feat: add more tests to increase coverage

internal/cert/root_ca_test.go

@@ -1,6 +1,7 @@
 package cert
 
 import (
+	"crypto/ecdsa"
 	"crypto/elliptic"
 	"crypto/x509"
 	"math/big"
@@ -52,7 +53,7 @@ func Test_newPrivateKey(t *testing.T) {
 	require.NoError(t, err)
 
 	require.NotEmpty(t, privKey.PublicKey.Params().Name)
-	require.Equal(t, elliptic.P256(), privKey.PublicKey.Params().Name)
+	require.Equal(t, elliptic.P256().Params().Name, privKey.PublicKey.Params().Name)
 }
 
 func Test_encodePrivateKey(t *testing.T) {
@@ -66,6 +67,12 @@ func Test_encodePrivateKey(t *testing.T) {
 	require.Greater(t, len(bytes), 0)
 }
 
+func Test_encodePrivateKeyError(t *testing.T) {
+	key := ecdsa.PrivateKey{}
+	_, err := encodePrivateKey(&key)
+	require.Error(t, err)
+}
+
 func Test_newRootCA(t *testing.T) {
 	caPEM, keyPEM, err := newRootCA(&rootTestConfig)
 
@@ -88,12 +95,22 @@ func Test_parseCertificate(t *testing.T) {
 	require.Equal(t, rootCert.Issuer.CommonName, rootTestConfig.Subject.CommonName)
 }
 
+func Test_parseCertificateError(t *testing.T) {
+	_, err := parseCertificate([]byte{})
+	require.Error(t, err)
+}
+
 func TestNewRootCA(t *testing.T) {
 	rootCert, err := NewRootCA(&rootTestConfig)
 	require.NoError(t, err)
 	require.NotNil(t, rootCert)
 }
 
+func TestNewRootCAERror(t *testing.T) {
+	_, err := NewRootCA(nil)
+	require.Error(t, err)
+}
+
 func Test_rootCA_WithClientCert(t *testing.T) {
 	rootCert, err := NewRootCA(&rootTestConfig)
 	require.NoError(t, err)