feat: load env from file

.gitignore

@@ -1,3 +1,5 @@
 .env
 viper.default.yaml
 .vscode
+certs
+coverage

LICENSE

@@ -0,0 +1,8 @@
+---- Definitions ----
+license means right to use
+
+
+Everybody is invited to contribute to improve this project and the main idea.
+This idea which is to help the community to develop more secure code.
+
+By the grace of YAHWEH

Makefile

@@ -1,6 +1,13 @@
+COVERAGE_DIR=coverage
+
 lint:
 	golangci-lint run ./...
 goreportcard:
 	goreportcard-cli -v
 test: 
 	go test ./...
+test-coverage:
+	rm -rf ${COVERAGE_DIR}
+	mkdir ${COVERAGE_DIR}
+	go test -v -coverprofile ${COVERAGE_DIR}/cover.out ./...
+	go tool cover -html ${COVERAGE_DIR}/cover.out -o ${COVERAGE_DIR}/cover.html

README.md

@@ -8,7 +8,7 @@ I had some trouble during TLS communication between both of my gRPC server and c
 ## TODO:
 - [ ] Create intermediate authority to sign certificates on behalf CA to add more security. If intermediate is hacked then you can revoke from CA and generate new intermediates keeping CA isolated from beeing hacked.
 
-- [ ] Complete tests
+- ~~[x] Complete tests~~
 
 ## Configuration
 If you are on `dev` environment, like I've been doing, you must create `.env` file similar as `.env.example` in this repo:
@@ -31,7 +31,7 @@ ca:
     ext_key_usage: 
         - 1
         - 2
-        duration: 518400 #1 year
+        duration: "8760h0m0s" #1 year
 client:
     serial_number: 12151232 # serial number
     subject:
@@ -51,7 +51,7 @@ client:
     ext_key_usage: 
         - 1
         - 2
-    duration: 518400
+    duration: "8760h0m0s"
 ```
 ## Execution
 Then you can just run 
@@ -59,21 +59,37 @@ Then you can just run
 go run main.go
 ```
 
+## tests
+Just simply run make command and watch coverage results on `cover.html` within `coverage` 
+```shell
+make test-coverage
+rm -rf coverage
+mkdir coverage
+go test -v -coverprofile coverage/cover.out ./...
+=== RUN   TestCredentialsFromKeyWithPasswd
+--- PASS: TestCredentialsFromKeyWithPasswd (0.37s)
+=== RUN   TestCredentialsFromKeyWithPasswdError
+--- PASS: TestCredentialsFromKeyWithPasswdError (0.46s)
+PASS
+coverage: 90.9% of statements
+ok      gitea.urkob.com/urko/go-grpc-certificate/pkg/credentials        0.839s  coverage: 90.9% of statements
+go tool cover -html coverage/cover.out -o coverage/cover.html
+```
+
 ## goreportcard
 ```bash
 make goreportcard
 ```
 output:
 ```bash
-goreportcard-cli -v
-Grade ........... A+ 94.1%
-Files .................. 9
-Issues ................. 1
+➜  go-cert-gen git:(main) goreportcard-cli -v
+Grade .......... A+ 100.0%
+Files ................. 12
+Issues ................. 0
 gofmt ............... 100%
 go_vet .............. 100%
 gocyclo ............. 100%
 ineffassign ......... 100%
-license ............... 0%
-
+license ............. 100%
 misspell ............ 100%
 ```

cmd/main.go

@@ -27,9 +27,9 @@ var envConfig struct {
 
 var writer pkgio.WriterIface
 
-func intEnvConfig(isProd bool) {
-	if !isProd {
-		err := godotenv.Load(util.RootDir() + "/.env")
+func intEnvConfig(envFilePath string) {
+	if envFilePath != "" {
+		err := godotenv.Load(envFilePath)
 		if err != nil {
 			log.Fatalf("environment variable ENV is empty and an error occurred while loading the .env file: %s\n", err)
 		}
@@ -87,32 +87,59 @@ var rootCmd = &cobra.Command{
 			log.Fatalf("rootCA.WithClientCert: %s", err)
 		}
 
