Add libgit2 checkout test with ED25519 key

This adds a test to detect any regression in libgit2's ED25519 key
support. go-git supports ED25519 but not the current version of
libgit2 used in flux. The updates to libgit2 in v1.2.0 adds support
for ED25519. This test would help ensure the right version of libgit2
is used.

Signed-off-by: Sunny <darkowlzz@protonmail.com>
Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

Author: Paulo Gomes

pkg/git/libgit2/checkout_test.go

@@ -20,13 +20,19 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net/url"
 	"os"
 	"path/filepath"
 	"testing"
 	"time"
 
+	"github.com/fluxcd/pkg/gittestserver"
+	"github.com/fluxcd/pkg/ssh"
 	git2go "github.com/libgit2/git2go/v33"
 	. "github.com/onsi/gomega"
+	corev1 "k8s.io/api/core/v1"
+
+	"github.com/fluxcd/source-controller/pkg/git"
 )
 
 func TestCheckoutBranch_Checkout(t *testing.T) {
@@ -444,3 +450,68 @@ func mockSignature(time time.Time) *git2go.Signature {
 		When:  time,
 	}
 }
+
+// This test is specifically to detect regression in libgit2's ED25519 key
+// support for client authentication.
+// Refer: https://github.com/fluxcd/source-controller/issues/399
+func TestCheckout_ED25519(t *testing.T) {
+	g := NewWithT(t)
+	timeout := 5 * time.Second
+
+	// Create a git test server.
+	server, err := gittestserver.NewTempGitServer()
+	g.Expect(err).ToNot(HaveOccurred())
+	defer os.RemoveAll(server.Root())
+	server.Auth("test-user", "test-pswd")
+	server.AutoCreate()
+
+	server.KeyDir(filepath.Join(server.Root(), "keys"))
+	g.Expect(server.ListenSSH()).To(Succeed())
+
+	go func() {
+		server.StartSSH()
+	}()
+	defer server.StopSSH()
+
+	repoPath := "test.git"
+
+	err = server.InitRepo("testdata/git/repo", git.DefaultBranch, repoPath)
+	g.Expect(err).NotTo(HaveOccurred())
+
+	sshURL := server.SSHAddress()
+	repoURL := sshURL + "/" + repoPath
+
+	// Fetch host key.
+	u, err := url.Parse(sshURL)
+	g.Expect(err).NotTo(HaveOccurred())
+	g.Expect(u.Host).ToNot(BeEmpty())
+	knownHosts, err := ssh.ScanHostKey(u.Host, timeout)
+	g.Expect(err).ToNot(HaveOccurred())
+
+	kp, err := ssh.NewEd25519Generator().Generate()
+	g.Expect(err).ToNot(HaveOccurred())
+
+	secret := corev1.Secret{
+		Data: map[string][]byte{
+			"identity":    kp.PrivateKey,
+			"known_hosts": knownHosts,
+		},
+	}
+
+	authOpts, err := git.AuthOptionsFromSecret(repoURL, &secret)
+	g.Expect(err).ToNot(HaveOccurred())
+
+	// Prepare for checkout.
+	branchCheckoutStrat := &CheckoutBranch{Branch: git.DefaultBranch}
+	tmpDir, _ := os.MkdirTemp("", "test")
+	defer os.RemoveAll(tmpDir)
+
+	ctx, cancel := context.WithTimeout(context.TODO(), timeout)
+	defer cancel()
+
+	// Checkout the repo.
+	// This should always fail because the generated key above isn't present in
+	// the git server.
+	_, err = branchCheckoutStrat.Checkout(ctx, tmpDir, repoURL, authOpts)
+	g.Expect(err).To(BeNil())
+}

pkg/git/libgit2/testdata/git/repo/foo.txt

@@ -0,0 +1 @@
+test file