Fix XmlSerializer timespan tests for any full framework version (#19564)

Author: safern

src/System.Private.Xml/tests/XmlSerializer/XmlSerializerTests.cs

@@ -27,11 +27,13 @@ static XmlSerializerTests()
         {
             MethodInfo method = typeof(XmlSerializer).GetMethod(SerializationModeSetterName, BindingFlags.NonPublic | BindingFlags.Static);
             Assert.True(method != null, $"No method named {SerializationModeSetterName}");
-            method.Invoke(null, new object[] { 1 });    
+            method.Invoke(null, new object[] { 1 });
         }
     }
-
 #endif
+
+    private static bool IsTimeSpanSerializationAvailable => !PlatformDetection.IsFullFramework || (AppContext.TryGetSwitch("Switch.System.Xml.EnableTimeSpanSerialization", out bool result) && result);
+
     [Fact]
     public static void Xml_BoolAsRoot()
     {
@@ -139,7 +141,7 @@ public static void Xml_TypeWithDateTimePropertyAsXmlTime()
             Value = new DateTime(549269870000L, DateTimeKind.Utc)
         };
 
-        if (!PlatformDetection.IsFullFramework || PlatformDetection.IsNetfx462OrNewer())
+        if (IsTimeSpanSerializationAvailable)
         {
             TypeWithDateTimePropertyAsXmlTime utcTimeRoundTrip = SerializeAndDeserialize(utcTimeOjbect,
     @"<?xml version=""1.0"" encoding=""utf-8""?>
@@ -1632,54 +1634,45 @@ public static void Xml_DifferentSerializeDeserializeOverloads()
         }
     }
 
-    [Fact]
+    [ConditionalFact(nameof(IsTimeSpanSerializationAvailable))]
     public static void Xml_TimeSpanAsRoot()
     {
-        if (!PlatformDetection.IsFullFramework || PlatformDetection.IsNetfx470OrNewer())
-        {
-            Assert.StrictEqual(new TimeSpan(1, 2, 3), SerializeAndDeserialize<TimeSpan>(new TimeSpan(1, 2, 3),
-    @"<?xml version=""1.0"" encoding=""utf-8""?>
+        Assert.StrictEqual(new TimeSpan(1, 2, 3), SerializeAndDeserialize<TimeSpan>(new TimeSpan(1, 2, 3),
+@"<?xml version=""1.0"" encoding=""utf-8""?>
 <TimeSpan>PT1H2M3S</TimeSpan>"));
-            Assert.StrictEqual(TimeSpan.Zero, SerializeAndDeserialize<TimeSpan>(TimeSpan.Zero,
-    @"<?xml version=""1.0"" encoding=""utf-8""?>
+        Assert.StrictEqual(TimeSpan.Zero, SerializeAndDeserialize<TimeSpan>(TimeSpan.Zero,
+@"<?xml version=""1.0"" encoding=""utf-8""?>
 <TimeSpan>PT0S</TimeSpan>"));
-            Assert.StrictEqual(TimeSpan.MinValue, SerializeAndDeserialize<TimeSpan>(TimeSpan.MinValue,
-    @"<?xml version=""1.0"" encoding=""utf-8""?>
+        Assert.StrictEqual(TimeSpan.MinValue, SerializeAndDeserialize<TimeSpan>(TimeSpan.MinValue,
+@"<?xml version=""1.0"" encoding=""utf-8""?>
 <TimeSpan>-P10675199DT2H48M5.4775808S</TimeSpan>"));
-            Assert.StrictEqual(TimeSpan.MaxValue, SerializeAndDeserialize<TimeSpan>(TimeSpan.MaxValue,
-    @"<?xml version=""1.0"" encoding=""utf-8""?>
+        Assert.StrictEqual(TimeSpan.MaxValue, SerializeAndDeserialize<TimeSpan>(TimeSpan.MaxValue,
+@"<?xml version=""1.0"" encoding=""utf-8""?>
 <TimeSpan>P10675199DT2H48M5.4775807S</TimeSpan>"));
-        }
     }
 
-    [Fact]
+    [ConditionalFact(nameof(IsTimeSpanSerializationAvailable))]
     public static void Xml_TypeWithTimeSpanProperty()
     {
-        if (!PlatformDetection.IsFullFramework || PlatformDetection.IsNetfx470OrNewer())
-        {
-            var obj = new TypeWithTimeSpanProperty { TimeSpanProperty = TimeSpan.FromMilliseconds(1) };
-            var deserializedObj = SerializeAndDeserialize(obj,
+        var obj = new TypeWithTimeSpanProperty { TimeSpanProperty = TimeSpan.FromMilliseconds(1) };
+        var deserializedObj = SerializeAndDeserialize(obj,
 @"<?xml version=""1.0"" encoding=""utf-16""?>
 <TypeWithTimeSpanProperty xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"">
-  <TimeSpanProperty>PT0.001S</TimeSpanProperty>
+<TimeSpanProperty>PT0.001S</TimeSpanProperty>
 </TypeWithTimeSpanProperty>");
-            Assert.StrictEqual(obj.TimeSpanProperty, deserializedObj.TimeSpanProperty);
-        }
+        Assert.StrictEqual(obj.TimeSpanProperty, deserializedObj.TimeSpanProperty);
     }
 
-    [Fact]
+    [ConditionalFact(nameof(IsTimeSpanSerializationAvailable))]
     public static void Xml_TypeWithDefaultTimeSpanProperty()
     {
-        if (!PlatformDetection.IsFullFramework || PlatformDetection.IsNetfx470OrNewer())
-        {
-            var obj = new TypeWithDefaultTimeSpanProperty { TimeSpanProperty2 = new TimeSpan(0, 1, 0) };
-            var deserializedObj = SerializeAndDeserialize(obj,
-    @"<?xml version=""1.0""?>
+        var obj = new TypeWithDefaultTimeSpanProperty { TimeSpanProperty2 = new TimeSpan(0, 1, 0) };
+        var deserializedObj = SerializeAndDeserialize(obj,
+@"<?xml version=""1.0""?>
 <TypeWithDefaultTimeSpanProperty xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema""><TimeSpanProperty2>PT1M</TimeSpanProperty2></TypeWithDefaultTimeSpanProperty>");
-            Assert.NotNull(deserializedObj);
-            Assert.Equal(obj.TimeSpanProperty, deserializedObj.TimeSpanProperty);
-            Assert.Equal(obj.TimeSpanProperty2, deserializedObj.TimeSpanProperty2);
-        }
+        Assert.NotNull(deserializedObj);
+        Assert.Equal(obj.TimeSpanProperty, deserializedObj.TimeSpanProperty);
+        Assert.Equal(obj.TimeSpanProperty2, deserializedObj.TimeSpanProperty2);
     }
 
     [Fact]