"].round(1),
+    )
+    assert np.allclose(
+        rounded_stats["post_mean"],
+        rounded_stats["post_mean"].round(1),
+    )
     fig, ax = result.plot()
     assert isinstance(fig, plt.Figure)
     # For multi-panel plots, ax should be an array of axes