Add ability to selectively not shuffle tests by using markers

README.rst

@@ -160,6 +160,15 @@ You can disable behaviours you don't like with the following flags:
   the start of every test
 * ``--randomly-dont-reorganize`` - turn off the shuffling of the order of tests
 
+Or you can selectively disable the shuffling of the test order with the
+``randomly_dont_reorganize`` marker:
+
+* ``pytestmark = pytest.mark.randomly_dont_reorganize`` - disable shuffling for
+  all tests in a module
+* ``@pytest.mark.randomly_dont_reorganize`` - disable shuffling for a class or function
+Note: if using the marker on individual tests, all functions inside a module must be marked,
+due to how the plugin shuffles test execution order
+
 The plugin appears to Pytest with the name 'randomly'. To disable it
 altogether, you can use the ``-p`` argument, for example:
 

pyproject.toml

@@ -12,6 +12,9 @@ addopts = """\
     --strict-config
     --strict-markers
     """
+markers = [
+    "randomly_dont_reorganize: Do not shuffle marked class or module",
+]
 
 [tool.mypy]
 mypy_path = "src/"

src/pytest_randomly/__init__.py

@@ -229,12 +229,14 @@ def pytest_collection_modifyitems(config: Config, items: list[Item]) -> None:
 
     modules_items: list[tuple[ModuleType | None, list[Item]]] = []
     for module, group in groupby(items, _get_module):
-        modules_items.append(
-            (
-                module,
-                _shuffle_by_class(list(group), seed),
-            )
-        )
+        module_items = list(group)
+
+        for item in module_items:
+            if not item.get_closest_marker("randomly_dont_reorganize"):
+                module_items = _shuffle_by_class(module_items, seed)
+                break
+
+        modules_items.append((module, module_items))
 
     def _module_key(module_item: tuple[ModuleType | None, list[Item]]) -> bytes:
         module, _items = module_item
@@ -262,7 +264,12 @@ def _item_key(item: Item) -> bytes:
 
     for klass, group in groupby(items, _get_cls):
         klass_items = list(group)
-        klass_items.sort(key=_item_key)
+
+        for item in klass_items:
+            if not item.get_closest_marker("randomly_dont_reorganize"):
+                klass_items.sort(key=_item_key)
+                break
+
         klasses_items.append((klass, klass_items))
 
     def _cls_key(klass_items: tuple[type[Any] | None, list[Item]]) -> bytes:

tests/test_pytest_randomly.py

@@ -350,6 +350,107 @@ def test_d(self):
     ]
 
 
+def test_class_test_methods_not_reordered_if_marked(ourtester):
+    ourtester.makepyfile(
+        test_one="""
+        import pytest
+
+        from unittest import TestCase
+
+        @pytest.mark.randomly_dont_reorganize
+        class T(TestCase):
+            def test_a(self):
+                pass
+
+            def test_b(self):
+                pass
+
+            def test_c(self):
+                pass
+
+            def test_d(self):
+                pass
+        """
+    )
+    args = ["-v", "--randomly-seed=15"]
+
+    out = ourtester.runpytest(*args)
+
+    out.assert_outcomes(passed=4, failed=0)
+    assert out.outlines[9:13] == [
+        "test_one.py::T::test_a PASSED",
+        "test_one.py::T::test_b PASSED",
+        "test_one.py::T::test_c PASSED",
+        "test_one.py::T::test_d PASSED",
+    ]
+
+
+def test_classes_reordered_unless_marked(ourtester):
+    ourtester.makepyfile(
+        test_one="""
+        import pytest
+
+        from unittest import TestCase
+
+
+        class A(TestCase):
+            def test_aa(self):
+                pass
+            def test_ab(self):
+                pass
+            def test_ac(self):
+                pass
+
+
+        class B(TestCase):
+            def test_ba(self):
+                pass
+            def test_bb(self):
+                pass
+            def test_bc(self):
+                pass
+
+
+        @pytest.mark.randomly_dont_reorganize
+        class C(TestCase):
+            def test_ca(self):
+                pass
+            def test_cb(self):
+                pass
+            def test_cc(self):
+                pass
+
+
+        class D(TestCase):
+            def test_da(self):
+                pass
+            def test_db(self):
+                pass
+            def test_dc(self):
+                pass
+        """
+    )
+    args = ["-v", "--randomly-seed=1"]
+
+    out = ourtester.runpytest(*args)
+
+    out.assert_outcomes(passed=12, failed=0)
+    assert out.outlines[9:21] == [
+        "test_one.py::A::test_ab PASSED",
+        "test_one.py::A::test_aa PASSED",
+        "test_one.py::A::test_ac PASSED",
+        "test_one.py::C::test_ca PASSED",
+        "test_one.py::C::test_cb PASSED",
+        "test_one.py::C::test_cc PASSED",
+        "test_one.py::B::test_bb PASSED",
+        "test_one.py::B::test_ba PASSED",
+        "test_one.py::B::test_bc PASSED",
+        "test_one.py::D::test_da PASSED",
+        "test_one.py::D::test_dc PASSED",
+        "test_one.py::D::test_db PASSED",
+    ]
+
+
 def test_test_functions_reordered(ourtester):
     ourtester.makepyfile(
         test_one="""
@@ -379,6 +480,153 @@ def test_d():
     ]
 
