Fail on all warnings (#34)

pyproject.toml

@@ -60,6 +60,10 @@ addopts = "--strict-markers --strict-config -v -r sxfE --color=yes"
 xfail_strict = true
 python_files = ["test_*.py"]
 testpaths = ["xarray_extras/tests"]
+filterwarnings = [
+    "error",
+    "ignore:datetime.datetime.utcfromtimestamp():DeprecationWarning",
+]
 
 [tool.coverage.report]
 show_missing = true

xarray_extras/tests/test_stack.py

@@ -5,6 +5,12 @@
 
 from xarray_extras.stack import proper_unstack
 
+# FIXME https://github.com/crusaderky/xarray_extras/issues/33
+pytestmark = pytest.mark.filterwarnings(
+    "ignore:Updating MultiIndexed coordinate .* would corrupt indices",
+    "ignore:invalid value encountered in cast:RuntimeWarning",
+)
+
 
 def test_proper_unstack_order():
     # Note: using MultiIndex.from_tuples is NOT the same thing as