Added test and comments about #137

Author: Sylvain MARIE

pytest_cases/plugin.py

@@ -890,7 +890,7 @@ def _cleanup_calls_list(metafunc, fix_closure_tree, calls, nodes, pending):
     if nb_calls != len(nodes):
         raise ValueError("This should not happen !")
 
-    # function_scope_num = get_pytest_function_scopenum()
+    function_scope_num = get_pytest_function_scopenum()
 
     for i in range(nb_calls):
         c, n = calls[i], nodes[i]
@@ -921,17 +921,16 @@ def _cleanup_calls_list(metafunc, fix_closure_tree, calls, nodes, pending):
         #
         # For this we use a dirty hack: we add a parameter with they name in the callspec, it seems to be propagated
         # in the `request`. TODO is there a better way?
-        f_scope = get_pytest_function_scopenum()
         for fixture_name in fix_closure_tree.get_not_always_used():
+            # (a) retrieve fixture scope
             try:
                 fixdef = metafunc._arg2fixturedefs[fixture_name]  # noqa
             except KeyError:
                 continue  # dont raise any error here and let pytest say "not found"
-
             this_scopenum = fixdef[-1].scopenum
 
-            # only do this for function-scoped fixtures, module or session scoped fixtures should remain active
-            if this_scopenum == f_scope:
+            # (b) only do this for function-scoped fixtures, module or session scoped fixtures should remain active
+            if this_scopenum == function_scope_num:
                 if fixture_name not in c.params and fixture_name not in c.funcargs:
                     if not n.requires(fixture_name):
                         # explicitly add it as discarded by creating a parameter value for it.
@@ -944,6 +943,18 @@ def _cleanup_calls_list(metafunc, fix_closure_tree, calls, nodes, pending):
                         c.indices[fixture_name] = 0
                         c._arg2scopenum[fixture_name] = this_scopenum  # get_pytest_scopenum(fixdef[-1].scope)  # noqa
 
+    # finally, if there are some session or module-scoped fixtures that
+    # are used in *none* of the calls, they could be deactivated too
+    # (see https://github.com/smarie/python-pytest-cases/issues/137)
+    #
+    # for fixture_name in fix_closure_tree.get_not_always_used():
+    #     # (a) retrieve fixture scope
+    #     ...
+    #     # (b) for non function-scoped fixtures
+    #     if this_scopenum != function_scope_num:
+    #         # to do check if there is at least one call that actually uses the fixture and is not skipped...
+    #         # this seems a bit "too much" !! > WONT FIX
+
 
 # def get_calls_for_partition(metafunc, super_closure, p_idx, pending):
 #     """

pytest_cases/tests/pytest_extension/fixtures/fixture_unions/test_fixture_union_setup_teardown2.py

@@ -2,6 +2,13 @@
 #          + All contributors to <https://github.com/smarie/python-pytest-cases>
 #
 # License: 3-clause BSD, <https://github.com/smarie/python-pytest-cases/blob/master/LICENSE>
+#
+# This is a more complex version of test_fixture_union_setup_teardown3.py
+# but the idea is the same: find a configuration in which the "smart reordering" of pytest
+# can not group test nodes together, so that we have session- and module-scoped fixtures
+# used and not used, alternatively. The objective is to check that they are not called several times
+# in spite of them being used/not used alternatively in test nodes.
+#
 from collections import defaultdict
 
 from pytest_cases import fixture, fixture_union, parametrize

pytest_cases/tests/pytest_extension/fixtures/fixture_unions/test_fixture_union_setup_teardown3.py

@@ -0,0 +1,36 @@
+# Authors: Sylvain MARIE <[email protected]>
+#          + All contributors to <https://github.com/smarie/python-pytest-cases>
+#
+# License: 3-clause BSD, <https://github.com/smarie/python-pytest-cases/blob/master/LICENSE>
+#
+# In this test we make sure that a session-scoped fixture is setup only once even if it is
+# not used in all test nodes because one parametrized test (TestFoo.test_b) requires a fixture union where
+# it is not always used.
+from pytest_cases import fixture, fixture_ref, parametrize
+
+fa_used = False
+
+
+@fixture(scope='session')
+def fa(request):
+    global fa_used
+    assert not fa_used
+    fa_used = True
+    return
+
+
+@fixture(scope='session')
+def fb():
+    return
+
+
+class TestFoo:
+    def test_a(self, fa):
+        pass
+
+    @parametrize("o", [fixture_ref(fa), fixture_ref(fb), fixture_ref(fa)])
+    def test_b(self, o):
+        pass
+
+    def test_c(self, fa):
+        pass