diff --git a/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
index 4e6dc36dcc..f85bc78fc0 100644
--- a/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs
@@ -19,7 +19,6 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Bmp
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Bmp")]
     public class BmpDecoderTests
     {
diff --git a/tests/ImageSharp.Tests/Formats/Bmp/BmpEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Bmp/BmpEncoderTests.cs
index d645f0b607..073cf5fcf2 100644
--- a/tests/ImageSharp.Tests/Formats/Bmp/BmpEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Bmp/BmpEncoderTests.cs
@@ -17,19 +17,18 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Bmp
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Bmp")]
     public class BmpEncoderTests
     {
         public static readonly TheoryData<BmpBitsPerPixel> BitsPerPixel =
-        new TheoryData<BmpBitsPerPixel>
+        new()
         {
             BmpBitsPerPixel.Pixel24,
             BmpBitsPerPixel.Pixel32
         };
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
-        new TheoryData<string, int, int, PixelResolutionUnit>
+        new()
         {
             { Car, 3780, 3780, PixelResolutionUnit.PixelsPerMeter },
             { V5Header, 3780, 3780, PixelResolutionUnit.PixelsPerMeter },
@@ -37,7 +36,7 @@ public class BmpEncoderTests
         };
 
         public static readonly TheoryData<string, BmpBitsPerPixel> BmpBitsPerPixelFiles =
-        new TheoryData<string, BmpBitsPerPixel>
+        new()
         {
             { Bit1, BmpBitsPerPixel.Pixel1 },
             { Bit4, BmpBitsPerPixel.Pixel4 },
diff --git a/tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs b/tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs
index b9878377df..5a8425c1fe 100644
--- a/tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs
+++ b/tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs
@@ -8,7 +8,6 @@
 using System.Reflection;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Png;
-using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Quantization;
@@ -16,7 +15,6 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats
 {
-    [Collection("RunSerial")]
     public class GeneralFormatTests
     {
         /// <summary>
@@ -34,7 +32,7 @@ public class GeneralFormatTests
         /// <summary>
         /// The collection of image files to test against.
         /// </summary>
-        protected static readonly List<TestFile> Files = new List<TestFile>
+        protected static readonly List<TestFile> Files = new()
         {
             TestFile.Create(TestImages.Jpeg.Baseline.Calliphora),
             TestFile.Create(TestImages.Bmp.Car),
@@ -85,8 +83,8 @@ public void DecodeThenEncodeImageFromStreamShouldSucceed()
         }
 
         public static readonly TheoryData<string> QuantizerNames =
-            new TheoryData<string>
-                {
+            new()
+            {
                     nameof(KnownQuantizers.Octree),
                     nameof(KnownQuantizers.WebSafe),
                     nameof(KnownQuantizers.Werner),
diff --git a/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs
index 824ca535bf..6bf606ac90 100644
--- a/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Gif/GifDecoderTests.cs
@@ -17,13 +17,12 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Gif
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Gif")]
     public class GifDecoderTests
     {
         private const PixelTypes TestPixelTypes = PixelTypes.Rgba32 | PixelTypes.RgbaVector | PixelTypes.Argb32;
 
-        private static GifDecoder GifDecoder => new GifDecoder();
+        private static GifDecoder GifDecoder => new();
 