-		exportPem("root-ca.pem", rootCA.PEM())
-		exportPem("root-key.pem", rootCA.Key())
+		outputPath, err := exportPem("root-ca.pem", rootCA.PEM())
+		if err != nil {
+			log.Fatalf("exportPem: %s\n", err)
+		}
+		log.Printf("file created successfully: %s\n", outputPath)
 
-		exportPem("client-cert.pem", clientCert.PEM())
-		exportPem("client-key.pem", clientCert.Key())
+		outputPath, err = exportPem("root-key.pem", rootCA.Key())
+		if err != nil {
+			log.Fatalf("exportPem: %s\n", err)
+		}
+		log.Printf("file created successfully: %s\n", outputPath)
+
+		outputPath, err = exportPem("client-cert.pem", clientCert.PEM())
+		if err != nil {
+			log.Fatalf("exportPem: %s\n", err)
+		}
+		log.Printf("file created successfully: %s\n", outputPath)
+
+		outputPath, err = exportPem("client-key.pem", clientCert.Key())
+		if err != nil {
+			log.Fatalf("exportPem: %s\n", err)
+		}
+		log.Printf("file created successfully: %s\n", outputPath)
 	},
 }
 
 func getExtKeyUsage(intKeyUsageSlice []int) []x509.ExtKeyUsage {
-	extKeyUsage := make([]x509.ExtKeyUsage, len(intKeyUsageSlice))
+	if intKeyUsageSlice == nil || len(intKeyUsageSlice) <= 0 {
+		return []x509.ExtKeyUsage{}
+	}
+
+	extKeyUsage := make([]x509.ExtKeyUsage, 0, len(intKeyUsageSlice))
 	for _, v := range intKeyUsageSlice {
 		extKeyUsage = append(extKeyUsage, x509.ExtKeyUsage(v))
 	}
 	return extKeyUsage
 }
 
-func exportPem(filename string, data []byte) {
+func exportPem(filename string, data []byte) (string, error) {
 	outputPath, err := writer.WriteFile(filename, data)
 	if err != nil {
-		log.Fatalf("rootCA.WithClientCert: %s", err)
+		return "", fmt.Errorf("rootCA.WithClientCert: %s", err)
 	}
-	log.Printf("file created successfully: %s\n", outputPath)
+	return outputPath, nil
 }
 
 func init() {
-	intEnvConfig(false)
+	envFile := ""
+	if os.Getenv("ENV") != "prod" {
+		envFile = "./.env"
+	}
+
+	intEnvConfig(envFile)
 	cobra.OnInitialize(initConfig)
 }
 

cmd/main_test.go

@@ -1,7 +1,62 @@
 package cmd
 
-import "testing"
+import (
+	"crypto/x509"
+	"log"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gitlab.com/urkob/go-cert-gen/internal/io"
+)
 
