HYDRA-795 - add test to cover arnold lights (#56)

* add test to cover arnold lights

* update based on review

test/lib/mayaUsd/render/mayaToHydra/CMakeLists.txt

@@ -17,6 +17,7 @@ set(INTERACTIVE_TEST_SCRIPT_FILES
     testUSDLights.py
     testFlowViewportAPI.py
     testStageVariants.py
+    testArnoldLights.py
     cpp/testColorPreferences.py
     cpp/testCppFramework.py
     cpp/testMayaSceneFlattening.py

test/lib/mayaUsd/render/mayaToHydra/testArnoldLights.py

@@ -0,0 +1,93 @@
+#
+# Copyright 2024 Autodesk, Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import maya.cmds as cmds
+import fixturesUtils
+import mtohUtils
+import mayaUtils
+import unittest
+import platform
+
+class TestArnoldLights(mtohUtils.MtohTestCase): #Subclassing mtohUtils.MtohTestCase to be able to call self.assertSnapshotClose
+    # MayaHydraBaseTestCase.setUpClass requirement.
+    _file = __file__
+
+    @property
+    def imageDiffFailThreshold(self):
+        return 0.01
+
+    @property
+    def imageDiffFailPercent(self):
+        # Wireframes seem to have a slightly different color on macOS. We'll increase the thresholds
+        # for that platform specifically for now, so we can still catch issues on other platforms.
+        if platform.system() == "Darwin":
+            return 3
+        return 0.2
+
+    def verifyLightingModes(self, shadowOn):
+        imageSuffix = "_shadowOn" if shadowOn else ""
+        panel = mayaUtils.activeModelPanel()
+
+        #Turn on/off shadows
+        cmds.modelEditor(panel, edit=True, shadows=shadowOn)
+
+        #All Lights mode
+        cmds.modelEditor(panel, edit=True, displayLights="all")
+        cmds.refresh()
+        self.assertSnapshotClose("allLights" + imageSuffix + ".png", self.imageDiffFailThreshold, self.imageDiffFailPercent)
+
+        #TODO: Enable code below when those lighting modes are supported by arnold lights
+        #Default Light mode
+        #cmds.modelEditor(panel, edit=True, displayLights="default")
+        #cmds.refresh()
+        #self.assertSnapshotClose("defaultLight" + imageSuffix + ".png", self.imageDiffFailThreshold, self.imageDiffFailPercent)
+
+        #Selected Light mode
+        #cmds.modelEditor(panel, edit=True, displayLights="selected")
+        #cmds.select( clear=True )
+
+        #cmds.select( 'aiSkyDomeLight1', r=True )
+        #cmds.refresh()
+        #self.assertSnapshotClose("spotLight" + imageSuffix + ".png", self.imageDiffFailThreshold, self.imageDiffFailPercent)
+
+        #Flat Light mode
+        #cmds.modelEditor(panel, edit=True, displayLights="flat")
+        #cmds.refresh()
+        #self.assertSnapshotClose("flatLight" + imageSuffix + ".png", self.imageDiffFailThreshold, self.imageDiffFailPercent)
+
+        #No Light mode
+        #cmds.modelEditor(panel, edit=True, displayLights="none")
+        #cmds.refresh()
+        #self.assertSnapshotClose("noLight" + imageSuffix + ".png", self.imageDiffFailThreshold, self.imageDiffFailPercent)
+
+    #Test arnold lights (e.g., aiSkyDomeLight,etc.) with a maya native sphere and usd sphere.
+    @unittest.skipUnless(mtohUtils.checkForMayaUsdPlugin() and mtohUtils.checkForMtoAPlugin(), "Requires Maya USD and MtoA Plugins.")
+    def test_ArnoldLights(self):
+        cmds.file(new=True, force=True)
+
+        # Load a maya scene with a maya native sphere, usd sphere and some lights, with HdStorm already being the viewport renderer.
+        # The sphere is not at the origin on purpose
+        testFile = mayaUtils.openTestScene(
+                "testArnoldLights",
+                "testArnoldLights.ma")
+        cmds.refresh()
+
+        #Test Lighting Modes
+        #Shadow OFF
+        self.verifyLightingModes(False)
+
+if __name__ == '__main__':
+    fixturesUtils.runTests(globals())