         public static readonly string[] MultiFrameTestFiles =
         {
diff --git a/tests/ImageSharp.Tests/Formats/Gif/GifEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Gif/GifEncoderTests.cs
index 00d43b6ffe..cb24de81b6 100644
--- a/tests/ImageSharp.Tests/Formats/Gif/GifEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Gif/GifEncoderTests.cs
@@ -13,7 +13,6 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Gif
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Gif")]
     public class GifEncoderTests
     {
@@ -21,7 +20,7 @@ public class GifEncoderTests
         private static readonly ImageComparer ValidatorComparer = ImageComparer.TolerantPercentage(0.0015F);
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
-        new TheoryData<string, int, int, PixelResolutionUnit>
+        new()
         {
             { TestImages.Gif.Rings, (int)ImageMetadata.DefaultHorizontalResolution, (int)ImageMetadata.DefaultVerticalResolution, PixelResolutionUnit.PixelsPerInch },
             { TestImages.Gif.Ratio1x4, 1, 4, PixelResolutionUnit.AspectRatio },
diff --git a/tests/ImageSharp.Tests/Formats/Gif/GifMetadataTests.cs b/tests/ImageSharp.Tests/Formats/Gif/GifMetadataTests.cs
index 59f7ebb747..5699b47418 100644
--- a/tests/ImageSharp.Tests/Formats/Gif/GifMetadataTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Gif/GifMetadataTests.cs
@@ -12,12 +12,11 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Gif
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Gif")]
     public class GifMetadataTests
     {
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
-            new TheoryData<string, int, int, PixelResolutionUnit>
+            new()
             {
                 { TestImages.Gif.Rings, (int)ImageMetadata.DefaultHorizontalResolution, (int)ImageMetadata.DefaultVerticalResolution, PixelResolutionUnit.PixelsPerInch },
                 { TestImages.Gif.Ratio1x4, 1, 4, PixelResolutionUnit.AspectRatio },
@@ -25,7 +24,7 @@ public class GifMetadataTests
             };
 
         public static readonly TheoryData<string, uint> RepeatFiles =
-            new TheoryData<string, uint>
+            new()
             {
                 { TestImages.Gif.Cheers, 0 },
                 { TestImages.Gif.Receipt, 1 },
diff --git a/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs
index dcdfc3e421..08d8d90382 100644
--- a/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs
@@ -21,8 +21,7 @@
 namespace SixLabors.ImageSharp.Tests.Formats.Jpg
 {
     // TODO: Scatter test cases into multiple test classes
-    [Collection("RunSerial")]
-    [Trait("Format", "Jpg")]
+     [Trait("Format", "Jpg")]
     public partial class JpegDecoderTests
     {
         public const PixelTypes CommonNonDefaultPixelTypes = PixelTypes.Rgba32 | PixelTypes.Argb32 | PixelTypes.Bgr24 | PixelTypes.RgbaVector;
diff --git a/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs
index 62952f537b..18eae9fbd3 100644
--- a/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs
@@ -19,23 +19,22 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Jpg
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Jpg")]
     public class JpegEncoderTests
     {
-        private static JpegEncoder JpegEncoder => new JpegEncoder();
+        private static JpegEncoder JpegEncoder => new();
 
-        private static JpegDecoder JpegDecoder => new JpegDecoder();
+        private static JpegDecoder JpegDecoder => new();
 
         public static readonly TheoryData<string, int> QualityFiles =
-            new TheoryData<string, int>
+            new()
             {
                 { TestImages.Jpeg.Baseline.Calliphora, 80 },
                 { TestImages.Jpeg.Progressive.Fb, 75 }
             };
 
         public static readonly TheoryData<JpegColorType, int> BitsPerPixel_Quality =
-            new TheoryData<JpegColorType, int>
+            new()
             {
                 { JpegColorType.YCbCrRatio420, 40 },
                 { JpegColorType.YCbCrRatio420, 60 },
@@ -49,7 +48,7 @@ public class JpegEncoderTests
             };
 
         public static readonly TheoryData<int> Grayscale_Quality =
-            new TheoryData<int>
+            new()
             {
                 { 40 },
                 { 60 },
@@ -57,7 +56,7 @@ public class JpegEncoderTests
             };
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
-            new TheoryData<string, int, int, PixelResolutionUnit>
+            new()
             {
                 { TestImages.Jpeg.Baseline.Ratio1x1, 1, 1, PixelResolutionUnit.AspectRatio },
                 { TestImages.Jpeg.Baseline.Snake, 300, 300, PixelResolutionUnit.PixelsPerInch },
diff --git a/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs
index 9fc4d03dda..543a544d06 100644
--- a/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs
@@ -16,13 +16,12 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Png
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Png")]
     public partial class PngDecoderTests
     {
         private const PixelTypes PixelTypes = Tests.PixelTypes.Rgba32 | Tests.PixelTypes.RgbaVector | Tests.PixelTypes.Argb32;
 
