Relax tolerance for .NET Core 2.x

Author: JimBobSquarePants

tests/ImageSharp.Drawing.Tests/Drawing/Text/DrawTextOnImageTests.cs

@@ -23,8 +23,8 @@ public class DrawTextOnImageTests
 
         private const string TestText = "Sphinx of black quartz, judge my vow\n0123456789";
 
-        private static readonly ImageComparer TextDrawingComparer = TestEnvironment.IsFramework
-            ? ImageComparer.TolerantPercentage(1e-3f) // Relax comparison on .NET Framework
+        private static readonly ImageComparer TextDrawingComparer = TestEnvironment.IsFramework || TestEnvironment.NetCoreVersion.StartsWith("2")
+            ? ImageComparer.TolerantPercentage(1e-3f) // Relax comparison on .NET Framework and .NET Core 2.x
             : ImageComparer.TolerantPercentage(1e-5f);
 
         private static readonly ImageComparer OutlinedTextDrawingComparer = ImageComparer.TolerantPercentage(5e-4f);

tests/ImageSharp.Drawing.Tests/TestUtilities/TestEnvironment.cs

@@ -24,8 +24,15 @@ public static partial class TestEnvironment
 
         private static readonly Lazy<string> SolutionDirectoryFullPathLazy = new Lazy<string>(GetSolutionDirectoryFullPathImpl);
 
+        private static readonly Lazy<string> NetCoreVersionLazy = new Lazy<string>(GetNetCoreVersion);
+
         internal static bool IsFramework => RuntimeInformation.FrameworkDescription.StartsWith(".NET Framework");
 
+        /// <summary>
+        /// Gets the .NET Core version, if running on .NET Core, otherwise returns an empty string.
+        /// </summary>
+        internal static string NetCoreVersion => NetCoreVersionLazy.Value;
+
         /// <summary>
         /// Gets a value indicating whether test execution runs on CI.
         /// </summary>
@@ -132,5 +139,22 @@ internal static string CreateOutputDirectory(string path, params string[] pathPa
 
             return path;
         }
+
+        /// <summary>
+        /// Solution borrowed from:
+        /// https://github.com/dotnet/BenchmarkDotNet/issues/448#issuecomment-308424100
+        /// </summary>
+        private static string GetNetCoreVersion()
+        {
+            Assembly assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;
+            string[] assemblyPath = assembly.Location.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);
+            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");
+            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)
+            {
+                return assemblyPath[netCoreAppIndex + 1];
+            }
+
+            return string.Empty;
+        }
     }
 }