[Logs] UnitTest: LogRecord attribute limits (#3758)

* Unittest for LogRecord attribute limits

* Remove maxValueLength from LogRecordExtensions.AddIntAttribute.

Change requested from #3684 (comment)

* Pr commits addressed

Co-authored-by: Mikel Blanchard <[email protected]>

Author: Jonathan Wilhelm

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/LogRecordExtensions.cs

@@ -92,7 +92,7 @@ internal static OtlpLogs.LogRecord ToOtlpLog(this LogRecord logRecord, SdkLimitO
 
                 if (logRecord.EventId.Id != default)
                 {
-                    otlpLogRecord.AddIntAttribute(nameof(logRecord.EventId.Id), logRecord.EventId.Id, attributeValueLengthLimit, attributeCountLimit);
+                    otlpLogRecord.AddIntAttribute(nameof(logRecord.EventId.Id), logRecord.EventId.Id, attributeCountLimit);
                 }
 
                 if (!string.IsNullOrEmpty(logRecord.EventId.Name))
@@ -193,10 +193,10 @@ private static void AddStringAttribute(this OtlpLogs.LogRecord logRecord, string
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static void AddIntAttribute(this OtlpLogs.LogRecord logRecord, string key, int value, int? maxValueLength, int maxAttributeCount)
+        private static void AddIntAttribute(this OtlpLogs.LogRecord logRecord, string key, int value, int maxAttributeCount)
         {
             var attributeItem = new KeyValuePair<string, object>(key, value);
-            if (OtlpKeyValueTransformer.Instance.TryTransformTag(attributeItem, out var result, maxValueLength))
+            if (OtlpKeyValueTransformer.Instance.TryTransformTag(attributeItem, out var result))
             {
                 logRecord.AddAttribute(result, maxAttributeCount);
             }

test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/OtlpLogExporterTests.cs

@@ -17,6 +17,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
@@ -26,6 +27,7 @@
 using OpenTelemetry.Tests;
 using OpenTelemetry.Trace;
 using Xunit;
+using OtlpCommon = OpenTelemetry.Proto.Common.V1;
 using OtlpLogs = OpenTelemetry.Proto.Logs.V1;
 
 namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests
@@ -458,5 +460,52 @@ public void CheckToOtlpLogRecordExceptionAttributes()
             Assert.Contains(SemanticConventions.AttributeExceptionStacktrace, otlpLogRecordAttributes);
             Assert.Contains(logRecord.Exception.ToInvariantString(), otlpLogRecordAttributes);
         }
+
+        [Fact]
+        public void CheckToOtlpLogRecordRespectsAttributeLimits()
+        {
+            var sdkLimitOptions = new SdkLimitOptions
+            {
+                AttributeCountLimit = 3, // 3 => LogCategory, exception.type and exception.message
+                AttributeValueLengthLimit = 8,
+            };
+
+            var logRecords = new List<LogRecord>();
+            using var loggerFactory = LoggerFactory.Create(builder =>
+            {
+                builder.AddOpenTelemetry(options =>
+                {
+                    options.AddInMemoryExporter(logRecords);
+                });
+            });
+
+            var logger = loggerFactory.CreateLogger("OtlpLogExporterTests");
+            logger.LogInformation(new NotSupportedException("I'm the exception message."), "Exception Occurred");
+
+            var logRecord = logRecords[0];
+            var otlpLogRecord = logRecord.ToOtlpLog(sdkLimitOptions);
+
+            Assert.NotNull(otlpLogRecord);
+            Assert.Equal(1u, otlpLogRecord.DroppedAttributesCount);
+
+            var exceptionTypeAtt = TryGetAttribute(otlpLogRecord, SemanticConventions.AttributeExceptionType);
+            Assert.NotNull(exceptionTypeAtt);
+
+            // "NotSuppo" == first 8 chars from the exception typename "NotSupportedException"
+            Assert.Equal("NotSuppo", exceptionTypeAtt.Value.StringValue);
+            var exceptionMessageAtt = TryGetAttribute(otlpLogRecord, SemanticConventions.AttributeExceptionMessage);
+            Assert.NotNull(exceptionMessageAtt);
+
+            // "I'm the " == first 8 chars from the exception message
+            Assert.Equal("I'm the ", exceptionMessageAtt.Value.StringValue);
+
+            var exceptionStackTraceAtt = TryGetAttribute(otlpLogRecord, SemanticConventions.AttributeExceptionStacktrace);
+            Assert.Null(exceptionStackTraceAtt);
+        }
+
+        private static OtlpCommon.KeyValue TryGetAttribute(OtlpLogs.LogRecord record, string key)
+        {
+            return record.Attributes.FirstOrDefault(att => att.Key == key);
+        }
     }
 }