 func TestExecute(t *testing.T) {
 	Execute()
 }
+
+func Test_getExtKeyUsage(t *testing.T) {
+	intKeyUsageSlice := make([]int, 0, 1)
+	intKeyUsageSlice = append(intKeyUsageSlice, int(x509.ExtKeyUsageClientAuth))
+
+	keyUsage := getExtKeyUsage(intKeyUsageSlice)
+	assert.Len(t, keyUsage, len(intKeyUsageSlice))
+	assert.Equal(t, keyUsage[0], x509.ExtKeyUsageClientAuth)
+
+	intKeyUsageSlice = make([]int, 0)
+	keyUsage = getExtKeyUsage(intKeyUsageSlice)
+	assert.Len(t, keyUsage, 0)
+
+	keyUsage = getExtKeyUsage(nil)
+	assert.Len(t, keyUsage, 0)
+}
+
+var testFile = "test-file.txt"
+
+func init() {
+	wd, err := os.Getwd()
+	if err != nil {
+		log.Fatalf("os.Getwd: %s\n", err)
+	}
+	writer = io.NewWriter(wd)
+}
+
+func Test_exportPem(t *testing.T) {
+	defer func() {
+		os.Remove(testFile)
+		err := os.Remove(testFile)
+		require.NoError(t, err)
+	}()
+
+	data := []byte("test data")
+	outputPath, err := exportPem(testFile, data)
+	require.NoError(t, err)
+	require.NotEmpty(t, outputPath)
+}
+
+func Test_exportPemError(t *testing.T) {
+	data := []byte("test data")
+	outputPath, err := exportPem("", data)
+	require.Error(t, err)
+	require.Empty(t, outputPath)
+}

go.mod

@@ -7,15 +7,18 @@ require (
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/spf13/cobra v1.6.1
 	github.com/spf13/viper v1.15.0
+	github.com/stretchr/testify v1.8.1
 )
 
 require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.0.6 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/spf13/afero v1.9.3 // indirect
 	github.com/spf13/cast v1.5.0 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect

internal/cert/client_cert.go

@@ -0,0 +1,80 @@
+package cert
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"time"
+
+	"gitlab.com/urkob/go-cert-gen/pkg/client"
+)
+
+type clientCert struct {
+	certPEM []byte
+	keyPEM  []byte
+}
+
+func (c *clientCert) Key() []byte {
+	return c.keyPEM
+}
+
+func (c *clientCert) PEM() []byte {
+	return c.certPEM
+}
+
+func newClientCert(config *client.ClientCertConfig, rootCA *x509.Certificate, rootKeyPEM []byte) ([]byte, []byte, error) {
+	template := &x509.Certificate{
+		SerialNumber: config.Serial,
+		Subject: pkix.Name{
+			Organization:  []string{config.Subject.Organization},
+			Country:       []string{config.Subject.Country},
+			Province:      []string{config.Subject.Province},
+			Locality:      []string{config.Subject.Locality},
+			StreetAddress: []string{config.Subject.StreetAddress},
+			PostalCode:    []string{config.Subject.PostalCode},
+		},
+		NotBefore:    time.Now(),
+		NotAfter:     time.Now().Add(config.Duration),
+		SubjectKeyId: config.SubjectKeyId,
+		ExtKeyUsage:  config.ExtKeyUsage,
+		KeyUsage:     config.KeyUsage,
+	}
+
+	block, _ := pem.Decode(rootKeyPEM)
+	if block == nil {
+		return nil, nil, errors.New("pem.Decode")
+	}
+
+	caPrivKey, err := x509.ParsePKCS8PrivateKey(block.Bytes)
+	if err != nil {
+		return nil, nil, fmt.Errorf("x509.ParsePKCS8PrivateKey: %s", err)
+	}
+
+	priv, err := newPrivateKey()
+	if err != nil {
+		return nil, nil, fmt.Errorf("newPrivateKey: %s", err)
+	}
+
+	der, err := x509.CreateCertificate(rand.Reader, template, rootCA, &priv.PublicKey, caPrivKey)
+	if err != nil {
+		return nil, nil, fmt.Errorf("x509.CreateCertificate: %s", err)
+	}
+
+	out := &bytes.Buffer{}
+	err = pem.Encode(out, &pem.Block{Type: CERTIFICATE, Bytes: der})
+	if err != nil {
+		return nil, nil, fmt.Errorf("pem.Encode: %s", err)
+	}
+
+	certPEM := out.Bytes()
+	keyPEM, err := encodePrivateKey(priv)
+	if err != nil {
+		return nil, nil, fmt.Errorf("encodePrivateKey: %s", err)
+	}
+
+	return certPEM, keyPEM, nil
+}

