[8.19](backport #47969) fbreceiver: refactor receiver tests for maintainability (#47994)

* fbreceiver: refactor receiver tests for maintainability (#47969)

## Proposed commit message
Changes:
- Refactor TestMultipleReceivers to easily scale to n>2 receivers
- Clean up *.sock files
- Add multiReceiverHelper struct to encapsulate receiver test setup
- Add helper functions: hostFromSocket, writeFile
- Use UUID for socket path generation instead of random bytes
- Use DialContext instead of Dial to fix noctx lint warning

Pulled out from #47870 for easier review.

(cherry picked from commit 135d04f)

# Conflicts:
#	x-pack/filebeat/fbreceiver/receiver_test.go

* Fix conflicts

* fbreceiver: close file in writeFile to fix Windows test (#48019)

On Windows, open file handles prevent t.TempDir() cleanup.
Add defer f.Close() to properly release the file handle.

Fixes test failure introduced in #47969.

---------

Co-authored-by: Orestis Floros <[email protected]>

Author: mergify[bot]

x-pack/filebeat/fbreceiver/receiver_leak_test.go

@@ -6,8 +6,6 @@ package fbreceiver
 
 import (
 	"errors"
-	"path/filepath"
-	"runtime"
 	"testing"
 	"time"
 
@@ -25,13 +23,7 @@ import (
 )
 
 func TestLeak(t *testing.T) {
-	monitorSocket := genSocketPath()
-	var monitorHost string
-	if runtime.GOOS == "windows" {
-		monitorHost = "npipe:///" + filepath.Base(monitorSocket)
-	} else {
-		monitorHost = "unix://" + monitorSocket
-	}
+	monitorHost := hostFromSocket(genSocketPath(t))
 	config := Config{
 		Beatconfig: map[string]any{
 			"filebeat": map[string]any{
@@ -81,7 +73,6 @@ func TestLeak(t *testing.T) {
 		consumeLogs := oteltest.DummyConsumer{ConsumeError: errors.New("cannot publish data")}
 		startAndStopReceiver(t, factory, &consumeLogs, &config)
 	})
-
 }
 
 // StartAndStopReceiver creates a receiver using the provided parameters, starts it, verifies that the expected logs

x-pack/filebeat/fbreceiver/receiver_test.go

@@ -7,11 +7,9 @@ package fbreceiver
 import (
 	"bytes"
 	"context"
-	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
-	"math/rand/v2"
 	"net"
 	"net/http"
 	"net/url"
@@ -21,9 +19,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/elastic/beats/v7/libbeat/otelbeat/oteltest"
-	"github.com/elastic/elastic-agent-libs/mapstr"
-
+	"github.com/gofrs/uuid/v5"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/collector/component"
@@ -32,16 +28,14 @@ import (
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 	"go.uber.org/zap/zaptest/observer"
+
+	"github.com/elastic/beats/v7/libbeat/otelbeat/oteltest"
+	"github.com/elastic/elastic-agent-libs/mapstr"
 )
 
 func TestNewReceiver(t *testing.T) {
-	monitorSocket := genSocketPath()
-	var monitorHost string
-	if runtime.GOOS == "windows" {
-		monitorHost = "npipe:///" + filepath.Base(monitorSocket)
-	} else {
-		monitorHost = "unix://" + monitorSocket
-	}
+	monitorSocket := genSocketPath(t)
+	monitorHost := hostFromSocket(monitorSocket)
 	config := Config{
 		Beatconfig: map[string]any{
 			"filebeat": map[string]any{
@@ -161,149 +155,135 @@ func benchmarkFactoryWithLogLevel(b *testing.B, level zapcore.Level) {
 	}
 }
 
