tested to check if parameter targets are applied correctly

com.unity.perception/Editor/Randomization/ParameterElement.cs

             m_TargetGameObjectProperty = m_SerializedProperty.FindPropertyRelative("target.gameObject");
             ToggleTargetContainer();
 
-            var frequencyField = this.Q<PropertyField>("application-frequency");
+            var frequencyField = this.Q<EnumField>("application-frequency");
             frequencyField.BindProperty(m_SerializedProperty.FindPropertyRelative("target.applicationFrequency"));
 
             var targetField = this.Q<PropertyField>("target");

com.unity.perception/Editor/Randomization/Uxml/ParameterElement.uxml

                             <Label text="Target Property" class="unity-base-field__label"/>
                             <editor:ToolbarMenu text="Select A Property" name="property-select-menu" class="property-select-menu"/>
                         </VisualElement>
-                        <editor:PropertyField name="application-frequency"/>
+                        <editor:EnumField label="Application Frequency" name="application-frequency"/>
                     </VisualElement>
                 </Box>
                 <Box name="extra-properties" style="padding-left: 4px; border-top-width: 0px;"/>

com.unity.perception/Runtime/Randomization/Parameters/Parameter.cs

         /// <summary>
         /// The target this parameter apply a sample to
         /// </summary>
-        [HideInInspector, SerializeField] internal ParameterTarget target = new ParameterTarget();
+        [HideInInspector, SerializeField] public ParameterTarget target = new ParameterTarget();
-
-        // /// <summary>
-        // /// Returns meta information regarding this type of parameter
-        // /// </summary>
-        // internal ParameterDisplayName displayName =>
-        //     (ParameterDisplayName)Attribute.GetCustomAttribute(GetType(), typeof(ParameterDisplayName));
 
         /// <summary>
         /// The sample type generated by this parameter

com.unity.perception/Runtime/Randomization/Parameters/ParameterTarget.cs

     /// Typically managed by a parameter configuration.
     /// </summary>
     [Serializable]
-    class ParameterTarget
+    public class ParameterTarget
-        public GameObject gameObject;
-        public Component component;
-        public string propertyName = "";
-        public FieldOrProperty fieldOrProperty;
-        public ParameterApplicationFrequency applicationFrequency;
+        [SerializeField] internal GameObject gameObject;
+        [SerializeField] internal Component component;
+        [SerializeField] internal string propertyName = "";
+        [SerializeField] internal FieldOrProperty fieldOrProperty;
+        [SerializeField] internal ParameterApplicationFrequency applicationFrequency;
+        /// <summary>
+        /// Assigns a new target
+        /// </summary>
+        /// <param name="targetObject">The target GameObject</param>
+        /// <param name="targetComponent">The target component on the target GameObject</param>
+        /// <param name="fieldOrPropertyName">The name of the property to apply the parameter to</param>
+        /// <param name="frequency">How often to apply the parameter to its target</param>
-            GameObject obj, Component comp, string fieldOrPropertyName, ParameterApplicationFrequency frequency)
+            GameObject targetObject,
+            Component targetComponent,
+            string fieldOrPropertyName,
+            ParameterApplicationFrequency frequency)
-            gameObject = obj;
-            component = comp;
+            gameObject = targetObject;
+            component = targetComponent;
             propertyName = fieldOrPropertyName;
             applicationFrequency = frequency;
             var componentType = component.GetType();
         }
 
-        public void Clear()
+        internal void Clear()
         {
             gameObject = null;
             component = null;
-        /// <summary>
-        /// Writes a sampled value to the target GameObject and property
-        /// </summary>
-        public void ApplyValueToTarget(object value)
+        internal void ApplyValueToTarget(object value)
         {
             var componentType = component.GetType();
             if (fieldOrProperty == FieldOrProperty.Field)
         }
     }
 
-    enum ParameterApplicationFrequency
+    /// <summary>
+    /// How often to apply a new sample to a parameter's target
+    /// </summary>
+    public enum ParameterApplicationFrequency
     {
         OnIterationSetup,
         EveryFrame

com.unity.perception/Runtime/Randomization/Scenarios/ScenarioBase.cs

     public abstract class ScenarioBase : MonoBehaviour
     {
         static ScenarioBase s_ActiveScenario;
+        bool m_FirstFrame = true;
 
         /// <summary>
         /// If true, this scenario will quit the Unity application when it's finished executing
         public virtual void OnInitialize() { }
 
