OpenTelemetry

This feature requires the Microsoft.Testing.Extensions.OpenTelemetry NuGet package.

This extension integrates OpenTelemetry with Microsoft.Testing.Platform (MTP), allowing test runs to emit traces and metrics through the standard OpenTelemetry SDK.

Note

This extension is available in MTP starting with version 2.1.0.

Important

Starting with MTP 2.4.0, the OpenTelemetry extension follows the MTP release version and its public entry points are no longer experimental.

Registration

Note

This extension doesn't support auto-registration. You must register it manually by disabling the auto-generated entry point (<GenerateTestingPlatformEntryPoint>false</GenerateTestingPlatformEntryPoint>) and calling AddOpenTelemetryProvider in your Main method.

var builder = await TestApplication.CreateBuilderAsync(args);

builder.AddOpenTelemetryProvider(
    withTracing: tracing => tracing
        .AddTestingPlatformInstrumentation()
        .AddConsoleExporter(),
    withMetrics: metrics => metrics
        .AddTestingPlatformInstrumentation()
        .AddConsoleExporter()
);

using var app = await builder.BuildAsync();
return await app.RunAsync();

To configure instrumentation, resource attributes, and an OTLP exporter from standard OTEL_* environment variables, call:

builder.AddOpenTelemetryProviderFromEnvironment();

The method adds instrumentation only when you configure an exporter or pass a configuration callback, so you can leave the registration in the application when some environments don't export telemetry.

API

AddOpenTelemetryProvider

Registers the OpenTelemetry provider on ITestApplicationBuilder. Accepts two optional callbacks:

• withTracing: configures the TracerProviderBuilder for distributed tracing.
• withMetrics: configures the MeterProviderBuilder for metrics collection.

AddTestingPlatformInstrumentation

Call on TracerProviderBuilder or MeterProviderBuilder to subscribe to the built-in Microsoft.Testing.Platform activity source and meter.

AddTestingPlatformResource

Call on ResourceBuilder to add test assembly, host, operating system, and runtime attributes. The detector also identifies CI provider, pipeline, branch, and commit information for GitHub Actions, Azure Pipelines, GitLab CI, and Jenkins.

AddOpenTelemetryProviderFromEnvironment

Registers tracing, metrics, resource detection, and an OTLP exporter from standard OpenTelemetry environment variables. OTEL_SDK_DISABLED=true disables the integration. Configure OTEL_TRACES_EXPORTER, OTEL_METRICS_EXPORTER, or OTEL_EXPORTER_OTLP_ENDPOINT to activate export.

Activity source and meter

The extension emits telemetry under:

• Activity source: Microsoft.Testing.Platform
• Meter: Microsoft.Testing.Platform

Semantic conventions

MTP emits standard OpenTelemetry testing and code attributes where a convention exists, including test.case.name, test.case.result.status, test.suite.name, code.function.name, code.file.path, code.line.number, code.stacktrace, and error.type. Failed tests set the span status to Error and add an exception event.

MTP extends the conventions with additional result states (skipped, error, timeout, cancelled, and unknown) and test attributes for concepts that OpenTelemetry doesn't define. To preserve existing dashboards, legacy attribute and instrument names remain enabled by default.

When the launching process supplies TRACEPARENT and TRACESTATE, MTP places the test run under that trace instead of starting an unrelated root trace.

Emitted metrics

Instrument	Type	Unit	Description
test.case.duration	Histogram	s	Test duration, grouped by result status and suite.
test.case.result.count	Counter	{test}	Completed tests, grouped by result status and suite.
test.case.active	UpDownCounter	{test}	Tests that are currently running.
test.run.duration	Histogram	s	Run duration, grouped by result status and exit code.
test.case.retry.count	Counter	{test}	Tests scheduled for another attempt by the retry extension.

Environment configuration

Environment variable	Default	Description
TRACEPARENT, TRACESTATE	Unset	W3C trace context for the parent run.
TESTINGPLATFORM_OTEL_CAPTURE_TEST_OUTPUT	1	Attaches captured standard output and error to test spans. Set to 0 when output might contain secrets.
TESTINGPLATFORM_OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT	8192	Sets the maximum characters retained for a string attribute.
TESTINGPLATFORM_OTEL_EMIT_LEGACY_ATTRIBUTES	1	Emits legacy attribute and instrument names alongside semantic-convention names.
OTEL_SDK_DISABLED	Unset	Set to true to disable the OpenTelemetry SDK.
OTEL_SERVICE_NAME	Unset	Overrides the service name.
OTEL_EXPORTER_OTLP_ENDPOINT	Unset	Sets the OTLP endpoint.
OTEL_TRACES_EXPORTER, OTEL_METRICS_EXPORTER	Unset	Selects trace and metric exporters.