fix: libmonosgen and libxamarin frames currently showing as inapp

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Fixes
 
 - The SDK now logs a `Warning` instead of an `Error` when being ratelimited ([#4927](https://github.com/getsentry/sentry-dotnet/pull/4927))
+- libmonosgen and libxamarin frames no longer show as inapp ([#4960](https://github.com/getsentry/sentry-dotnet/pull/4960))
 
 ## 6.2.0-alpha.0
 

src/Sentry/SentryOptions.cs

@@ -1904,6 +1904,14 @@ internal static List<StringOrRegex> GetDefaultInAppExclude() =>
         "Grpc",
         "ServiceStack",
         "Java.Interop",
+        // (^|[/\\]) — anchors to start of string or after a forward/backward slash
+        // ([^/\\]*libmonosgen[^/\\]*) — last segment contains libxamarin (no slashes before/after)
+        // $ — end of string
+        new Regex(@"(^|[/\\])([^/\\]*libmonosgen[^/\\]*)$"),
+        // (^|[/\\]) — anchors to start of string or after a forward/backward slash
+        // ([^/\\]*libxamarin[^/\\]*) — last segment contains libxamarin (no slashes before/after)
+        // $ — end of string
+        new Regex(@"(^|[/\\])([^/\\]*libxamarin[^/\\]*)$")
     ];
 
     /// <summary>

test/Sentry.Tests/Protocol/Exceptions/SentryStackFrameTests.cs

@@ -239,6 +239,46 @@ public void ConfigureAppFrame_WithDefaultOptions_NotBuiltInIgnoredMarkedAsInApp(
         Assert.True(sut.InApp);
     }
 
+    [Theory]
+    [InlineData("foolibmonosgenbar", false)]
+    [InlineData("/data/Containers/Bundle/Application/Example.app/libmonosgen-dotnet-release.dylib", false)]
+    [InlineData("/data/libmonosgen/something-else.dylib ", true)]
+    public void ConfigureAppFrame_WithDefaultOptions_ExcludesMonoFrames(string package, bool expectedInApp)
+    {
+        var options = new SentryOptions();
+        var sut = new SentryStackFrame
+        {
+            Function = "async void MainActivity.OnCreate(Bundle savedInstanceState)+(?) =\\u003E { }",
+            Package = package
+        };
+
+        // Act
+        sut.ConfigureAppFrame(options);
+
+        // Assert
+        Assert.Equal(sut.InApp, expectedInApp);
+    }
+
+    [Theory]
+    [InlineData("foolibxamarinbar", false)]
+    [InlineData("/data/Containers/Bundle/Application/Example.app/libxamarin-dotnet-release.dylib", false)]
+    [InlineData("/data/libxamarin/something-else.dylib ", true)]
+    public void ConfigureAppFrame_WithDefaultOptions_ExcludesXamarinFrames(string package, bool expectedInApp)
+    {
+        var options = new SentryOptions();
+        var sut = new SentryStackFrame
+        {
+            Function = "async void MainActivity.OnCreate(Bundle savedInstanceState)+(?) =\\u003E { }",
+            Package = package
+        };
+
+        // Act
+        sut.ConfigureAppFrame(options);
+
+        // Assert
+        Assert.Equal(sut.InApp, expectedInApp);
+    }
+
     [Fact]
     public void ConfigureAppFrame_WithDefaultOptions_JavaPackageNotInApp()
     {