[chore][receiver/sshcheck] Enable goleak check (#32181)

This enables `goleak` checks for the sshcheck receiver to help ensure no
goroutines are being leaked. This is a test only change. The test
package's SSH Server needed to be modified to properly shutdown.

**Link to tracking Issue:** #30438

receiver/sshcheckreceiver/package_test.go

@@ -0,0 +1,14 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package sshcheckreceiver
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}

receiver/sshcheckreceiver/scraper_test.go

@@ -24,7 +24,24 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest/pmetrictest"
 )
 
-func setupSSHServer(t *testing.T) string {
+type sshServer struct {
+	listener net.Listener
+	done     chan struct{}
+}
+
+func newSSHServer(network, endpoint string) (*sshServer, error) {
+	listener, err := net.Listen(network, endpoint)
+	if err != nil {
+		return nil, err
+	}
+
+	return &sshServer{
+		listener: listener,
+		done:     make(chan struct{}),
+	}, nil
+}
+
+func (s *sshServer) runSSHServer(t *testing.T) string {
 	config := &ssh.ServerConfig{
 		NoClientAuth: true,
 		PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
@@ -43,14 +60,16 @@ func setupSSHServer(t *testing.T) string {
 
 	config.AddHostKey(private)
 
-	listener, err := net.Listen("tcp", "127.0.0.1:0")
-	require.NoError(t, err)
-
 	go func() {
 		for {
-			conn, err := listener.Accept()
+			conn, err := s.listener.Accept()
 			if err != nil {
-				break
+				select {
+				case <-s.done:
+					return
+				default:
+					require.NoError(t, err)
+				}
 			}
 			_, chans, reqs, err := ssh.NewServerConn(conn, config)
 			if err != nil {
@@ -62,7 +81,12 @@ func setupSSHServer(t *testing.T) string {
 		}
 	}()
 
-	return listener.Addr().String()
+	return s.listener.Addr().String()
+}
+
+func (s *sshServer) shutdown() {
+	close(s.done)
+	s.listener.Close()
 }
 
 func handleChannels(chans <-chan ssh.NewChannel) {
@@ -116,8 +140,12 @@ func TestScraper(t *testing.T) {
 	if !supportedOS() {
 		t.Skip("Skip tests if not running on one of: [linux, darwin, freebsd, openbsd]")
 	}
-	endpoint := setupSSHServer(t)
+
+	s, err := newSSHServer("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	endpoint := s.runSSHServer(t)
 	require.NotEmpty(t, endpoint)
+	defer s.shutdown()
 
 	testCases := []struct {
 		name       string
@@ -187,8 +215,11 @@ func TestScraperPropagatesResourceAttributes(t *testing.T) {
 	if !supportedOS() {
 		t.Skip("Skip tests if not running on one of: [linux, darwin, freebsd, openbsd]")
 	}
-	endpoint := setupSSHServer(t)
+	s, err := newSSHServer("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	endpoint := s.runSSHServer(t)
 	require.NotEmpty(t, endpoint)
+	defer s.shutdown()
 
 	f := NewFactory()
 	cfg := f.CreateDefaultConfig().(*Config)
@@ -223,8 +254,11 @@ func TestScraperDoesNotErrForSSHErr(t *testing.T) {
 	if !supportedOS() {
 		t.Skip("Skip tests if not running on one of: [linux, darwin, freebsd, openbsd]")
 	}
-	endpoint := setupSSHServer(t)
+	s, err := newSSHServer("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	endpoint := s.runSSHServer(t)
 	require.NotEmpty(t, endpoint)
+	defer s.shutdown()
 
 	f := NewFactory()
 	cfg := f.CreateDefaultConfig().(*Config)
@@ -239,7 +273,7 @@ func TestScraperDoesNotErrForSSHErr(t *testing.T) {
 	scraper := newScraper(cfg, settings)
 	require.NoError(t, scraper.start(context.Background(), componenttest.NewNopHost()), "should not err to start")
 
-	_, err := scraper.scrape(context.Background())
+	_, err = scraper.scrape(context.Background())
 	require.NoError(t, err, "should not err")
 }