Change RoutePattern to not throw when inline and arg default value are the same (#747) (#748)

src/Microsoft.AspNetCore.Routing/Patterns/RoutePatternFactory.cs

@@ -343,7 +343,7 @@ namespace Microsoft.AspNetCore.Routing.Patterns
 
                 if (updatedDefaults.TryGetValue(parameter.Name, out var newDefault))
                 {
-                    if (parameter.Default != null)
+                    if (parameter.Default != null && !Equals(newDefault, parameter.Default))
                     {
                         var message = Resources.FormatTemplateRoute_CannotHaveDefaultValueSpecifiedInlineAndExplicitly(parameter.Name);
                         throw new InvalidOperationException(message);
@@ -360,7 +360,7 @@ namespace Microsoft.AspNetCore.Routing.Patterns
 
                 if (parameter.Default != null)
                 {
-                    updatedDefaults.Add(parameter.Name, parameter.Default);
+                    updatedDefaults[parameter.Name] = parameter.Default;
                 }
 
                 if (!updatedParameterPolicies.TryGetValue(parameter.Name, out var parameterConstraints) &&

test/Microsoft.AspNetCore.Routing.Tests/Patterns/RoutePatternFactoryTest.cs

@@ -66,7 +66,7 @@ namespace Microsoft.AspNetCore.Routing.Patterns
         }
 
         [Fact]
-        public void Pattern_DuplicateDefaultValue_Throws()
+        public void Pattern_DifferentDuplicateDefaultValue_Throws()
         {
             // Arrange
             var template = "{a=13}/{b}/{c}";
@@ -90,6 +90,29 @@ namespace Microsoft.AspNetCore.Routing.Patterns
                 ex.Message);
         }
 
+        [Fact]
+        public void Pattern_SameDuplicateDefaultValue()
+        {
+            // Arrange
+            var template = "{a=13}/{b}/{c}";
+            var defaults = new { a = "13", };
+            var constraints = new { };
+
+            var original = RoutePatternFactory.Parse(template);
+
+            // Act
+            var actual = RoutePatternFactory.Pattern(
+                original.RawText,
+                defaults,
+                constraints,
+                original.PathSegments);
+
+            // Assert
+            Assert.Collection(
+                actual.Defaults,
+                kvp => { Assert.Equal("a", kvp.Key); Assert.Equal("13", kvp.Value); });
+        }
+
         [Fact]
         public void Pattern_OptionalParameterDefaultValue_Throws()
         {