test(testutil): Improve performance and code quality (#17022)

Author: skartikey

testutil/testutil.go

@@ -16,8 +16,6 @@ import (
 	"github.com/influxdata/telegraf/plugins/serializers/influx"
 )
 
-var localhost = "localhost"
-
 const (
 	DefaultDelta   = 0.001
 	DefaultEpsilon = 0.1
@@ -26,21 +24,22 @@ const (
 // GetLocalHost returns the DOCKER_HOST environment variable, parsing
 // out any scheme or ports so that only the IP address is returned.
 func GetLocalHost() string {
-	if dockerHostVar := os.Getenv("DOCKER_HOST"); dockerHostVar != "" {
-		u, err := url.Parse(dockerHostVar)
-		if err != nil {
-			return dockerHostVar
-		}
-
-		// split out the ip addr from the port
-		host, _, err := net.SplitHostPort(u.Host)
-		if err != nil {
-			return dockerHostVar
-		}
-
-		return host
+	dockerHostVar := os.Getenv("DOCKER_HOST")
+	if dockerHostVar == "" {
+		return "localhost"
+	}
+
+	u, err := url.Parse(dockerHostVar)
+	if err != nil {
+		return dockerHostVar
+	}
+
+	host, _, err := net.SplitHostPort(u.Host)
+	if err != nil {
+		return dockerHostVar
 	}
-	return localhost
+
+	return host
 }
 
 // GetRandomString returns a random alphanumerical string of the given length.
@@ -49,32 +48,23 @@ func GetLocalHost() string {
 // host which might be drained e.g. in CI pipelines. This is useful to e.g.
 // create random passwords for tests where security is not a concern.
 func GetRandomString(chars int) string {
-	charset := []byte("abcdefghijklmnopqrstABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
-
-	nchars := len(charset)
+	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 	buffer := make([]byte, chars)
-	for i := range chars {
+	for i := range buffer {
 		//nolint:gosec // Using a weak random number generator on purpose to not drain entropy
-		buffer[i] = charset[rand.Intn(nchars)]
+		buffer[i] = charset[rand.Intn(len(charset))]
 	}
-
 	return string(buffer)
 }
 
 // MockMetrics returns a mock []telegraf.Metric object for using in unit tests
 // of telegraf output sinks.
 func MockMetrics() []telegraf.Metric {
-	metrics := make([]telegraf.Metric, 0)
-	// Create a new point batch
-	metrics = append(metrics, TestMetric(1.0))
-	return metrics
+	return []telegraf.Metric{TestMetric(1.0)}
 }
 
 func MockMetricsWithValue(value float64) []telegraf.Metric {
-	metrics := make([]telegraf.Metric, 0)
-	// Create a new point batch
-	metrics = append(metrics, TestMetric(value))
-	return metrics
+	return []telegraf.Metric{TestMetric(value)}
 }
 
 // TestMetric Returns a simple test point:
@@ -91,20 +81,21 @@ func TestMetric(value interface{}, name ...string) telegraf.Metric {
 	if len(name) > 0 {
 		measurement = name[0]
 	}
-	tags := map[string]string{"tag1": "value1"}
-	pt := metric.New(
+
+	return metric.New(
 		measurement,
-		tags,
+		map[string]string{"tag1": "value1"},
 		map[string]interface{}{"value": value},
 		time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC),
 	)
-	return pt
 }
 
 // OnlyTags returns an option for keeping only "Tags" for a given Metric
 func OnlyTags() cmp.Option {
-	f := func(p cmp.Path) bool { return p.String() != "Tags" && p.String() != "" }
-	return cmp.FilterPath(f, cmp.Ignore())
+	return cmp.FilterPath(func(p cmp.Path) bool {
+		path := p.String()
+		return path != "Tags" && path != ""
+	}, cmp.Ignore())
 }
 
 func PrintMetrics(m []telegraf.Metric) {
@@ -130,8 +121,5 @@ func DefaultSampleConfig(sampleConfig string) []byte {
 }
 
 func WithinDefaultDelta(dt float64) bool {
-	if dt < -DefaultDelta || dt > DefaultDelta {
-		return false
-	}
-	return true
+	return dt >= -DefaultDelta && dt <= DefaultDelta
 }

testutil/testutil_test.go

@@ -14,7 +14,7 @@ func TestDockerHost(t *testing.T) {
 
 		host := GetLocalHost()
 
-		if host != localhost {
+		if host != "localhost" {
 			t.Fatalf("Host should be localhost when DOCKER_HOST is not set. Current value [%s]", host)
 		}
 	})