[OTLP] Add property-based fuzz testing for ProtobufOtlp serializers

Directory.Packages.props

@@ -91,6 +91,7 @@
   <ItemGroup>
     <PackageVersion Include="BenchmarkDotNet" Version="0.15.8" />
     <PackageVersion Include="CommandLineParser" Version="2.9.1" />
+    <PackageVersion Include="FsCheck.Xunit" Version="3.3.2" />
     <PackageVersion Include="GitHubActionsTestLogger" Version="3.0.1" />
     <PackageVersion Include="Grpc.AspNetCore" Version="2.67.0" />
     <PackageVersion Include="Grpc.AspNetCore.Server" Version="2.67.0" />

OpenTelemetry.slnx

@@ -221,6 +221,7 @@
   <Project Path="test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/OpenTelemetry.Api.ProviderBuilderExtensions.Tests.csproj" />
   <Project Path="test/OpenTelemetry.Api.Tests/OpenTelemetry.Api.Tests.csproj" />
   <Project Path="test/OpenTelemetry.Exporter.Console.Tests/OpenTelemetry.Exporter.Console.Tests.csproj" />
+  <Project Path="test/OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests/OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests.csproj" />
   <Project Path="test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests.csproj" />
   <Project Path="test/OpenTelemetry.Exporter.Prometheus.AspNetCore.Tests/OpenTelemetry.Exporter.Prometheus.AspNetCore.Tests.csproj" />
   <Project Path="test/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests.csproj" />

build/Common.nonprod.props

@@ -11,7 +11,7 @@
     <DefaultTargetFrameworkForExampleApps>net10.0</DefaultTargetFrameworkForExampleApps>
   </PropertyGroup>
 
-  <PropertyGroup Condition="$(MSBuildProjectName.EndsWith('.Tests'))">
+  <PropertyGroup Condition="$(MSBuildProjectName.EndsWith('.Tests')) OR $(MSBuildProjectName.EndsWith('.FuzzTests'))">
     <IsTestProject>true</IsTestProject>
   </PropertyGroup>
 

src/OpenTelemetry.Api/OpenTelemetry.Api.csproj

@@ -30,6 +30,7 @@
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.Console" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.InMemory" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" PublicKey="$(StrongNamePublicKey)" />
+    <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Extensions.Hosting" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Extensions.Hosting.Tests" PublicKey="$(StrongNamePublicKey)" />

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OpenTelemetry.Exporter.OpenTelemetryProtocol.csproj

@@ -43,6 +43,7 @@
   <ItemGroup>
     <InternalsVisibleTo Include="Benchmarks" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="MockOpenTelemetryCollector" PublicKey="$(StrongNamePublicKey)" />
+    <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests" PublicKey="$(StrongNamePublicKey)" />
   </ItemGroup>
 

src/OpenTelemetry/OpenTelemetry.csproj

@@ -31,6 +31,7 @@
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.Console" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.InMemory" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" PublicKey="$(StrongNamePublicKey)" />
+    <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.Prometheus.AspNetCore" PublicKey="$(StrongNamePublicKey)" />
     <InternalsVisibleTo Include="OpenTelemetry.Exporter.Prometheus.AspNetCore.Tests" PublicKey="$(StrongNamePublicKey)" />