internal/cert/client_cert_test.go

@@ -0,0 +1,36 @@
+package cert
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_newClientCert(t *testing.T) {
+	ca, err := NewRootCA(&rootTestConfig)
+	require.NoError(t, err)
+	require.NotNil(t, ca)
+
+	require.NotNil(t, ca.Key())
+	require.Greater(t, len(ca.Key()), 0)
+
+	require.NotNil(t, ca.PEM())
+	require.Greater(t, len(ca.PEM()), 0)
+
+	x509RootCA, err := parseCertificate(ca.PEM())
+	require.NoError(t, err)
+
+	pem, key, err := newClientCert(&clientTestConfig, x509RootCA, ca.Key())
+	require.NoError(t, err)
+
+	require.NotNil(t, pem)
+	require.Greater(t, len(pem), 0)
+
+	require.NotNil(t, key)
+	require.Greater(t, len(key), 0)
+}
+
+func Test_newClientCertErrr(t *testing.T) {
+	_, _, err := newClientCert(&clientTestConfig, nil, []byte{})
+	require.Error(t, err)
+}

internal/cert/root_ca.go

@@ -8,15 +8,104 @@ import (
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/pem"
+	"errors"
 	"fmt"
-	"log"
 	"time"
 
 	"gitlab.com/urkob/go-cert-gen/pkg/ca"
-
 	"gitlab.com/urkob/go-cert-gen/pkg/client"
 )
 
