Fix PlatformDetection.GetFrameworkVersion()

Author: safern

src/Common/tests/System/PlatformDetection.cs

@@ -82,21 +82,18 @@ public static Version GetFrameworkVersion()
         {
             string[] descriptionArray = RuntimeInformation.FrameworkDescription.Split(' ');
             if (descriptionArray.Length < 3)
-            {
                 return null;
-            }
-                
-            string runningVersion = descriptionArray[2];
 
-            // we could get a version with build number > 1 e.g 4.6.1375 but we only want to have 4.6.1
-            // so that we get the actual Framework Version
-            if (runningVersion.Length > 5)
+            if (!Version.TryParse(descriptionArray[2], out Version actualVersion))
+                return null;
+
+            foreach (Range currentRange in FrameworkRanges)
             {
-                runningVersion = runningVersion.Substring(0, 5);
+                if (currentRange.IsInRange(actualVersion))
+                    return currentRange.FrameworkVersion;
             }
 
-            Version result;
-            return Version.TryParse(runningVersion, out result) ? result : null;
+            return null;
         }
 
         private static int s_isWinRT = -1;
@@ -405,5 +402,33 @@ public static bool IsNonZeroLowerBoundArraySupported
         // System.Security.Cryptography.Xml.XmlDsigXsltTransform.GetOutput() relies on XslCompiledTransform which relies
         // heavily on Reflection.Emit
         public static bool IsXmlDsigXsltTransformSupported => PlatformDetection.IsReflectionEmitSupported;
+
+        public static Range[] FrameworkRanges => new Range[]{
+          new Range(new Version(4, 7, 2500, 0), null, new Version(4, 7, 1)),
+          new Range(new Version(4, 6, 2000, 0), new Version(4, 7, 2090, 0), new Version(4, 7, 0)),
+          new Range(new Version(4, 6, 1500, 0), new Version(4, 6, 1999, 0), new Version(4, 6, 2)),
+          new Range(new Version(4, 6, 1000, 0), new Version(4, 6, 1499, 0), new Version(4, 6, 1)),
+          new Range(new Version(4, 6, 55, 0), new Version(4, 6, 999, 0), new Version(4, 6, 0)),
+          new Range(new Version(4, 0, 30319, 0), new Version(4, 0, 52313, 36313), new Version(4, 5, 2))
+        };
+
+        public class Range
+        {
+            public Version Start { get; private set; }
+            public Version Finish { get; private set; }
+            public Version FrameworkVersion { get; private set; }
+
+            public Range(Version start, Version finish, Version frameworkVersion)
+            {
+                Start = start;
+                Finish = finish;
+                FrameworkVersion = frameworkVersion;
+            }
+
+            public bool IsInRange(Version version)
+            {
+                return version >= Start && (Finish == null || version <= Finish);
+            }
+        }
     }
 }