-        private static PngDecoder PngDecoder => new PngDecoder();
+        private static PngDecoder PngDecoder => new();
 
         public static readonly string[] CommonTestImages =
         {
diff --git a/tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.cs
index 9e99dded88..3cc879d6b5 100644
--- a/tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Png/PngEncoderTests.cs
@@ -15,21 +15,20 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Png
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Png")]
     public partial class PngEncoderTests
     {
-        private static PngEncoder PngEncoder => new PngEncoder();
+        private static PngEncoder PngEncoder => new();
 
         public static readonly TheoryData<string, PngBitDepth> PngBitDepthFiles =
-        new TheoryData<string, PngBitDepth>
+        new()
         {
             { TestImages.Png.Rgb48Bpp, PngBitDepth.Bit16 },
             { TestImages.Png.Bpp1, PngBitDepth.Bit1 }
         };
 
         public static readonly TheoryData<string, PngBitDepth, PngColorType> PngTrnsFiles =
-        new TheoryData<string, PngBitDepth, PngColorType>
+        new()
         {
             { TestImages.Png.Gray1BitTrans, PngBitDepth.Bit1, PngColorType.Grayscale },
             { TestImages.Png.Gray2BitTrans, PngBitDepth.Bit2, PngColorType.Grayscale },
@@ -43,7 +42,7 @@ public partial class PngEncoderTests
         /// <summary>
         /// All types except Palette
         /// </summary>
-        public static readonly TheoryData<PngColorType> PngColorTypes = new TheoryData<PngColorType>
+        public static readonly TheoryData<PngColorType> PngColorTypes = new()
         {
             PngColorType.RgbWithAlpha,
             PngColorType.Rgb,
@@ -51,7 +50,7 @@ public partial class PngEncoderTests
             PngColorType.GrayscaleWithAlpha,
         };
 
-        public static readonly TheoryData<PngFilterMethod> PngFilterMethods = new TheoryData<PngFilterMethod>
+        public static readonly TheoryData<PngFilterMethod> PngFilterMethods = new()
         {
             PngFilterMethod.None,
             PngFilterMethod.Sub,
@@ -65,7 +64,7 @@ public partial class PngEncoderTests
         /// All types except Palette
         /// </summary>
         public static readonly TheoryData<PngCompressionLevel> CompressionLevels
-        = new TheoryData<PngCompressionLevel>
+        = new()
         {
             PngCompressionLevel.Level0,
             PngCompressionLevel.Level1,
@@ -79,12 +78,12 @@ public static readonly TheoryData<PngCompressionLevel> CompressionLevels
             PngCompressionLevel.Level9,
         };
 
-        public static readonly TheoryData<int> PaletteSizes = new TheoryData<int>
+        public static readonly TheoryData<int> PaletteSizes = new()
         {
             30, 55, 100, 201, 255
         };
 
-        public static readonly TheoryData<int> PaletteLargeOnly = new TheoryData<int>
+        public static readonly TheoryData<int> PaletteLargeOnly = new()
         {
             80, 100, 120, 230
         };
@@ -96,7 +95,7 @@ public static readonly TheoryData<PngCompressionLevel> CompressionLevels
         };
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
-        new TheoryData<string, int, int, PixelResolutionUnit>
+        new()
         {
             { TestImages.Png.Splash, 11810, 11810, PixelResolutionUnit.PixelsPerMeter },
             { TestImages.Png.Ratio1x4, 1, 4, PixelResolutionUnit.AspectRatio },
diff --git a/tests/ImageSharp.Tests/Formats/Tga/TgaDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Tga/TgaDecoderTests.cs
index bd7a6e07a0..55dc2ecdd8 100644
--- a/tests/ImageSharp.Tests/Formats/Tga/TgaDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Tga/TgaDecoderTests.cs
@@ -15,11 +15,10 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Tga
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Tga")]
     public class TgaDecoderTests
     {
-        private static TgaDecoder TgaDecoder => new TgaDecoder();
+        private static TgaDecoder TgaDecoder => new();
 
