Fix FileSystemWatcher test race + wrong event name

On Linux, depending on the timing of events, we can sometimes generate
delete+create instead of rename. As such, we can't perform renames and
test that no create or delete is raised when we're running on Linux.

The issue had so far only arisen on the negative create test and not the
negative delete test, which turned out to be because the negative delete
test was using the wrong event name.

Author: nguerrera

src/System.IO.FileSystem.Watcher/tests/FileSystemWatcher.Created.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Threading;
 using Xunit;
 
@@ -101,7 +102,14 @@ public static void FileSystemWatcher_Created_Negative()
                 testFile.Flush();
 
                 // renaming a directory
-                testDir.Move(testDir.Path + "_rename");
+                //
+                // We don't do this on Linux because depending on the timing of MOVED_FROM and MOVED_TO events,
+                // a rename can trigger delete + create as a deliberate handling of an edge case, and this
+                // test is checking that no create events are raised.
+                if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                {
+                    testDir.Move(testDir.Path + "_rename");
+                }
 
                 // deleting a file & directory by leaving the using block
             }

src/System.IO.FileSystem.Watcher/tests/FileSystemWatcher.Deleted.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Threading;
 using Xunit;
 
@@ -70,9 +71,16 @@ public static void FileSystemWatcher_Deleted_Negative()
                 testFile.Flush();
 
                 // renaming a directory
-                testDir.Move(testDir.Path + "_rename");
+                //
+                // We don't do this on Linux because depending on the timing of MOVED_FROM and MOVED_TO events,
+                // a rename can trigger delete + create as a deliberate handling of an edge case, and this
+                // test is checking that no delete events are raised.
+                if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                {
+                    testDir.Move(testDir.Path + "_rename");
+                }
 
-                Utility.ExpectNoEvent(eventOccured, "changed");
+                Utility.ExpectNoEvent(eventOccured, "deleted");
             }
         }
     }