docs: use test example to document prometheus.InstallNewPipeline

CHANGELOG.md

@@ -68,6 +68,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
   It no longer is a conglomerate of itself, events, and link attributes that have been dropped. (#1771)
 - Make `ExportSpans` in Jaeger Exporter honor context deadline. (#1773)
 - The `go.opentelemetry.io/otel/sdk/export/trace` package is merged into the `go.opentelemetry.io/otel/sdk/trace` package. (#1778)
+- The prometheus.InstallNewPipeline example is moved from comment to example test (#1796)
 
 ### Removed
 

exporters/metric/prometheus/example_test.go

@@ -95,3 +95,21 @@ func ExampleNewExportPipeline() {
 	// a_valuerecorder_sum{R="V",key="value"} 100
 	// a_valuerecorder_count{R="V",key="value"} 1
 }
+
+func ExampleInstallNewPipeline() {
+	exporter, err := prometheus.InstallNewPipeline(prometheus.Config{})
+	if err != nil {
+		panic(err)
+	}
+
+	// Expose metrics via HTTP in your handler/muxer
+	http.Handle("/metrics", exporter)
+
+	// When exiting from your process, call Stop for last collection cycle.
+	defer func() {
+		err := exporter.Controller().Stop(context.TODO())
+		if err != nil {
+			panic(err)
+		}
+	}()
+}

exporters/metric/prometheus/prometheus.go

@@ -128,16 +128,6 @@ func NewExportPipeline(config Config, options ...controller.Option) (*Exporter,
 }
 
 // InstallNewPipeline instantiates a NewExportPipeline and registers it globally.
-// Typically called as:
-//
-// 	hf, err := prometheus.InstallNewPipeline(prometheus.Config{...})
-//
-// 	if err != nil {
-// 		...
-// 	}
-// 	http.HandleFunc("/metrics", hf)
-// 	defer pipeline.Stop()
-// 	... Done
 func InstallNewPipeline(config Config, options ...controller.Option) (*Exporter, error) {
 	exp, err := NewExportPipeline(config, options...)
 	if err != nil {