Add MacOS test pipeline and fix failing tests

.github/workflows/build_and_test_macos.yml

@@ -0,0 +1,28 @@
+name: Build and test [MacOS]
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@master
+
+      - name: Set up dotnet core
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: | 
+            2.1.x
+            6.0.x
+            8.0.x
+
+      # Build the release build
+      - name: Build the solution
+        run: dotnet build -c Release src/UglyToad.PdfPig.sln
+
+      - name: Run the tests
+        run: dotnet test -c Release src/UglyToad.PdfPig.sln

src/UglyToad.PdfPig.Tests/Integration/LetterFilterTests.cs

@@ -1,14 +1,22 @@
 namespace UglyToad.PdfPig.Tests.Integration
 {
+    using PdfPig.Fonts.SystemFonts;
     using System.Linq;
 
     public class LetterFilterTests
     {
-        [Fact]
+        [SkippableFact]
         public void CanFilterClippedLetters()
         {
             var one = IntegrationHelpers.GetDocumentPath("ClipPathLetterFilter-Test1.pdf");
 
+            // The 'TimesNewRomanPSMT' font is used by this particular document. Thus, results cannot be trusted on
+            // platforms where this font isn't generally available (e.g. OSX, Linux, etc.), so we skip it!
+            var font = SystemFontFinder.Instance.GetTrueTypeFont("TimesNewRomanPSMT");
+            var font1 = SystemFontFinder.Instance.GetTrueTypeFont("TimesNewRomanPS-BoldMT");
+            var font2 = SystemFontFinder.Instance.GetTrueTypeFont("TimesNewRomanPS-ItalicMT");
+            Skip.If(font is null || font1 is null || font2 is null, "Skipped because the font TimesNewRomanPSMT or a font from TimesNewRoman family could not be found in the execution environment.");
+
             using (var doc1 = PdfDocument.Open(one, new ParsingOptions { ClipPaths = true }))
             using (var doc2 = PdfDocument.Open(one, new ParsingOptions { ClipPaths = false }))
             {

src/UglyToad.PdfPig.Tests/Writer/PdfDocumentBuilderTests.cs

@@ -1252,18 +1252,18 @@ public void CanCreateDocumentWithOutline()
                     bookmarks.GetNodes().OfType<UriBookmarkNode>().Select(node => node.Uri));
 
                 Assert.Equal(
-                    new[] 
+                    new byte[] 
                     {
-                        ExplicitDestinationType.XyzCoordinates,
-                        ExplicitDestinationType.FitPage,
-                        ExplicitDestinationType.FitRectangle,
-                        ExplicitDestinationType.FitBoundingBox,
-                        ExplicitDestinationType.FitBoundingBoxHorizontally,
-                        ExplicitDestinationType.FitBoundingBoxVertically,
-                        ExplicitDestinationType.FitHorizontally,
-                        ExplicitDestinationType.FitVertically,
+                        (byte)ExplicitDestinationType.XyzCoordinates,
+                        (byte)ExplicitDestinationType.FitPage,
+                        (byte)ExplicitDestinationType.FitRectangle,
+                        (byte)ExplicitDestinationType.FitBoundingBox,
+                        (byte)ExplicitDestinationType.FitBoundingBoxHorizontally,
+                        (byte)ExplicitDestinationType.FitBoundingBoxVertically,
+                        (byte)ExplicitDestinationType.FitHorizontally,
+                        (byte)ExplicitDestinationType.FitVertically,
                     },
-                    bookmarks.GetNodes().OfType<DocumentBookmarkNode>().Select(node => node.Destination.Type));
+                    bookmarks.GetNodes().OfType<DocumentBookmarkNode>().Select(node => (byte)node.Destination.Type));
             }
         }
 

src/UglyToad.PdfPig/Encryption/AesEncryptionHelper.cs

@@ -1,13 +1,13 @@
 namespace UglyToad.PdfPig.Encryption
 {
     using System;
-    using System.IO;
     using System.Security.Cryptography;
 
     internal static class AesEncryptionHelper
     {
         public static byte[] Encrypt256()
         {
+            // See https://stackoverflow.com/questions/73779169/cryptographicexception-bad-pkcs7-padding-invalid-length-0-cannot-decrypt-sa
             throw new NotImplementedException();
         }
 
@@ -27,35 +27,28 @@ public static byte[] Decrypt(byte[] data, byte[] finalKey)
                 aes.IV = iv;
 
 #if NET8_0_OR_GREATER
-                var encryptedData = data.AsSpan(iv.Length);
-                if (encryptedData.IsEmpty)
+                if (data.Length <= iv.Length)
                 {
+                    aes.Clear();
                     return [];
                 }
-                return aes.DecryptCbc(encryptedData, iv, PaddingMode.PKCS7);
+
+                var encryptedData = data.AsSpan(iv.Length);
+                var output = aes.DecryptCbc(encryptedData, iv, PaddingMode.PKCS7);
+                aes.Clear();
+                return output;
 #else
-                var buffer = new byte[256];
+                if (data.Length <= iv.Length)
+                {
+                    aes.Clear();
+                    return [];
+                }
 
                 using (var decryptor = aes.CreateDecryptor(aes.Key, aes.IV))
-                using (var input = new MemoryStream(data))
-                using (var output = new MemoryStream())
                 {
-                    input.Seek(iv.Length, SeekOrigin.Begin);
-                    using (var cryptoStream = new CryptoStream(input, decryptor, CryptoStreamMode.Read))
-                    {
-                        int read;
-                        do
-                        {
-                            read = cryptoStream.Read(buffer, 0, buffer.Length);
-
-                            if (read > 0)
-                            {
-                                output.Write(buffer, 0, read);
-                            }
-                        } while (read > 0);
-
-                        return output.ToArray();
-                    }
+                    var output = decryptor.TransformFinalBlock(data, iv.Length, data.Length - iv.Length);
+                    aes.Clear();
+                    return output;
                 }
 #endif
             }

src/UglyToad.PdfPig/Outline/Destinations/ExplicitDestinationType.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// The display type for opening an <see cref="ExplicitDestination"/>.
     /// </summary>
-    public enum ExplicitDestinationType
+    public enum ExplicitDestinationType : byte
     {
         /// <summary>
         /// Display the page with the given top left coordinates and