Don't coerce values until initialized.

Fixes #2372.

src/Avalonia.Controls/Primitives/RangeBase.cs

@@ -75,10 +75,18 @@ namespace Avalonia.Controls.Primitives
 
             set
             {
-                value = ValidateMinimum(value);
-                SetAndRaise(MinimumProperty, ref _minimum, value);
-                Maximum = ValidateMaximum(Maximum);
-                Value = ValidateValue(Value);
+                ValidateDouble(value, "Minimum");
+
+                if (IsInitialized)
+                {
+                    SetAndRaise(MinimumProperty, ref _minimum, value);
+                    Maximum = ValidateMaximum(Maximum);
+                    Value = ValidateValue(Value);
+                }
+                else
+                {
+                    SetAndRaise(MinimumProperty, ref _minimum, value);
+                }
             }
         }
 
@@ -94,9 +102,18 @@ namespace Avalonia.Controls.Primitives
 
             set
             {
-                value = ValidateMaximum(value);
-                SetAndRaise(MaximumProperty, ref _maximum, value);
-                Value = ValidateValue(Value);
+                ValidateDouble(value, "Maximum");
+
+                if (IsInitialized)
+                {
+                    value = ValidateMaximum(value);
+                    SetAndRaise(MaximumProperty, ref _maximum, value);
+                    Value = ValidateValue(Value);
+                }
+                else
+                {
+                    SetAndRaise(MaximumProperty, ref _maximum, value);
+                }
             }
         }
 
@@ -112,8 +129,17 @@ namespace Avalonia.Controls.Primitives
 
             set
             {
-                value = ValidateValue(value);
-                SetAndRaise(ValueProperty, ref _value, value);
+                ValidateDouble(value, "Value");
+
+                if (IsInitialized)
+                {
+                    value = ValidateValue(value);
+                    SetAndRaise(ValueProperty, ref _value, value);
+                }
+                else
+                {
+                    SetAndRaise(ValueProperty, ref _value, value);
+                }
             }
         }
 
@@ -129,6 +155,14 @@ namespace Avalonia.Controls.Primitives
             set => SetValue(LargeChangeProperty, value);
         }
 
+        protected override void OnInitialized()
+        {
+            base.OnInitialized();
+
+            Maximum = ValidateMaximum(Maximum);
+            Value = ValidateValue(Value);
+        }
+
         /// <summary>
         /// Throws an exception if the double value is NaN or Inf.
         /// </summary>
@@ -142,17 +176,6 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
-        /// <summary>
-        /// Validates the <see cref="Minimum"/> property.
-        /// </summary>
-        /// <param name="value">The value.</param>
-        /// <returns>The coerced value.</returns>
-        private double ValidateMinimum(double value)
-        {
-            ValidateDouble(value, "Minimum");
-            return value;
-        }
-
         /// <summary>
         /// Validates/coerces the <see cref="Maximum"/> property.
         /// </summary>
@@ -160,7 +183,6 @@ namespace Avalonia.Controls.Primitives
         /// <returns>The coerced value.</returns>
         private double ValidateMaximum(double value)
         {
-            ValidateDouble(value, "Maximum");
             return Math.Max(value, Minimum);
         }
 
@@ -171,7 +193,6 @@ namespace Avalonia.Controls.Primitives
         /// <returns>The coerced value.</returns>
         private double ValidateValue(double value)
         {
-            ValidateDouble(value, "Value");
             return MathUtilities.Clamp(value, Minimum, Maximum);
         }
     }

tests/Avalonia.Controls.UnitTests/Primitives/RangeBaseTests.cs

@@ -23,6 +23,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Minimum = 100,
                 Maximum = 50,
             };
+            var root = new TestRoot(target);
 
             Assert.Equal(100, target.Minimum);
             Assert.Equal(100, target.Maximum);
@@ -37,6 +38,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Maximum = 50,
                 Value = 100,
             };
+            var root = new TestRoot(target);
 
             Assert.Equal(0, target.Minimum);
             Assert.Equal(50, target.Maximum);
@@ -52,6 +54,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Maximum = 100,
                 Value = 50,
             };
+            var root = new TestRoot(target);
 
             target.Minimum = 200;
 
@@ -69,6 +72,7 @@ namespace Avalonia.Controls.UnitTests.Primitives
                 Maximum = 100,
                 Value = 100,
             };
+            var root = new TestRoot(target);
 
             target.Maximum = 50;