Add display requirement marker for tests needing a GUI and update relevant tests

Author: PierreRaybaut

plotpy/tests/conftest.py

@@ -33,10 +33,22 @@ def pytest_addoption(parser):
 
 def pytest_configure(config):
     """Configure pytest based on command line options."""
+    config.addinivalue_line(
+        "markers",
+        "requires_display: mark test as requiring a display "
+        "(skipped in offscreen mode)",
+    )
     if not config.getoption("--show-windows"):
         os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
 
 
+def pytest_runtest_setup(item):
+    """Run setup before each test."""
+    if "requires_display" in item.keywords:
+        if os.environ.get("QT_QPA_PLATFORM") == "offscreen":
+            pytest.skip("Skipped in offscreen mode (requires display)")
+
+
 @pytest.fixture(scope="session", autouse=True)
 def disable_gc_for_tests():
     """Disable garbage collection for all tests in the session."""

plotpy/tests/unit/test_manipulate_selection.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import os
 from typing import TYPE_CHECKING, Callable, TypeVar
 
 import numpy as np
@@ -269,7 +268,7 @@ def test_select_all_items():
         exec_dialog(win)
 
 
-@pytest.mark.skipif(os.name != "nt", reason="Only tested on Windows.")
+@pytest.mark.requires_display
 def test_rotate_with_mouse():
     """Test rotating an image item with the mouse."""
     with qt_app_context(exec_loop=False):
@@ -320,7 +319,7 @@ def test_rectangular_selection():
         exec_dialog(win)
 
 
-@pytest.mark.skipif(os.name != "nt", reason="Only tested on Windows.")
+@pytest.mark.requires_display
 @pytest.mark.parametrize(
     "mouse_path, rotation",
     [