 
+def test_test_functions_not_reordered_if_marked(ourtester):
+    ourtester.makepyfile(
+        test_one="""
+        import pytest
+
+        pytestmark = pytest.mark.randomly_dont_reorganize
+
+
+        def test_a():
+            pass
+
+        def test_b():
+            pass
+
+        def test_c():
+            pass
+
+        def test_d():
+            pass
+        """
+    )
+    args = ["-v", "--randomly-seed=15"]
+
+    out = ourtester.runpytest(*args)
+
+    out.assert_outcomes(passed=4, failed=0)
+    assert out.outlines[9:13] == [
+        "test_one.py::test_a PASSED",
+        "test_one.py::test_b PASSED",
+        "test_one.py::test_c PASSED",
+        "test_one.py::test_d PASSED",
+    ]
+
+
+def test_test_functions_reordered_if_individual_function_is_marked(ourtester):
+    ourtester.makepyfile(
+        test_one="""
+        import pytest
+
+
+        def test_a():
+            pass
+
+        @pytest.mark.randomly_dont_reorganize
+        def test_b():
+            pass
+
+        def test_c():
+            pass
+
+        def test_d():
+            pass
+        """
+    )
+    args = ["-v", "--randomly-seed=15"]
+
+    out = ourtester.runpytest(*args)
+
+    out.assert_outcomes(passed=4, failed=0)
+    assert out.outlines[9:13] == [
+        "test_one.py::test_c PASSED",
+        "test_one.py::test_a PASSED",
+        "test_one.py::test_b PASSED",
+        "test_one.py::test_d PASSED",
+    ]
+
+
+def test_test_functions_not_reordered_if_all_functions_are_marked(ourtester):
+    ourtester.makepyfile(
+        test_one="""
+        import pytest
+
+
+        @pytest.mark.randomly_dont_reorganize
+        def test_a():
+            pass
+
+        @pytest.mark.randomly_dont_reorganize
+        def test_b():
+            pass
+
+        @pytest.mark.randomly_dont_reorganize
+        def test_c():
+            pass
+
+        @pytest.mark.randomly_dont_reorganize
+        def test_d():
+            pass
+        """
+    )
+    args = ["-v", "--randomly-seed=15"]
+
+    out = ourtester.runpytest(*args)
+
+    out.assert_outcomes(passed=4, failed=0)
+    assert out.outlines[9:13] == [
+        "test_one.py::test_a PASSED",
+        "test_one.py::test_b PASSED",
+        "test_one.py::test_c PASSED",
+        "test_one.py::test_d PASSED",
+    ]
+
+
+def test_test_files_reordered_unless_marked(ourtester):
+    code = """
+        def test_1():
+            pass
+
+        def test_2():
+            pass
+
+        def test_3():
+            pass
+    """
+    ourtester.makepyfile(
+        test_a=code,
+        test_b=code,
+        test_c=f"""
+        import pytest
+
+        pytestmark = pytest.mark.randomly_dont_reorganize
+
+        {code}
+        """,
+        test_d=code,
+    )
+    args = ["-v", "--randomly-seed=15"]
+
+    out = ourtester.runpytest(*args)
+
+    out.assert_outcomes(passed=12, failed=0)
+    assert out.outlines[9:21] == [
+        "test_b.py::test_3 PASSED",
+        "test_b.py::test_1 PASSED",
+        "test_b.py::test_2 PASSED",
+        "test_a.py::test_3 PASSED",
+        "test_a.py::test_2 PASSED",
+        "test_a.py::test_1 PASSED",
+        "test_d.py::test_3 PASSED",
+        "test_d.py::test_1 PASSED",
+        "test_d.py::test_2 PASSED",
+        "test_c.py::test_1 PASSED",
+        "test_c.py::test_2 PASSED",
+        "test_c.py::test_3 PASSED",
+    ]
+
+
 def test_test_functions_reordered_when_randomness_in_module(ourtester):
     ourtester.makepyfile(
         test_one="""