test/OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests/Generators.cs

@@ -0,0 +1,236 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Diagnostics;
+using System.Diagnostics.Metrics;
+using FsCheck;
+using FsCheck.Fluent;
+using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation;
+using OpenTelemetry.Logs;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
+
+namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests;
+
+internal static class Generators
+{
+    public static readonly ActivitySource TestActivitySource = new("Fuzz.ActivitySource", "1.0.0");
+
+    private static readonly Gen<ActivityStatusCode> ActivityStatusCodes = Gen.Elements(
+    [
+        ActivityStatusCode.Unset,
+        ActivityStatusCode.Ok,
+        ActivityStatusCode.Error,
+    ]);
+
+    private static readonly Gen<LogRecordSeverity> LogRecordSeverities = Gen.Elements(
+    [
+        LogRecordSeverity.Debug,
+        LogRecordSeverity.Error,
+        LogRecordSeverity.Fatal,
+        LogRecordSeverity.Info,
+        LogRecordSeverity.Trace,
+        LogRecordSeverity.Unspecified,
+        LogRecordSeverity.Warn,
+    ]);
+
+    public static Arbitrary<SdkLimitOptions> SdkLimitOptionsArbitrary()
+    {
+        var gen = from spanAttributesLimit in Gen.Choose(0, 1000).Select(x => (int?)x)
+                  from spanEventsLimit in Gen.Choose(0, 1000).Select(x => (int?)x)
+                  from spanLinksLimit in Gen.Choose(0, 1000).Select(x => (int?)x)
+                  from spanEventAttributesLimit in Gen.Choose(0, 1000).Select(x => (int?)x)
+                  from spanLinkAttributesLimit in Gen.Choose(0, 1000).Select(x => (int?)x)
+                  from attributeValueLimit in Gen.Choose(0, 10000).Select(x => (int?)x)
+                  from logAttributesLimit in Gen.Choose(0, 1000).Select(x => (int?)x)
+                  select new SdkLimitOptions
+                  {
+                      AttributeValueLengthLimit = attributeValueLimit,
+                      LogRecordAttributeCountLimit = logAttributesLimit,
+                      SpanAttributeCountLimit = spanAttributesLimit,
+                      SpanEventAttributeCountLimit = spanEventAttributesLimit,
+                      SpanEventCountLimit = spanEventsLimit,
+                      SpanLinkAttributeCountLimit = spanLinkAttributesLimit,
+                      SpanLinkCountLimit = spanLinksLimit,
+                  };
+
+        return gen.ToArbitrary();
+    }
+
+    public static Arbitrary<Activity> ActivityArbitrary(ActivityStatusCode? status = default)
+    {
+        var gen = Gen.Sized(size =>
+        {
+            var activity = TestActivitySource.StartActivity($"TestActivity_{Guid.NewGuid():N}");
+            if (activity == null)
+            {
+                return Gen.Constant(new Activity("Fallback"));
+            }
+
+            // Generate tags
+            var tagCount = Math.Min(size, 50);
+            for (int i = 0; i < tagCount; i++)
+            {
+                activity.SetTag($"tag.{i}", $"value_{i}_{Guid.NewGuid():N}");
+            }
+
+            // Generate events
+            var eventCount = Math.Min(size / 10, 10);
+            for (int i = 0; i < eventCount; i++)
+            {
+                var eventTags = new ActivityTagsCollection
+                {
+                    { $"event.tag.{i}", $"event_value_{i}" },
+                };
+                activity.AddEvent(new ActivityEvent($"Event_{i}", DateTimeOffset.UtcNow, eventTags));
+            }
+
+            // Generate links
+            var linkCount = Math.Min(size / 10, 10);
+            for (int i = 0; i < linkCount; i++)
+            {
+                var linkTags = new ActivityTagsCollection
+                {
+                    { $"link.tag.{i}", $"link_value_{i}" },
+                };
+
+                var context = new ActivityContext(
+                    ActivityTraceId.CreateRandom(),
+                    ActivitySpanId.CreateRandom(),
+                    ActivityTraceFlags.Recorded);
+
+                activity.AddLink(new ActivityLink(context, linkTags));
+            }
+
+            activity.SetStatus(status ?? ActivityStatusCodes.Sample(size, 1).First());
+
+            return Gen.Constant(activity);
+        });
+
+        return gen.ToArbitrary();
+    }
+
+    public static Arbitrary<Resource> ResourceArbitrary()
+    {
+        var gen = Gen.Sized(size =>
+        {
+            var count = Math.Min(size, 20);
+            var attributes = new Dictionary<string, object>(count);
+
+            for (int i = 0; i < count; i++)
+            {
+                attributes[$"resource.attr.{i}"] = $"value_{i}";
+            }
