[chore][prometheusreceiver]: safer and quicker tests (open-telemetry#43906)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Some tests set the global registry to enable
native histograms, which is not safe for t.Parallel().

Fix this by only using the feature gate in the receiver factory.

This makes TestNativeVsClassicHistogramScrapeViaProtobuf 4x faster on my
laptop.

Signed-off-by: György Krajcsovits <[email protected]>

Author: krajorama

receiver/prometheusreceiver/config.go

@@ -47,6 +47,9 @@ type Config struct {
 	// server in agent mode. This allows the user to call the endpoint to get
 	// the config, service discovery, and targets for debugging purposes.
 	APIServer APIServer `mapstructure:"api_server"`
+
+	// From feature gate.
+	enableNativeHistograms bool
 }
 
 // Validate checks the receiver configuration is valid.

receiver/prometheusreceiver/factory.go

@@ -63,6 +63,7 @@ func createMetricsReceiver(
 	nextConsumer consumer.Metrics,
 ) (receiver.Metrics, error) {
 	configWarnings(set.Logger, cfg.(*Config))
+	cfg.(*Config).enableNativeHistograms = enableNativeHistogramsGate.IsEnabled()
 	return newPrometheusReceiver(set, cfg.(*Config), nextConsumer)
 }
 

receiver/prometheusreceiver/metrics_receiver.go

@@ -98,7 +98,7 @@ func newPrometheusReceiver(set receiver.Settings, cfg *Config, next consumer.Met
 			set,
 			cfg.TargetAllocator.Get(),
 			&baseCfg,
-			enableNativeHistogramsGate.IsEnabled(),
+			cfg.enableNativeHistograms,
 		),
 	}
 	return pr, nil
@@ -176,7 +176,7 @@ func (r *pReceiver) initPrometheusComponents(ctx context.Context, logger *slog.L
 		r.cfg.UseStartTimeMetric,
 		startTimeMetricRegex,
 		useCreatedMetricGate.IsEnabled(),
-		enableNativeHistogramsGate.IsEnabled(),
+		r.cfg.enableNativeHistograms,
 		r.cfg.PrometheusConfig.GlobalConfig.ExternalLabels,
 		r.cfg.TrimMetricSuffixes,
 	)
@@ -231,7 +231,7 @@ func (r *pReceiver) initScrapeOptions() *scrape.Options {
 			commonconfig.WithUserAgent(r.settings.BuildInfo.Command + "/" + r.settings.BuildInfo.Version),
 		},
 		EnableCreatedTimestampZeroIngestion: enableCreatedTimestampZeroIngestionGate.IsEnabled(),
-		EnableNativeHistogramsIngestion:     enableNativeHistogramsGate.IsEnabled(),
+		EnableNativeHistogramsIngestion:     r.cfg.enableNativeHistograms,
 	}
 
 	return opts

receiver/prometheusreceiver/metrics_receiver_protobuf_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/prometheus/prometheus/config"
 	dto "github.com/prometheus/prometheus/prompb/io/prometheus/client"
 	"github.com/stretchr/testify/require"
-	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/pdata/pmetric"
 )
 
@@ -496,14 +495,9 @@ func TestNativeVsClassicHistogramScrapeViaProtobuf(t *testing.T) {
 		},
 	}
 
-	defer func() {
-		_ = featuregate.GlobalRegistry().Set("receiver.prometheusreceiver.EnableNativeHistograms", false)
-	}()
-
 	for name, tc := range testCases {
 		t.Run(name, func(t *testing.T) {
-			err := featuregate.GlobalRegistry().Set("receiver.prometheusreceiver.EnableNativeHistograms", tc.enableNativeHistograms)
-			require.NoError(t, err)
+			t.Parallel()
 
 			targets := []*testData{
 				{
@@ -522,6 +516,7 @@ func TestNativeVsClassicHistogramScrapeViaProtobuf(t *testing.T) {
 				mutCfg = func(*PromConfig) {}
 			}
 			testComponent(t, targets, func(c *Config) {
+				c.enableNativeHistograms = tc.enableNativeHistograms
 				c.PrometheusConfig.GlobalConfig.ScrapeProtocols = []config.ScrapeProtocol{config.PrometheusProto}
 			}, mutCfg)
 		})
@@ -650,12 +645,9 @@ func TestStaleExponentialHistogram(t *testing.T) {
 			},
 		},
 	}
-	err := featuregate.GlobalRegistry().Set("receiver.prometheusreceiver.EnableNativeHistograms", true)
-	require.NoError(t, err)
-	defer func() {
-		_ = featuregate.GlobalRegistry().Set("receiver.prometheusreceiver.EnableNativeHistograms", false)
-	}()
+
 	testComponent(t, targets, func(c *Config) {
+		c.enableNativeHistograms = true
 		c.PrometheusConfig.GlobalConfig.ScrapeProtocols = []config.ScrapeProtocol{config.PrometheusProto}
 	})
 }
@@ -715,12 +707,9 @@ func TestFloatCounterHistogram(t *testing.T) {
 			},
 		},
 	}
-	err := featuregate.GlobalRegistry().Set("receiver.prometheusreceiver.EnableNativeHistograms", true)
-	require.NoError(t, err)
-	defer func() {
-		_ = featuregate.GlobalRegistry().Set("receiver.prometheusreceiver.EnableNativeHistograms", false)
-	}()
+
 	testComponent(t, targets, func(c *Config) {
+		c.enableNativeHistograms = true
 		c.PrometheusConfig.GlobalConfig.ScrapeProtocols = []config.ScrapeProtocol{config.PrometheusProto}
 	})
 }