Be more robust in how regression data are discovered (#821)

* Ensure a test opens an expected array as read-only

Avoid creating an empty array when test_open does not find the expected
existing array.

* Ensure that the test fixture can be found

Regardless of the test runner working directory, ensure that this test
fixture returns the path to the relevant regression data directory,
which lives under the project root.

* Pass path strings, not pathlib.Paths, to FSStore

* Add release note

Author: benjaminhwilliams

docs/release.rst

@@ -6,6 +6,15 @@ Release notes
 Unreleased
 ----------
 
+.. _release_2.9.2:
+
+Maintenance
+~~~~~~~~~~~
+
+* Correct conda-forge deployment of Zarr by fixing some Zarr tests.
+  By :user:`Ben Williams <benjaminhwilliams>`; :issue:`821`.
+
+
 .. _release_2.9.1:
 
 Maintenance

zarr/tests/test_dim_separator.py

@@ -1,3 +1,5 @@
+import pathlib
+
 import pytest
 from numpy.testing import assert_array_equal
 
@@ -29,10 +31,11 @@ def dataset(tmpdir, request):
     kwargs = {}
 
     if which.startswith("static"):
+        project_root = pathlib.Path(zarr.__file__).resolve().parent.parent
         if which.endswith("nested"):
-            return "fixture/nested"
+            return str(project_root / "fixture/nested")
         else:
-            return "fixture/flat"
+            return str(project_root / "fixture/flat")
 
     if which.startswith("directory"):
         store_class = DirectoryStore
@@ -60,7 +63,7 @@ def verify(array):
 
 
 def test_open(dataset):
-    verify(zarr.open(dataset))
+    verify(zarr.open(dataset, "r"))
 
 
 @pytest.mark.skipif(have_fsspec is False, reason="needs fsspec")