Fixed Stepper handler broken tests

Author: jsuarezruiz

src/Core/src/Platform/iOS/StepperExtensions.cs

@@ -16,7 +16,10 @@ public static void UpdateMaximum(this UIStepper nativeStepper, IStepper stepper)
 
 		public static void UpdateIncrement(this UIStepper nativeStepper, IStepper stepper)
 		{
-			nativeStepper.StepValue = stepper.Increment;
+			var increment = stepper.Increment;
+
+			if (increment > 0)
+				nativeStepper.StepValue = stepper.Increment;
 		}
 
 		public static void UpdateValue(this UIStepper nativeStepper, IStepper stepper)

src/Core/tests/DeviceTests/Handlers/Stepper/StepperHandlerTests.cs

@@ -30,6 +30,7 @@ public async Task MaximumInitializesCorrectly()
 		{
 			var stepper = new StepperStub()
 			{
+				Minimum = 0,
 				Maximum = 50
 			};
 
@@ -41,7 +42,8 @@ public async Task MinimumInitializesCorrectly()
 		{
 			var stepper = new StepperStub()
 			{
-				Minimum = 10
+				Minimum = 10,
+				Maximum = 50
 			};
 
 			await ValidatePropertyInitValue(stepper, () => stepper.Minimum, GetNativeMinimum, stepper.Minimum);