+
+            return Gen.Constant(Resource.Empty.Merge(new Resource(attributes)));
+        });
+
+        return gen.ToArbitrary();
+    }
+
+    /// <summary>
+    /// Generates valid Metric instances for different metric types.
+    /// </summary>
+    public static Arbitrary<Batch<Metric>> BatchMetricArbitrary()
+    {
+        var gen = Gen.Sized(size =>
+        {
+            var metrics = new List<Metric>();
+
+            var builder = Sdk.CreateMeterProviderBuilder()
+                .AddMeter("FuzzTest.Meter")
+                .AddInMemoryExporter(metrics);
+
+            if (size % 7 == 0)
+            {
+                var boundaries = new double[Math.Min(size % 10, 10)];
+                for (int i = 0; i < boundaries.Length; i++)
+                {
+                    boundaries[i] = (i * 50.0) + (size % 50);
+                }
+
+                builder.AddView("test.histogram", new ExplicitBucketHistogramConfiguration { Boundaries = boundaries });
+            }
+
+            using (var meterProvider = builder.Build())
+            {
+                using var meter = new Meter("FuzzTest.Meter", "1.0.0");
+
+                var counter = meter.CreateCounter<long>("test.counter");
+
+                for (int i = 0; i < size; i++)
+                {
+                    counter.Add(100 * i);
+                }
+
+                var gauge = meter.CreateGauge<double>("test.gauge");
+
+                for (int i = 0; i < size; i++)
+                {
+                    gauge.Record(0.1 * i);
+                }
+
+                var histogram = meter.CreateHistogram<int>("test.histogram");
+
+                for (int i = 0; i < size; i++)
+                {
+                    histogram.Record(300 * i);
+                }
+
+                meterProvider.ForceFlush();
+            }
+
+            var batch = new Batch<Metric>([.. metrics], metrics.Count);
+
+            return Gen.Constant(batch);
+        });
+
+        return gen.ToArbitrary();
+    }
+
+    /// <summary>
+    /// Generates valid LogRecord instances.
+    /// </summary>
+    public static Arbitrary<LogRecord> LogRecordArbitrary(LogRecordSeverity? severity = default)
+    {
+        var gen = Gen.Sized(size =>
+        {
+            var logRecord = LogRecordSharedPool.Current.Rent();
+
+            logRecord.Severity = severity ?? LogRecordSeverities.Sample(size, 1).First();
+            logRecord.Timestamp = DateTime.UtcNow;
+
+            // Add attributes
+            var count = Math.Min(size, 50);
+            var attributes = new List<KeyValuePair<string, object?>>(count);
+            for (int i = 0; i < count; i++)
+            {
+                attributes.Add(new KeyValuePair<string, object?>($"log.attribute.{i}", $"value_{i}"));
+            }
+
+            if (attributes.Count > 0)
+            {
+                logRecord.Attributes = attributes;
+            }
+
+            return Gen.Constant(logRecord);
+        });
+
+        return gen.ToArbitrary();
+    }
+
+    public static Arbitrary<Activity[]> ActivityBatchArbitrary()
+    {
+        var gen = Gen.Sized(size =>
+        {
+            var batchSize = Math.Min(size, 100);
+            return Gen.ArrayOf(ActivityArbitrary().Generator, batchSize);
+        });
+
+        return gen.ToArbitrary();
+    }
+
+    public static Arbitrary<int> BufferSizeArbitrary() => Gen.Choose(64, 10 * 1024 * 1024).ToArbitrary();
+
+    public static Arbitrary<LogRecordSeverity> LogRecordSeverityArbitrary() => LogRecordSeverities.ToArbitrary();
+}

test/OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests/OpenTelemetry.Exporter.OpenTelemetryProtocol.FuzzTests.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>$(TargetFrameworksForTests)</TargetFrameworks>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="FsCheck.Xunit" />
+    <PackageReference Include="Grpc" />
+    <PackageReference Include="Grpc.AspNetCore.Server" Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'" />
+    <PackageReference Include="Grpc.Net.Client" />
+    <PackageReference Include="Google.Protobuf" />
+    <PackageReference Include="Grpc.Tools" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.InMemory\OpenTelemetry.Exporter.InMemory.csproj" />
+    <ProjectReference Include="$(RepoRoot)\src\OpenTelemetry.Exporter.OpenTelemetryProtocol\OpenTelemetry.Exporter.OpenTelemetryProtocol.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Protobuf Include="$(RepoRoot)\src\Shared\Proto\**\*.proto" Link="Proto\%(RecursiveDir)%(Filename)%(Extension)" Access="internal">
+      <ProtoRoot>$(RepoRoot)\src\Shared\Proto</ProtoRoot>
+    </Protobuf>
+  </ItemGroup>
+
+</Project>