-func TestMultipleReceivers(t *testing.T) {
-	// This test verifies that multiple receivers can be instantiated
-	// in isolation, started, and can ingest logs without interfering
-	// with each other.
-
-	// Receivers need distinct home directories so wrap the config in a function.
-	config := func(monitorSocket string, homePath string, ingestPath string) *Config {
-		var monitorHost string
-		if runtime.GOOS == "windows" {
-			monitorHost = "npipe:///" + filepath.Base(monitorSocket)
-		} else {
-			monitorHost = "unix://" + monitorSocket
-		}
-		return &Config{
-			Beatconfig: map[string]any{
-				"filebeat": map[string]any{
-					"inputs": []map[string]any{
-						{
-							"type":    "benchmark",
-							"enabled": true,
-							"message": "test",
-							"count":   1,
-						},
-						{
-							"type":                 "filestream",
-							"enabled":              true,
-							"id":                   "must-be-unique",
-							"paths":                []string{ingestPath},
-							"file_identity.native": nil,
-						},
+// multiReceiverConfig creates a Config for testing multiple receivers.
+// Each receiver gets a unique home path.
+func multiReceiverConfig(helper multiReceiverHelper) *Config {
+	return &Config{
+		Beatconfig: map[string]any{
+			"filebeat": map[string]any{
+				"inputs": []map[string]any{
+					{
+						"type":    "benchmark",
+						"enabled": true,
+						"message": "test",
+						"count":   1,
 					},
-				},
-				"logging": map[string]any{
-					"level": "info",
-					"selectors": []string{
-						"*",
+					{
+						"type":                 "filestream",
+						"enabled":              true,
+						"id":                   "must-be-unique",
+						"paths":                []string{helper.ingest},
+						"file_identity.native": nil,
 					},
 				},
-				"path.home":    homePath,
-				"http.enabled": true,
-				"http.host":    monitorHost,
 			},
-		}
+			"logging": map[string]any{
+				"level": "info",
+				"selectors": []string{
+					"*",
+				},
+			},
+			"path.home":    helper.home,
+			"http.enabled": true,
+			"http.host":    hostFromSocket(helper.monitorSocket),
+		},
 	}
+}
+
+type multiReceiverHelper struct {
+	name          string
+	home          string
+	ingest        string
+	monitorSocket string
+}
+
+func newMultiReceiverHelper(t *testing.T, number int) multiReceiverHelper {
+	return multiReceiverHelper{
+		name:          fmt.Sprintf("r%d", number),
+		home:          t.TempDir(),
+		ingest:        filepath.Join(t.TempDir(), fmt.Sprintf("test%d.log", number)),
+		monitorSocket: genSocketPath(t),
+	}
+}
+
+// TestMultipleReceivers verifies that multiple receivers can be instantiated in isolation, started, and can ingest logs
+// without interfering with each other.
+func TestMultipleReceivers(t *testing.T) {
+	const nReceivers = 2
 
