Pytest ignores ROOT tests if ROOT is not installed.

lena/flow/iterators.py

@@ -3,7 +3,7 @@
 """
 try:
     from future_builtins import zip
-except ModuleNotFoundError:
+except ImportError:
     # not existent in Python 3.9
     pass
 import collections

lena/flow/read_root_file.py

@@ -3,8 +3,6 @@
 import inspect
 import sys
 
-import ROOT
-
 import lena
 
 
@@ -29,6 +27,11 @@ def __init__(self, types=None, keys=None, selector=None):
         If *selector* is given, both *types* and *keys* must
         be omitted, or :exc:`.LenaValueError` is raised.
         """
+        try:
+            import ROOT
+        except ImportError:
+            raise ImportError("ROOT not installed")
+
         if selector is not None:
             if keys or types:
                 raise lena.core.LenaValueError(
@@ -104,6 +107,7 @@ def run(self, flow):
         don't save yielded values to a list,
         or make proper copies of them in advance.
         """
+        import ROOT
         for val in flow:
             data, context = lena.flow.get_data_context(val)
 

lena/flow/read_root_tree.py

@@ -32,9 +32,6 @@ def __init__(self, branches=None, get_entry=None):
             e.g. *copy.deepcopy* in *get_entry*.
             Otherwise all items collected will be the last read value.
         """
-        # todo: should this class belong
-        # to lena.flow or lena.input, lena.readers?
-
         # This loads other classes faster,
         # and if ROOT is not installed,
         # still enables "from lena.flow import ReadROOTTree",

lena/output/write_root_tree.py

@@ -1,6 +1,4 @@
 # needs ROOT installed
-from __future__ import print_function
-
 import array
 import collections
 import copy

pytest.ini

@@ -3,6 +3,6 @@ filterwarnings =
     ignore:::markupsafe
 
 ## Ignore warnings from other packages ##
-
+#
 ## raised when using collections module (for named tuples).
 # /usr/lib64/python3.7/site-packages/markupsafe/__init__.py:13: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working

tests/conftest.py

@@ -0,0 +1,7 @@
+try:
+    import ROOT
+except ImportError:
+    collect_ignore_glob = ["*/root/*"]
+    # otherwise will have problems either with tox,
+    # or when executing pytest directly
+    collect_ignore_glob += ["root/*"]

tests/root/conftest.py

@@ -1,10 +1,31 @@
 import pytest
 
-from .test_write_root_tree import test_run
+# can't import it here, because
+# conftest will be always run irrespective of ROOT availability
+# from .test_write_root_tree import test_run
 
+# to mark all files from this directory as 'ROOT', see this answer:
+# https://stackoverflow.com/a/57046943/952234
+# copy here:
+"""
+import pathlib
+import pytest
+
+
+def pytest_collection_modifyitems(config, items):
+    # python 3.4/3.5 compat: rootdir = pathlib.Path(str(config.rootdir))
+    rootdir = pathlib.Path(config.rootdir)
+    for item in items:
+        rel_path = pathlib.Path(item.fspath).relative_to(rootdir)
+        mark_name = next((part for part in rel_path.parts if part.endswith('_tests')), '').rstrip('_tests')
+        if mark_name:
+            mark = getattr(pytest.mark, mark_name)
+            item.add_marker(mark)
+"""
 
 @pytest.fixture(scope="session")
 def rootfile():
+    from .test_write_root_tree import test_run
     # other ROOT tests depend on the existence of this file
     # test_run will be run twice: once here, and also when tested.
     filename = test_run()

tox.ini

@@ -16,3 +16,6 @@ deps =
     pytest-mock
 commands =
     pytest --doctest-modules lena tests
+# for tox to find installed ROOT bindings
+passenv = PYTHONPATH
+sitepackages = true