test(ssh): cover FindPrivateKeys edge cases

pkg/ssh/ssh_add_test.go

@@ -0,0 +1,53 @@
+package ssh
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFindPrivateKeys_MissingSSHDirReturnsError(t *testing.T) {
+	t.Setenv("HOME", t.TempDir())
+
+	_, err := FindPrivateKeys()
+	require.Error(t, err, "a missing .ssh directory must surface a read error")
+}
+
+func TestFindPrivateKeys_ReturnsOnlyValidPrivateKeys(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	sshDir := filepath.Join(home, ".ssh")
+	require.NoError(t, os.MkdirAll(sshDir, 0o700))
+
+	privKey, _, err := rsaKeyGen()
+	require.NoError(t, err)
+	privPath := filepath.Join(sshDir, "id_ed25519")
+	require.NoError(t, os.WriteFile(privPath, []byte(privKey), 0o600))
+
+	// Public keys, config files, and subdirectories are not private keys and
+	// must not be returned, even when they live alongside a valid key.
+	require.NoError(t, os.WriteFile(
+		filepath.Join(sshDir, "id_ed25519.pub"), []byte("ssh-ed25519 AAAAfake test"), 0o600))
+	require.NoError(t, os.WriteFile(filepath.Join(sshDir, "config"), []byte("Host *\n"), 0o600))
+	require.NoError(t, os.MkdirAll(filepath.Join(sshDir, "subdir"), 0o700))
+
+	keys, err := FindPrivateKeys()
+	require.NoError(t, err)
+	assert.Equal(t, []string{privPath}, keys,
+		"only parseable private keys should be returned")
+}
+
+func TestFindPrivateKeys_EmptySSHDirReturnsNoKeys(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	require.NoError(t, os.MkdirAll(filepath.Join(home, ".ssh"), 0o700))
+
+	keys, err := FindPrivateKeys()
+	require.NoError(t, err)
+	assert.Empty(t, keys, "an empty .ssh directory must yield no keys")
+}