[8.9](backport #2955) Introduce upgrade tests from released versions (#…

…3173)

This is an automatic backport of pull request #2955 done by
[Mergify](https://mergify.com).
---------

Co-authored-by: Paolo Chilà <paolo.chila@elastic.co>

pkg/testing/fixture.go

@@ -42,7 +42,8 @@ type Fixture struct {
 	allowErrs       bool
 	connectTimout   time.Duration
 
-	workDir string
+	srcPackage string
+	workDir    string
 
 	installed   bool
 	installOpts *InstallOpts
@@ -153,6 +154,7 @@ func (f *Fixture) Prepare(ctx context.Context, components ...UsableComponent) er
 	if err != nil {
 		return err
 	}
+	f.srcPackage = src
 	filename := filepath.Base(src)
 	name, _, err := splitFileType(filename)
 	if err != nil {
@@ -191,6 +193,15 @@ func (f *Fixture) WorkDir() string {
 	return f.workDir
 }
 
+// SrcPackage returns the location on disk of the elastic agent package used by this fixture.
+func (f *Fixture) SrcPackage(ctx context.Context) (string, error) {
+	err := f.ensurePrepared(ctx)
+	if err != nil {
+		return "", err
+	}
+	return f.srcPackage, nil
+}
+
 func ExtractArtifact(l Logger, artifactFile, outputDir string) error {
 	filename := filepath.Base(artifactFile)
 	_, ext, err := splitFileType(filename)

pkg/testing/tools/cmd.go

@@ -11,15 +11,7 @@ import (
 )
 
 // InstallAgent force install the Elastic Agent through agentFixture.
-func InstallAgent(fleetUrl string, enrollmentToken string, agentFixture *atesting.Fixture) ([]byte, error) {
-	installOpts := atesting.InstallOpts{
-		NonInteractive: true,
-		Force:          true,
-		EnrollOpts: atesting.EnrollOpts{
-			URL:             fleetUrl,
-			EnrollmentToken: enrollmentToken,
-		},
-	}
+func InstallAgent(installOpts atesting.InstallOpts, agentFixture *atesting.Fixture) ([]byte, error) {
 	return agentFixture.Install(context.Background(), &installOpts)
 }
 

pkg/testing/tools/tools.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/elastic/elastic-agent-libs/kibana"
+
 	atesting "github.com/elastic/elastic-agent/pkg/testing"
 
 	"github.com/stretchr/testify/require"
@@ -79,7 +80,17 @@ func InstallAgentWithPolicy(t *testing.T, agentFixture *atesting.Fixture, kibCli
 
 	// Enroll agent
 	t.Logf("Unpacking and installing Elastic Agent")
-	output, err := InstallAgent(fleetServerURL, enrollmentToken.APIKey, agentFixture)
+	// this is a partial backport of https://github.com/elastic/elastic-agent/pull/3114
+	// normally the installOpts are passed as parameter, and we just add URL and Enrollment Token
+	installOpts := atesting.InstallOpts{
+		NonInteractive: true,
+		Force:          true,
+	}
+	installOpts.EnrollOpts = atesting.EnrollOpts{
+		URL:             fleetServerURL,
+		EnrollmentToken: enrollmentToken.APIKey,
+	}
+	output, err := InstallAgent(installOpts, agentFixture)
 	if err != nil {
 		t.Log(string(output))
 		return nil, fmt.Errorf("unable to enroll Elastic Agent: %w", err)