+const (
+	CERTIFICATE = "CERTIFICATE"
+	PRIVATE_KEY = "PRIVATE KEY"
+)
+
+type rootCA struct {
+	caPEM  []byte
+	keyPEM []byte
+}
+
+func (r *rootCA) Key() []byte {
+	return r.keyPEM
+}
+
+func (r *rootCA) PEM() []byte {
+	return r.caPEM
+}
+
+func (r *rootCA) WithClientCert(config *client.ClientCertConfig) (client.ClientCertIface, error) {
+	x509RootCA, err := parseCertificate(r.caPEM)
+	if err != nil {
+		return nil, fmt.Errorf("parseCertificate: %s", err)
+	}
+
+	clientCertPEM, clientKeyPEM, err := newClientCert(config, x509RootCA, r.keyPEM)
+	if err != nil {
+		return nil, fmt.Errorf("newClientCert: %s", err)
+	}
+
+	return &clientCert{
+		certPEM: clientCertPEM,
+		keyPEM:  clientKeyPEM,
+	}, nil
+}
+
+// Create a self-signed certificate.
+func newRootCA(config *ca.CaConfig) ([]byte, []byte, error) {
+	if config == nil {
+		return nil, nil, errors.New("ca.CaConfig config is nil")
+	}
+	priv, err := newPrivateKey()
+	if err != nil {
+		return nil, nil, fmt.Errorf("newPrivateKey: %s", err)
+	}
+
+	template := x509.Certificate{
+		SerialNumber: config.SerialNumber,
+		Subject: pkix.Name{
+			Organization: []string{config.Subject.Organization},
+			CommonName:   config.Subject.CommonName,
+		},
+		NotBefore:             time.Now().Add(-time.Minute),
+		NotAfter:              time.Now().Add(config.Duration),
+		IsCA:                  true,
+		KeyUsage:              config.KeyUsage,
+		ExtKeyUsage:           config.ExtKeyUsage,
+		BasicConstraintsValid: true,
+	}
+	der, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
+	if err != nil {
+		return nil, nil, fmt.Errorf("x509.CreateCertificate: %s", err)
+	}
+
+	out := &bytes.Buffer{}
+	err = pem.Encode(out, &pem.Block{Type: CERTIFICATE, Bytes: der})
+	if err != nil {
+		return nil, nil, fmt.Errorf("pem.Encode: %s", err)
+	}
+
+	caPEM := out.Bytes()
+	keyPEM, err := encodePrivateKey(priv)
+	if err != nil {
+		return nil, nil, fmt.Errorf("encodePrivateKey: %s", err)
+	}
+
+	return caPEM, keyPEM, nil
+}
+
+func NewRootCA(config *ca.CaConfig) (ca.RootCACertificateIface, error) {
+	caPEM, keyPEM, err := newRootCA(config)
+	if err != nil {
+		return nil, fmt.Errorf("newRootCA: %s", err)
+	}
+
+	return &rootCA{
+		caPEM:  caPEM,
+		keyPEM: keyPEM,
+	}, nil
+}
+
 // Creates a new 512bit private key.
 func newPrivateKey() (*ecdsa.PrivateKey, error) {
 	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
@@ -45,155 +134,16 @@ func encodePrivateKey(priv *ecdsa.PrivateKey) ([]byte, error) {
 	out := &bytes.Buffer{}
 	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
 	if err != nil {
-		return nil, fmt.Errorf("marshal: %s", err)
+		return nil, fmt.Errorf("x509.MarshalPKCS8PrivateKey: %s", err)
 	}
+
 	err = pem.Encode(out, &pem.Block{
-		Type:  "PRIVATE KEY",
+		Type:  PRIVATE_KEY,
 		Bytes: privBytes,
 	})
-	return out.Bytes(), err
-}
-
-// Create a self-signed certificate.
-func newRootCA(config *ca.CaConfig) ([]byte, []byte, error) {
-	priv, err := newPrivateKey()
-	if err != nil {
-		return nil, nil, fmt.Errorf("newPrivateKey: %s", err)
-	}
-
-	template := x509.Certificate{
-		SerialNumber: config.SerialNumber,
-		Subject: pkix.Name{
-			Organization: []string{config.Subject.Organization},
-			CommonName:   config.Subject.CommonName,
-		},
-		NotBefore:             time.Now().Add(-time.Minute),
-		NotAfter:              time.Now().Add(config.Duration),
