Imported Upstream version 5.20.0.180

Former-commit-id: ff953ca879339fe1e1211f7220f563e1342e66cb

external/corefx/src/System.IO/tests/BinaryWriter/BinaryWriter.WriteByteCharTests.cs

@@ -100,6 +100,8 @@ namespace System.IO.Tests
             mem.Dispose();
         }
 
+
+#if !MONO // Avoid CodePagesEncodingProvider dependency in CoreFX test assembly
         /// <summary>
         /// Cases Tested:
         /// Writing bytes casted to chars and using a different encoding; iso-2022-jp.
@@ -139,6 +141,7 @@ namespace System.IO.Tests
             writer.Dispose();
             reader.Dispose();
         }
+#endif
 
         /// <summary>
         /// Testing that bytes can be written to a stream with BinaryWriter.

external/corefx/src/System.IO/tests/MemoryStream/MemoryStream.ConstructorTests.cs

@@ -35,7 +35,9 @@ namespace System.IO.Tests
         {
             Assert.Throws<ArgumentOutOfRangeException>(() => new MemoryStream(int.MinValue));
             Assert.Throws<ArgumentOutOfRangeException>(() => new MemoryStream(-1));
+#if !MONO
             Assert.Throws<OutOfMemoryException>(() => new MemoryStream(int.MaxValue));
+#endif
         }
     }
 }

external/corefx/src/System.IO/tests/MemoryStream/MemoryStreamTests.netcoreapp.cs

@@ -63,6 +63,7 @@ namespace System.IO.Tests
         }
 
         [Fact]
+        [SkipOnTargetFramework(TargetFrameworkMonikers.Mono)] // Requires base Stream span API
         public void DerivedMemoryStream_ReadWriteSpanCalled_ReadWriteArrayUsed()
         {
             var s = new ReadWriteOverridingMemoryStream();