diff --git a/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/File/Copy.cs b/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/File/Copy.cs
index d58fd95cfae3d..7abc7ac3a286e 100644
--- a/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/File/Copy.cs
+++ b/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/File/Copy.cs
@@ -5,6 +5,7 @@
 using System.Linq;
 using System.Security.Cryptography;
 using Xunit;
+using Xunit.Abstractions;
 
 namespace System.IO.Tests
 {
@@ -236,6 +237,17 @@ public void WindowsAlternateDataStream(string defaultStream, string alternateStr
             File.WriteAllText(testFile2DefaultStream, "Bar");
             Assert.Throws<IOException>(() => Copy(testFile2DefaultStream, testFileAlternateStream));
 
+            try
+            {
+                Copy(testFile2DefaultStream, testFileAlternateStream);
+                Assert.Fail();
+            }
+            catch (IOException e)
+            {
+                // Error code for "the file exists".
+                Assert.Equal(-2147024816, e.HResult);
+            }
+
             // This always throws as you can't copy an alternate stream out (oddly)
             Assert.Throws<IOException>(() => Copy(testFileAlternateStream, testFile2));
             Assert.Throws<IOException>(() => Copy(testFileAlternateStream, testFile2 + alternateStream));
@@ -275,6 +287,12 @@ public void OverwriteCopyOntoLink()
 
     public class File_Copy_str_str_b : File_Copy_str_str
     {
+        private ITestOutputHelper _output;
+        public File_Copy_str_str_b(ITestOutputHelper output)
+        {
+            _output = output;
+        }
+
         protected override void Copy(string source, string dest)
         {
             File.Copy(source, dest, false);
@@ -352,6 +370,8 @@ public void WindowsAlternateDataStreamOverwrite(string defaultStream, string alt
 
             // Copy the default stream into an alternate stream
             File.WriteAllText(testFileDefaultStream, "Foo");
+            Assert.Equal("Foo", File.ReadAllText(testFileDefaultStream));
+            _output.WriteLine("Copying default stream into alternate stream.");
             Copy(testFileDefaultStream, testFileAlternateStream);
             Assert.Equal(testFile, testDirectory.GetFiles().Single().FullName);
             Assert.Equal("Foo", File.ReadAllText(testFileDefaultStream));
@@ -361,6 +381,11 @@ public void WindowsAlternateDataStreamOverwrite(string defaultStream, string alt
             string testFile2 = Path.Combine(testDirectory.FullName, GetTestFileName());
             string testFile2DefaultStream = testFile2 + defaultStream;
             File.WriteAllText(testFile2DefaultStream, "Bar");
+            Assert.Equal("Bar", File.ReadAllText(testFile2DefaultStream));
+            Assert.Equal("Foo", File.ReadAllText(testFileAlternateStream));
+            _output.WriteLine($"Attributes for '{testFile2DefaultStream}': {File.GetAttributes(testFile2DefaultStream)}");
+            _output.WriteLine($"Attributes for '{testFileAlternateStream}': {File.GetAttributes(testFileAlternateStream)}");
+            _output.WriteLine("Overwriting alternate stream.");
             Copy(testFile2DefaultStream, testFileAlternateStream, overwrite: true);
             Assert.Equal("Foo", File.ReadAllText(testFileDefaultStream));
             Assert.Equal("Bar", File.ReadAllText(testFileAlternateStream));
diff --git a/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/FileInfo/CopyTo.cs b/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/FileInfo/CopyTo.cs
index 49625c1f0c193..1899a98fea411 100644
--- a/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/FileInfo/CopyTo.cs
+++ b/src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/FileInfo/CopyTo.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Xunit;
+using Xunit.Abstractions;
 
 namespace System.IO.Tests
 {
@@ -16,6 +17,11 @@ protected override void Copy(string source, string dest)
 
     public class FileInfo_CopyTo_str_b : File_Copy_str_str_b
     {
+        public FileInfo_CopyTo_str_b(ITestOutputHelper output)
+            : base(output)
+        {
+        }
+
         protected override void Copy(string source, string dest)
         {
             new FileInfo(source).CopyTo(dest, false);