Tests: Add UI tests for quick effects

These tend to break when there are bugs somewhere else, as such they are
a good case to cover in higher level testing.

Rather than testing the quick effects themselves (like, testing that
they do exactly the right thing), just make sure that adding them
doesn't crash, and does roughly the right thing.

When building without fluids support, the Quick Liquid and Quick Smoke
tests won't run, but print an error. I think that is better than
failing, because it's common to build without these and the failures
would be annoying.

Pull Request: https://projects.blender.org/blender/blender/pulls/156808

tests/python/ui_simulate/test_quick_effects.py

@@ -0,0 +1,84 @@
+# SPDX-FileCopyrightText: 2025 Blender Authors
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+"""
+This file does not run anything, its methods are accessed for tests by ``run_blender_setup.py``.
+
+Does not thoroughly test the quick effects themselves (as in, testing that they apply the right
+settings), it just tests that adding them works and doesn't crash when done through the UI. This
+tends to break, indicating regressions elsewhere.
+"""
+import modules.ui_test_utils as ui
+
+
+def add_quick_fur():
+    import bpy
+
+    e, t, window = ui.test_window()
+
+    object = bpy.context.object
+    # Just a pre-condition
+    t.assertIsNotNone(object)
+
+    yield from ui.call_operator(e, "Quick Fur")
+
+    curves_object = bpy.context.object
+    t.assertIsNotNone(curves_object)
+    t.assertEqual(curves_object.type, 'CURVES')
+    # Multiple modifiers are added and reordered then. Just make sure there's at least one nodes
+    # modifier.
+    t.assertEqual(curves_object.modifiers[0].type, 'NODES')
+
+
+def add_quick_smoke():
+    import bpy
+
+    if not bpy.app.build_options.fluid:
+        print("Fluid is not enabled, skipping quick smoke test")
+
+    e, t, window = ui.test_window()
+
+    object = bpy.context.object
+    # Just a pre-condition
+    t.assertIsNotNone(object)
+
+    yield from ui.call_operator(e, "Quick Smoke")
+    t.assertEqual(object.modifiers[0].type, 'FLUID')
+    t.assertEqual(object.modifiers[0].fluid_type, 'FLOW')
+    t.assertEqual(object.modifiers[0].flow_settings.flow_type, 'SMOKE')
+
+
+def add_quick_liquid():
+    import bpy
+
+    if not bpy.app.build_options.fluid:
+        print("Fluid is not enabled, skipping quick liquid test")
+
+    e, t, window = ui.test_window()
+
+    object = bpy.context.object
+    # Just a pre-condition
+    t.assertIsNotNone(object)
+
+    yield from ui.call_operator(e, "Quick Liquid")
+    t.assertEqual(object.modifiers[0].type, 'FLUID')
+    t.assertEqual(object.modifiers[0].flow_settings.flow_type, 'LIQUID')
+
+
+def add_quick_explode():
+    import bpy
+
+    e, t, window = ui.test_window()
+
+    object = bpy.context.object
+    # Just a pre-condition
+    t.assertIsNotNone(object)
+
+    yield from ui.call_operator(e, "Quick Explode")
+    t.assertEqual(object.modifiers[0].type, 'PARTICLE_SYSTEM')
+    t.assertEqual(object.modifiers[1].type, 'EXPLODE')
+
+    # Just start and stop the animation.
+    yield from ui.call_operator(e, "Play Animation")
+    yield from ui.call_operator(e, "Play Animation")