         [Theory]
         [WithFile(Gray8BitTopLeft, PixelTypes.Rgba32)]
diff --git a/tests/ImageSharp.Tests/Formats/Tga/TgaEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Tga/TgaEncoderTests.cs
index da8ff8018e..0683f90fd6 100644
--- a/tests/ImageSharp.Tests/Formats/Tga/TgaEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Tga/TgaEncoderTests.cs
@@ -11,19 +11,18 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Tga
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Tga")]
     public class TgaEncoderTests
     {
         public static readonly TheoryData<TgaBitsPerPixel> BitsPerPixel =
-            new TheoryData<TgaBitsPerPixel>
+            new()
             {
                 TgaBitsPerPixel.Pixel24,
                 TgaBitsPerPixel.Pixel32
             };
 
         public static readonly TheoryData<string, TgaBitsPerPixel> TgaBitsPerPixelFiles =
-            new TheoryData<string, TgaBitsPerPixel>
+            new()
             {
                 { Gray8BitBottomLeft, TgaBitsPerPixel.Pixel8 },
                 { Bit16BottomLeft, TgaBitsPerPixel.Pixel16 },
diff --git a/tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs
index 4a13bbe626..b7bd5275d5 100644
--- a/tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs
@@ -15,15 +15,14 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Tiff")]
     public class TiffDecoderTests
     {
         public static readonly string[] MultiframeTestImages = Multiframes;
 
-        private static TiffDecoder TiffDecoder => new TiffDecoder();
+        private static TiffDecoder TiffDecoder => new();
 
-        private static MagickReferenceDecoder ReferenceDecoder => new MagickReferenceDecoder();
+        private static MagickReferenceDecoder ReferenceDecoder => new();
 
         [Theory]
         [WithFile(RgbUncompressedTiled, PixelTypes.Rgba32)]
diff --git a/tests/ImageSharp.Tests/Formats/Tiff/TiffEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Tiff/TiffEncoderTests.cs
index d85ed16a71..aded52cd9b 100644
--- a/tests/ImageSharp.Tests/Formats/Tiff/TiffEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Tiff/TiffEncoderTests.cs
@@ -11,7 +11,6 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Tiff")]
     public class TiffEncoderTests : TiffEncoderBaseTester
     {
diff --git a/tests/ImageSharp.Tests/Formats/Tiff/TiffMetadataTests.cs b/tests/ImageSharp.Tests/Formats/Tiff/TiffMetadataTests.cs
index c912ae26bd..7715ac3a38 100644
--- a/tests/ImageSharp.Tests/Formats/Tiff/TiffMetadataTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Tiff/TiffMetadataTests.cs
@@ -17,11 +17,10 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Tiff")]
     public class TiffMetadataTests
     {
-        private static TiffDecoder TiffDecoder => new TiffDecoder();
+        private static TiffDecoder TiffDecoder => new();
 
         private class NumberComparer : IEqualityComparer<Number>
         {
diff --git a/tests/ImageSharp.Tests/Formats/WebP/WebpDecoderTests.cs b/tests/ImageSharp.Tests/Formats/WebP/WebpDecoderTests.cs
index 2cbeff2ceb..22342e612f 100644
--- a/tests/ImageSharp.Tests/Formats/WebP/WebpDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/WebP/WebpDecoderTests.cs
@@ -12,7 +12,6 @@
 // ReSharper disable InconsistentNaming
 namespace SixLabors.ImageSharp.Tests.Formats.Webp
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Webp")]
     public class WebpDecoderTests
     {
diff --git a/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs b/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs
index ec0040a465..607d4c7646 100644
--- a/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs
@@ -11,7 +11,6 @@
 
 namespace SixLabors.ImageSharp.Tests.Formats.Webp
 {
-    [Collection("RunSerial")]
     [Trait("Format", "Webp")]
     public class WebpEncoderTests
     {
diff --git a/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs b/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs
index 80c8cc6a06..c4bb03d020 100644
--- a/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs
+++ b/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs
@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -310,6 +310,7 @@ private static void AllocateGroupAndForget(UniformUnmanagedMemoryPoolMemoryAlloc
             }
         }
 
+        [ActiveIssue("https://github.com/SixLabors/ImageSharp/issues/1887", TestPlatforms.OSX)]
         [Theory]
         [InlineData(300)] // Group of single SharedArrayPoolBuffer<T>
         [InlineData(600)] // Group of single UniformUnmanagedMemoryPool buffer