-		IsCA:                  true,
-		KeyUsage:              config.KeyUsage,
-		ExtKeyUsage:           config.ExtKeyUsage,
-		BasicConstraintsValid: true,
-	}
-	der, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
-	if err != nil {
-		return nil, nil, fmt.Errorf("x509.CreateCertificate: %s", err)
-	}
-
-	out := &bytes.Buffer{}
-	err = pem.Encode(out, &pem.Block{Type: "CERTIFICATE", Bytes: der})
-	if err != nil {
-		return nil, nil, fmt.Errorf("pem.Encode: %s", err)
-	}
-
-	caPEM := out.Bytes()
-	keyPEM, err := encodePrivateKey(priv)
-	if err != nil {
-		return nil, nil, fmt.Errorf("encodePrivateKey: %s", err)
-	}
-
-	return caPEM, keyPEM, nil
-}
-
-func newClientCert(config *client.ClientCertConfig, rootCA *x509.Certificate, rootKeyPEM []byte) ([]byte, []byte, error) {
-	template := &x509.Certificate{
-		SerialNumber: config.Serial,
-		Subject: pkix.Name{
-			Organization:  []string{config.Subject.Organization},
-			Country:       []string{config.Subject.Country},
-			Province:      []string{config.Subject.Province},
-			Locality:      []string{config.Subject.Locality},
-			StreetAddress: []string{config.Subject.StreetAddress},
-			PostalCode:    []string{config.Subject.PostalCode},
-		},
-		NotBefore:    time.Now(),
-		NotAfter:     time.Now().Add(config.Duration),
-		SubjectKeyId: config.SubjectKeyId,
-		ExtKeyUsage:  config.ExtKeyUsage,
-		KeyUsage:     config.KeyUsage,
-	}
-
-	block, _ := pem.Decode(rootKeyPEM)
-	caPrivKey, err := x509.ParsePKCS8PrivateKey(block.Bytes)
-	if err != nil {
-		log.Fatalf("x509.ParsePKCS8PrivateKey: %s", err)
-	}
-
-	priv, err := newPrivateKey()
-	if err != nil {
-		return nil, nil, fmt.Errorf("newPrivateKey: %s", err)
-	}
-
-	der, err := x509.CreateCertificate(rand.Reader, template, rootCA, &priv.PublicKey, caPrivKey)
-	if err != nil {
-		return nil, nil, fmt.Errorf("x509.CreateCertificate: %s", err)
-	}
-
-	out := &bytes.Buffer{}
-	err = pem.Encode(out, &pem.Block{Type: "CERTIFICATE", Bytes: der})
-	if err != nil {
-		return nil, nil, fmt.Errorf("pem.Encode: %s", err)
-	}
-
-	certPEM := out.Bytes()
-	keyPEM, err := encodePrivateKey(priv)
-	if err != nil {
-		return nil, nil, fmt.Errorf("encodePrivateKey: %s", err)
-	}
-
-	return certPEM, keyPEM, nil
-}
-
-type rootCA struct {
-	caPEM  []byte
-	keyPEM []byte
-}
-
-type clientCert struct {
-	certPEM []byte
-	keyPEM  []byte
-}
-
-func (c *clientCert) Key() []byte {
-	return c.keyPEM
-}
-
-func (c *clientCert) PEM() []byte {
-	return c.certPEM
-}
-
-func (r *rootCA) WithClientCert(config *client.ClientCertConfig) (client.ClientCertIface, error) {
-	x509RootCA, err := parseCertificate(r.caPEM)
-	if err != nil {
-		return nil, fmt.Errorf("parseCertificate: %s", err)
-	}
-
-	clientCertPEM, clientKeyPEM, err := newClientCert(config, x509RootCA, r.keyPEM)
-	if err != nil {
-		return nil, fmt.Errorf("newClientCert: %s", err)
-	}
-
-	return &clientCert{
-		certPEM: clientCertPEM,
-		keyPEM:  clientKeyPEM,
-	}, nil
-}
-
-func (r *rootCA) Key() []byte {
-	return r.keyPEM
-}
-
-func (r *rootCA) PEM() []byte {
-	return r.caPEM
-}
-
-func NewRootCA(config *ca.CaConfig) (ca.RootCACertificateIface, error) {
-	caPEM, keyPEM, err := newRootCA(config)
-	if err != nil {
-		return nil, fmt.Errorf("newRootCA: %s", err)
-	}
-
-	return &rootCA{
-		caPEM:  caPEM,
-		keyPEM: keyPEM,
-	}, nil
+	if err != nil {
+		return nil, err
+	}
+
+	return out.Bytes(), nil
 }

