Remove 3 active issues (#59790)

* Remove 3 active issues

* Apply suggestions from code review

Co-authored-by: Stephen Toub <stoub@microsoft.com>

Co-authored-by: Stephen Toub <stoub@microsoft.com>

Author: danmoseley

src/libraries/System.IO.FileSystem/tests/Base/InfoGetSetTimes.cs

@@ -11,23 +11,6 @@ public abstract class InfoGetSetTimes<T> : BaseGetSetTimes<T> where T : FileSyst
     {
         protected abstract void InvokeCreate(T item);
 
-        [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/30108")]
-        public void DoesntExistThenCreate_ReturnsDefaultValues()
-        {
-            T item = GetMissingItem();
-            InvokeCreate(item);
-
-            Assert.All(TimeFunctions(), (function) =>
-            {
-                Assert.Equal(
-                    function.Kind == DateTimeKind.Local
-                        ? DateTime.FromFileTime(0).Ticks
-                        : DateTime.FromFileTimeUtc(0).Ticks,
-                    function.Getter(item).Ticks);
-            });
-        }
-
         [Fact]
         public void ExistsThenDelete_ReturnsDefaultValues()
         {

src/libraries/System.IO.FileSystem/tests/Directory/EnumerableTests.cs

@@ -11,7 +11,10 @@ namespace System.IO.Tests
     public class EnumerableTests : FileSystemTest
     {
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/24295", TestPlatforms.AnyUnix)]
+        // we don't guarantee thread safety of enumerators in general, but on Windows we
+        // currently are thread safe, and this test will help ensure that if we change that
+        // it's a conscious decision. Discussed in https://github.com/dotnet/runtime/issues/24295.
+        [PlatformSpecific(TestPlatforms.Windows)]
         public void FileEnumeratorIsThreadSafe()
         {
             string directory = Directory.CreateDirectory(GetTestFilePath()).FullName;

src/libraries/System.IO.FileSystem/tests/File/GetSetTimes.cs

@@ -148,7 +148,8 @@ public void SetUptoNanoseconds()
             Assert.Equal(ticks, dateTime.Ticks);
         }
 
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/43166", TestPlatforms.Linux)]
+        // Linux kernels no longer have long max date time support. Discussed in https://github.com/dotnet/runtime/issues/43166.
+        [PlatformSpecific(~TestPlatforms.Linux)]
         [ConditionalFact(nameof(SupportsLongMaxDateTime))]
         public void SetDateTimeMax()
         {