 	factory := NewFactory()
-	monitorSocket1 := genSocketPath()
-	monitorSocket2 := genSocketPath()
-	dir1 := t.TempDir()
-	dir2 := t.TempDir()
-	ingest1 := filepath.Join(t.TempDir(), "test1.log")
-	ingest2 := filepath.Join(t.TempDir(), "test2.log")
+
+	helpers := make([]multiReceiverHelper, nReceivers)
+	configs := make([]oteltest.ReceiverConfig, nReceivers)
+	for i := range helpers {
+		helper := newMultiReceiverHelper(t, i)
+		helpers[i] = helper
+		configs[i] = oteltest.ReceiverConfig{
+			Name:    helper.name,
+			Beat:    "filebeat",
+			Config:  multiReceiverConfig(helper),
+			Factory: factory,
+		}
+	}
+
 	oteltest.CheckReceivers(oteltest.CheckReceiversParams{
 		T:           t,
 		NumRestarts: 5,
-		Receivers: []oteltest.ReceiverConfig{
-			{
-				Name:    "r1",
-				Beat:    "filebeat",
-				Config:  config(monitorSocket1, dir1, ingest1),
-				Factory: factory,
-			},
-			{
-				Name:    "r2",
-				Beat:    "filebeat",
-				Config:  config(monitorSocket2, dir2, ingest2),
-				Factory: factory,
-			},
-		},
+		Receivers:   configs,
 		AssertFunc: func(c *assert.CollectT, logs map[string][]mapstr.M, zapLogs *observer.ObservedLogs) {
-			// Add data to be ingested with filestream
-			f1, err := os.OpenFile(ingest1, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
-			require.NoError(c, err)
-			_, err = f1.WriteString("A log line\n")
-			require.NoError(c, err)
-			f1.Close()
-			f2, err := os.OpenFile(ingest2, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
-			require.NoError(c, err)
-			_, err = f2.WriteString("A log line\n")
-			require.NoError(c, err)
-			f2.Close()
-
-			require.Greater(c, len(logs["r1"]), 0, "receiver r1 does not have any logs")
-			require.Greater(c, len(logs["r2"]), 0, "receiver r2 does not have any logs")
-
-			assert.Equal(c, "filebeatreceiver/r1", logs["r1"][0].Flatten()["agent.otelcol.component.id"], "expected agent.otelcol.component.id field in r1 log record")
-			assert.Equal(c, "receiver", logs["r1"][0].Flatten()["agent.otelcol.component.kind"], "expected agent.otelcol.component.kind field in r1 log record")
-			assert.Equal(c, "filebeatreceiver/r2", logs["r2"][0].Flatten()["agent.otelcol.component.id"], "expected agent.otelcol.component.id field in r2 log record")
-			assert.Equal(c, "receiver", logs["r2"][0].Flatten()["agent.otelcol.component.kind"], "expected agent.otelcol.component.kind field in r2 log record")
-
-			// Make sure that each receiver has a separate logger
-			// instance and does not interfere with others. Previously, the
-			// logger in Beats was global, causing logger fields to be
-			// overwritten when multiple receivers started in the same process.
-			r1StartLogs := zapLogs.FilterMessageSnippet("Beat ID").FilterField(zap.String("otelcol.component.id", "filebeatreceiver/r1"))
-			assert.Equal(c, 1, r1StartLogs.Len(), "r1 should have a single start log")
-			r2StartLogs := zapLogs.FilterMessageSnippet("Beat ID").FilterField(zap.String("otelcol.component.id", "filebeatreceiver/r2"))
-			assert.Equal(c, 1, r2StartLogs.Len(), "r2 should have a single start log")
-
-			meta1Path := filepath.Join(dir1, "/data/meta.json")
-			assert.FileExists(c, meta1Path, "dir1/data/meta.json should exist")
-			meta1Data, err := os.ReadFile(meta1Path)
-			assert.NoError(c, err)
-
-			meta2Path := filepath.Join(dir2, "/data/meta.json")
-			assert.FileExists(c, meta2Path, "dir2/data/meta.json should exist")
-			meta2Data, err := os.ReadFile(meta2Path)
-			assert.NoError(c, err)
-
-			assert.NotEqual(c, meta1Data, meta2Data, "meta data files should be different")
+			allMetaData := make([]string, 0, nReceivers)
+			allRegData := make([]string, 0, nReceivers)
+			for _, helper := range helpers {
+				writeFile(c, helper.ingest, "A log line")
+
+				require.Greaterf(c, len(logs[helper.name]), 0, "receiver %v does not have any logs", helper)
+
+				assert.Equalf(c, "filebeatreceiver/"+helper.name, logs[helper.name][0].Flatten()["agent.otelcol.component.id"], "expected agent.otelcol.component.id field in %v log record", helper)
+				assert.Equalf(c, "receiver", logs[helper.name][0].Flatten()["agent.otelcol.component.kind"], "expected agent.otelcol.component.kind field in %v log record", helper)
+
+				// Make sure that each receiver has a separate logger
+				// instance and does not interfere with others. Previously, the
+				// logger in Beats was global, causing logger fields to be
+				// overwritten when multiple receivers started in the same process.
+				startLogs := zapLogs.FilterMessageSnippet("Beat ID").FilterField(zap.String("otelcol.component.id", "filebeatreceiver/"+helper.name))
+				assert.Equalf(c, 1, startLogs.Len(), "%v should have a single start log", helper)
+
+				metaPath := filepath.Join(helper.home, "/data/meta.json")
+				assert.FileExistsf(c, metaPath, "%s of %v should exist", metaPath, helper)
+				metaData, err := os.ReadFile(metaPath)
+				assert.NoError(c, err)
+				allMetaData = append(allMetaData, string(metaData))
+
+				var lastError strings.Builder
+				assert.Conditionf(c, func() bool {
+					return getFromSocket(t, &lastError, helper.monitorSocket, "stats")
+				}, "failed to connect to monitoring socket of %v, stats endpoint, last error was: %s", helper, &lastError)
+				assert.Conditionf(c, func() bool {
+					return getFromSocket(t, &lastError, helper.monitorSocket, "inputs")
+				}, "failed to connect to monitoring socket of %v, inputs endpoint, last error was: %s", helper, &lastError)
+
+				ingestJson, err := json.Marshal(helper.ingest)
+				assert.NoError(c, err)
+
+				regPath := filepath.Join(helper.home, "/data/registry/filebeat/log.json")
+				assert.FileExistsf(c, regPath, "receiver %v filebeat registry should exist", helper)
+				regData, err := os.ReadFile(regPath)
+				allRegData = append(allRegData, string(regData))
+				assert.NoError(c, err)
+				assert.Containsf(c, string(regData), string(ingestJson), "receiver %v registry should contain '%s', but was: %s", helper, string(ingestJson), string(regData))
+			}
 
