Refactor collectors

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

pkg/testutils/testutils.go

@@ -0,0 +1,38 @@
+//go:build windows
+
+package testutils
+
+import (
+	"testing"
+
+	"github.com/alecthomas/kingpin/v2"
+	"github.com/go-kit/log"
+	"github.com/prometheus-community/windows_exporter/pkg/collector"
+	"github.com/prometheus-community/windows_exporter/pkg/types"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/require"
+)
+
+func FuncBenchmarkCollector(b *testing.B, name string, collectFunc types.CollectorBuilderWithFlags) {
+	c := collectFunc(kingpin.CommandLine)
+	collectors := collector.New(map[string]types.Collector{name: c})
+	require.NoError(b, collectors.Build())
+	collectors.SetLogger(log.NewNopLogger())
+
+	// Create perflib scrape context.
+	// Some perflib collectors required a correct context,
+	// or will fail during benchmark.
+	scrapeContext, err := collectors.PrepareScrapeContext()
+	require.NoError(b, err)
+
+	metrics := make(chan prometheus.Metric)
+	go func() {
+		for {
+			<-metrics
+		}
+	}()
+
+	for i := 0; i < b.N; i++ {
+		require.NoError(b, c.Collect(scrapeContext, metrics))
+	}
+}