testing

ExampleNewTestMeterProvider demonstrates how to use the test meter provider to assert metrics created by your code.

package main

import (
	"context"
	"fmt"

	"go.opentelemetry.io/otel"

	obtest "github.com/gaborage/go-bricks/observability/testing"
)

func main() {
	// Create a test meter provider with manual reader
	mp := obtest.NewTestMeterProvider()
	defer mp.Shutdown(context.Background())

	// Set as global provider (or use directly)
	otel.SetMeterProvider(mp)

	// Your code that records metrics
	meter := mp.Meter("example-service")
	counter, _ := meter.Int64Counter("requests.count") // Metric options can be added here

	counter.Add(context.Background(), 1) // Attributes can be added to metric recordings

	counter.Add(context.Background(), 2)

	// Collect metrics for assertions
	// In real usage, you would pass the testing.T instance
	// rm := mp.Collect(t)
	fmt.Println("Metrics collected successfully")
}

Output:

Metrics collected successfully

ExampleNewTestTraceProvider demonstrates how to use the test trace provider to assert spans created by your code.

package main

import (
	"context"
	"fmt"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"

	obtest "github.com/gaborage/go-bricks/observability/testing"
)

const httpMethodAttr = "http.method"

func main() {
	// Create a test trace provider with in-memory exporter
	tp := obtest.NewTestTraceProvider()
	defer tp.Shutdown(context.Background())

	// Set as global provider (or use directly)
	otel.SetTracerProvider(tp)

	// Your code that creates spans
	tracer := tp.Tracer("example-service")
	_, span := tracer.Start(context.Background(), "process-request")
	span.SetAttributes(
		attribute.String(httpMethodAttr, "GET"),
		attribute.String("http.url", "/api/users"),
		attribute.Int("http.status_code", 200),
	)
	span.End()

	// Get captured spans for assertions
	spans := tp.Exporter.GetSpans()
	fmt.Printf("Captured %d spans\n", len(spans))
}

Output:

Captured 1 spans