-			var lastError strings.Builder
-			assert.Conditionf(c, func() bool {
-				return getFromSocket(t, &lastError, monitorSocket1, "stats")
-			}, "failed to connect to monitoring socket1, stats endpoint, last error was: %s", &lastError)
-			assert.Conditionf(c, func() bool {
-				return getFromSocket(t, &lastError, monitorSocket1, "inputs")
-			}, "failed to connect to monitoring socket1, inputs endpoint, last error was: %s", &lastError)
-			assert.Conditionf(c, func() bool {
-				return getFromSocket(t, &lastError, monitorSocket2, "stats")
-			}, "failed to connect to monitoring socket2, stats endpoint, last error was: %s", &lastError)
-			assert.Conditionf(c, func() bool {
-				return getFromSocket(t, &lastError, monitorSocket2, "inputs")
-			}, "failed to connect to monitoring socket2, inputs endpoint, last error was: %s", &lastError)
-
-			ingest1Json, err := json.Marshal(ingest1)
-			require.NoError(c, err)
-			ingest2Json, err := json.Marshal(ingest2)
-			require.NoError(c, err)
-
-			reg1Path := filepath.Join(dir1, "/data/registry/filebeat/log.json")
-			require.FileExists(c, reg1Path, "receiver 1 filebeat registry should exist")
-			reg1Data, err := os.ReadFile(reg1Path)
-			require.NoError(c, err)
-			require.Containsf(c, string(reg1Data), string(ingest1Json), "receiver 1 registry should contain '%s', but was: %s", string(ingest1Json), string(reg1Data))
-			require.NotContainsf(c, string(reg1Data), string(ingest2Json), "receiver 1 registry should not contain '%s', but was: %s", string(ingest2Json), string(reg1Data))
-
-			reg2Path := filepath.Join(dir2, "/data/registry/filebeat/log.json")
-			require.FileExists(c, reg2Path, "receiver 2 filebeat registry should exist")
-			reg2Data, err := os.ReadFile(reg2Path)
-			require.NoError(c, err)
-			require.Containsf(c, string(reg2Data), string(ingest2Json), "receiver 2 registry should contain '%s', but was: %s", string(ingest2Json), string(reg2Data))
-			require.NotContainsf(c, string(reg2Data), string(ingest1Json), "receiver 2 registry should not contain '%s', but was: %s", string(ingest1Json), string(reg2Data))
+			for i := range nReceivers {
+				for j := range nReceivers {
+					if i == j {
+						continue
+					}
+					h1 := helpers[i]
+					h2 := helpers[j]
+					assert.NotEqualf(c, allMetaData[i], allMetaData[j], "meta data files between %v and %v should be different", h1, h2)
+					assert.NotContainsf(c, allRegData[i], allRegData[j], "receiver %v registry should not contain data from %v registry", h1, h2)
+				}
+			}
 		},
 	})
 }
@@ -379,14 +359,14 @@ func TestReceiverDegraded(t *testing.T) {
 	}
 }
 
-func genSocketPath() string {
-	randData := make([]byte, 16)
-	for i := range len(randData) {
-		randData[i] = uint8(rand.UintN(255)) //nolint:gosec // 0-255 fits in a uint8
-	}
-	socketName := base64.URLEncoding.EncodeToString(randData) + ".sock"
-	socketDir := os.TempDir()
-	return filepath.Join(socketDir, socketName)
+func genSocketPath(t *testing.T) string {
+	t.Helper()
+	socketName, err := uuid.NewV4()
+	require.NoError(t, err)
+	// Use os.TempDir() for short Unix socket paths
+	sockPath := filepath.Join(os.TempDir(), socketName.String()+".sock")
+	t.Cleanup(func() { _ = os.Remove(sockPath) })
+	return sockPath
 }
 
 func getFromSocket(t *testing.T, sb *strings.Builder, socketPath string, endpoint string) bool {
@@ -396,8 +376,8 @@ func getFromSocket(t *testing.T, sb *strings.Builder, socketPath string, endpoin
 	}
 	client := http.Client{
 		Transport: &http.Transport{
-			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
-				return net.Dial("unix", socketPath)
+			DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
+				return (&net.Dialer{}).DialContext(ctx, "unix", socketPath)
 			},
 		},
 	}
@@ -493,3 +473,18 @@ func TestReceiverHook(t *testing.T) {
 	// 	one for beat metrics, one for input metrics and one for getting the registry.
 	oteltest.TestReceiverHook(t, &cfg, NewFactory(), receiverSettings, 3)
 }
+
+func hostFromSocket(socket string) string {
+	if runtime.GOOS == "windows" {
+		return "npipe:///" + filepath.Base(socket)
+	}
+	return "unix://" + socket
+}
+
+func writeFile(t require.TestingT, path string, data string) {
+	f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
+	require.NoErrorf(t, err, "Could not open file %s", path)
+	defer f.Close()
+	_, err = f.WriteString(data + "\n")
+	require.NoErrorf(t, err, "Could not write %s to file %s", data, path)
+}