         /// <summary>
-        /// Called when each scenario iteration starts
+        /// Called at the beginning of every scenario iteration
         /// </summary>
         public virtual void OnIterationSetup() { }
 
         public virtual void OnFrameStart() { }
 
         /// <summary>
-        /// Called right before the scenario iterates
+        /// Called the frame after an iteration ends
         /// </summary>
         public virtual void OnIterationTeardown() { }
 
             s_ActiveScenario = null;
         }
 
-        IEnumerator Start()
+        void Start()
         {
             if (deserializeOnStart)
                 Deserialize();
-            // TODO: remove this yield when the perception camera no longer skips the first frame of the simulation
-            yield return null;
+            if (currentIterationFrame == 0 && !m_FirstFrame)
+                OnIterationTeardown();
+
             if (isScenarioComplete)
             {
                 OnComplete();
                 return;
             }
 
-            if (isIterationComplete)
-            {
-                currentIteration++;
-                currentIterationFrame = 0;
-                OnIterationTeardown();
-            }
-
             if (currentIterationFrame == 0)
             {
                 DatasetCapture.StartNewSequence();
             foreach (var config in ParameterConfiguration.configurations)
                 config.ApplyParameters(framesSinceInitialization, ParameterApplicationFrequency.EveryFrame);
             OnFrameStart();
+        }
+
+        void LateUpdate()
+        {
+            if (isIterationComplete)
+            {
+                currentIteration++;
+                currentIterationFrame = 0;
+            }
+            m_FirstFrame = false;
         }
     }
 }

com.unity.perception/Tests/Runtime/Randomization/ScenarioTests.cs

             Object.DestroyImmediate(m_TestObject);
         }
 
-        IEnumerator CreateNewScenario()
+        void CreateNewScenario()
-            yield return null;
-            yield return CreateNewScenario();
+            CreateNewScenario();
             m_Scenario.serializedConstantsFileName = "perception_serialization_test";
 
             var constants = new FixedLengthScenario.Constants
         [UnityTest]
         public IEnumerator IterationsCanLastMultipleFrames()
         {
-            yield return CreateNewScenario();
+            CreateNewScenario();
-
-            // Scenario update loop starts next frame
-            yield return null;
 
             for (var i = 0; i < testIterationFrameCount; i++)
             {
         }
 
         [UnityTest]
-        public IEnumerator CompletesWhenIsScenarioCompleteIsTrue()
+        public IEnumerator FinishesWhenIsScenarioCompleteIsTrue()
-            yield return CreateNewScenario();
+            CreateNewScenario();
-
-            // Scenario update loop starts next frame
-            yield return null;
 
             for (var i = 0; i < testIterationTotal; i++)
             {
         [UnityTest]
         public IEnumerator AppliesParametersEveryFrame()
         {
-            yield return CreateNewScenario();
+            CreateNewScenario();
             m_Scenario.constants.framesPerIteration = 5;
             m_Scenario.constants.totalIterations = 1;
 
         [UnityTest]
         public IEnumerator AppliesParametersEveryIteration()
         {
-            yield return CreateNewScenario();
-            m_Scenario.constants.framesPerIteration = 5;
-            m_Scenario.constants.totalIterations = 1;
-
             var config = m_TestObject.AddComponent<ParameterConfiguration>();
             var parameter = config.AddParameter<Vector3Parameter>();
             parameter.x = new UniformSampler(1, 2);
-            var transform = m_Scenario.transform;
+            var transform = m_TestObject.transform;
+            transform.position = new Vector3();
-            var initialPosition = new Vector3();
-            transform.position = initialPosition;
+            yield return new WaitForEndOfFrame();
+            CreateNewScenario();
+            m_Scenario.constants.framesPerIteration = 2;
+            m_Scenario.constants.totalIterations = 2;
+
+            yield return new WaitForEndOfFrame();
+            var initialPosition = transform.position;
+            Assert.AreNotEqual(new Vector3(), initialPosition);
-            // The position should change when the first iteration starts
-            yield return null;
-            Assert.AreNotEqual(initialPosition, transform.position);
+            yield return new WaitForEndOfFrame();
-            initialPosition = transform.position;
+            var nextPosition = transform.position;
+            Assert.AreEqual(initialPosition, nextPosition);
-            // The position should stay the same since the iteration doesn't change for another 4 frames
-            yield return null;
+            yield return new WaitForEndOfFrame();
-            Assert.AreEqual(initialPosition, transform.position);
+            Assert.AreNotEqual(nextPosition, transform.position);
-            yield return CreateNewScenario();
+            CreateNewScenario();
             m_Scenario.constants.framesPerIteration = 2;
             m_Scenario.constants.totalIterations = 2;