replace test tags with pytest.mark

replaced the __tags__ class attribute and the
--exclude-tags / --include-tags test runner options
with regular pytest.mark names
so that we can take advantage of mark expressions.
options --nomemory, --notimingintensive, --backend-only,
--exclude-tags, --include-tags remain as legacy but
make use of pytest mark for implemementation.

Added a "mypy" mark for the section of tests that are doing mypy
integration tests.

The __backend__ and __sparse_backend__ class attributes also
use pytest marks for their implementation, which also allows
the marks "backend" and "sparse_backend" to be used explicitly.

Also removed the no longer used "--cdecimal" option as this was
python 2 specific.

in theory, the usage of pytest marks could expand such that
the whole exclusions system would be based on it, but this
does not seem to have any advantage at the moment.

Change-Id: Ideeb57d9d49f0efc7fc0b6b923b31207ab783025

1 files changed, 46 insertions, 6 deletions

diff --git a/lib/sqlalchemy/testing/plugin/pytestplugin.py b/lib/sqlalchemy/testing/plugin/pytestplugin.py
index 2ae6730bb..363a73ecc 100644
--- a/lib/sqlalchemy/testing/plugin/pytestplugin.py
+++ b/lib/sqlalchemy/testing/plugin/pytestplugin.py
@@ -69,6 +69,17 @@ def pytest_addoption(parser):
 
 
 def pytest_configure(config):
+    if plugin_base.exclude_tags or plugin_base.include_tags:
+        if config.option.markexpr:
+            raise ValueError(
+                "Can't combine explicit pytest marks with legacy options "
+                "such as --backend-only, --exclude-tags, etc. "
+            )
+        config.option.markexpr = " and ".join(
+            list(plugin_base.include_tags)
+            + [f"not {tag}" for tag in plugin_base.exclude_tags]
+        )
+
     if config.pluginmanager.hasplugin("xdist"):
         config.pluginmanager.register(XDistHooks())
 
@@ -206,18 +217,43 @@ def pytest_collection_modifyitems(session, config, items):
 
     def setup_test_classes():
         for test_class in test_classes:
+
+            # transfer legacy __backend__ and __sparse_backend__ symbols
+            # to be markers
+            add_markers = set()
+            if getattr(test_class.cls, "__backend__", False) or getattr(
+                test_class.cls, "__only_on__", False
+            ):
+                add_markers = {"backend"}
+            elif getattr(test_class.cls, "__sparse_backend__", False):
+                add_markers = {"sparse_backend"}
+            else:
+                add_markers = frozenset()
+
+            existing_markers = {
+                mark.name for mark in test_class.iter_markers()
+            }
+            add_markers = add_markers - existing_markers
+            all_markers = existing_markers.union(add_markers)
+
+            for marker in add_markers:
+                test_class.add_marker(marker)
+
             for sub_cls in plugin_base.generate_sub_tests(
-                test_class.cls, test_class.module
+                test_class.cls, test_class.module, all_markers
             ):
                 if sub_cls is not test_class.cls:
                     per_cls_dict = rebuilt_items[test_class.cls]
 
                     module = test_class.getparent(pytest.Module)
-                    for fn in collect(
-                        pytest.Class.from_parent(
-                            name=sub_cls.__name__, parent=module
-                        )
-                    ):
+
+                    new_cls = pytest.Class.from_parent(
+                        name=sub_cls.__name__, parent=module
+                    )
+                    for marker in add_markers:
+                        new_cls.add_marker(marker)
+
+                    for fn in collect(new_cls):
                         per_cls_dict[fn.name].append(fn)
 
     # class requirements will sometimes need to access the DB to check
@@ -573,6 +609,10 @@ class PytestFixtureFunctions(plugin_base.FixtureFunctions):
     def skip_test_exception(self, *arg, **kw):
         return pytest.skip.Exception(*arg, **kw)
 
+    @property
+    def add_to_marker(self):
+        return pytest.mark
+
     def mark_base_test_class(self):
         return pytest.mark.usefixtures(
             "setup_class_methods", "setup_test_methods"