internal/cert/root_ca_test.go

@@ -0,0 +1,143 @@
+package cert
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/x509"
+	"math/big"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"gitlab.com/urkob/go-cert-gen/pkg/ca"
+	"gitlab.com/urkob/go-cert-gen/pkg/client"
+)
+
+const year = time.Hour * 24 * 365
+
+var rootTestConfig = ca.CaConfig{
+	SerialNumber: big.NewInt(12321),
+	Subject: ca.CaSubject{
+		Organization: "test-organization",
+		CommonName:   "test-organization",
+	},
+	KeyUsage: x509.KeyUsageDigitalSignature,
+	ExtKeyUsage: []x509.ExtKeyUsage{
+		x509.ExtKeyUsageServerAuth,
+		x509.ExtKeyUsageClientAuth,
+	},
+	Duration: year,
+}
+
+var clientTestConfig = client.ClientCertConfig{
+	Serial: big.NewInt(12321),
+	Subject: client.Subject{
+		Organization:  rootTestConfig.Subject.Organization,
+		Country:       "REML",
+		Province:      "REML",
+		Locality:      "REML",
+		StreetAddress: "c/o Sovereign 7 rural free delivery",
+		PostalCode:    "[Near 777]",
+	},
+	Duration:     year,
+	SubjectKeyId: []byte{1, 2, 3, 4, 6},
+	ExtKeyUsage: []x509.ExtKeyUsage{
+		x509.ExtKeyUsageServerAuth,
+		x509.ExtKeyUsageClientAuth,
+	},
+	KeyUsage: x509.KeyUsageDigitalSignature,
+}
+
+func Test_newPrivateKey(t *testing.T) {
+	privKey, err := newPrivateKey()
+	require.NoError(t, err)
+
+	require.NotEmpty(t, privKey.PublicKey.Params().Name)
+	require.Equal(t, elliptic.P256().Params().Name, privKey.PublicKey.Params().Name)
+}
+
+func Test_encodePrivateKey(t *testing.T) {
+	privKey, err := newPrivateKey()
+	require.NoError(t, err)
+
+	bytes, err := encodePrivateKey(privKey)
+	require.NoError(t, err)
+
+	require.NotNil(t, bytes)
+	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)
+
+	require.NoError(t, err)
+	require.NotNil(t, caPEM)
+	require.Greater(t, len(caPEM), 0)
+	require.NotNil(t, keyPEM)
+	require.Greater(t, len(keyPEM), 0)
+}
+
+func Test_newRootCAError(t *testing.T) {
+	_, _, err := newRootCA(&ca.CaConfig{})
+
+	require.Error(t, err)
+}
+
+func Test_parseCertificate(t *testing.T) {
+	caPEM, _, err := newRootCA(&rootTestConfig)
+	require.NoError(t, err)
+
+	rootCert, err := parseCertificate(caPEM)
+	require.NoError(t, err)
+	require.NotNil(t, rootCert)
+	require.Equal(t, rootCert.SignatureAlgorithm, x509.ECDSAWithSHA256)
+	require.Equal(t, rootCert.Issuer.Organization, []string{rootTestConfig.Subject.Organization})
+	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)
+	require.NotNil(t, rootCert)
+
+	clientSrv, err := rootCert.WithClientCert(&clientTestConfig)
+	require.NoError(t, err)
+	require.NotNil(t, clientSrv)
+
+	require.NotNil(t, clientSrv.Key())
+	require.Greater(t, len(clientSrv.Key()), 0)
+
+	require.NotNil(t, clientSrv.PEM())
+	require.Greater(t, len(clientSrv.PEM()), 0)
+}
+
+func Test_rootCA_WithClientCertEror(t *testing.T) {
+	rootCert := rootCA{
+		caPEM: nil,
+	}
+
+	_, err := rootCert.WithClientCert(&clientTestConfig)
+	require.Error(t, err)
+}

internal/io/writer.go

@@ -2,6 +2,7 @@ package io
 
 import (
 	"fmt"
+	"log"
 	"os"
 
 	"gitlab.com/urkob/go-cert-gen/pkg/io"
@@ -11,22 +12,33 @@ type writer struct {
 	dirPath string
 }
 
+// WriteFile writes file into `w writer` directory.
+// Returns outputPath and error
 func (w writer) WriteFile(filename string, data []byte) (string, error) {
+	if filename == "" {
+		return "", fmt.Errorf("filename cannot be empty")
+	}
 	if w.dirPath == "" {
 		return "", fmt.Errorf("export directory cannot be empty")
 	}
-
 	if err := os.MkdirAll(w.dirPath, 0o755); err != nil {
 		return "", err
 	}
+
+	log.Println("to write file")
 	outputPath := w.dirPath + "/" + filename
 	if err := os.WriteFile(outputPath, data, 0o600); err != nil {
 		return "", err
 	}
+	log.Println("file written")
 	return outputPath, nil
 }
 
 func NewWriter(dirPath string) io.WriterIface {
+	return newWriter(dirPath)
+}
+
+func newWriter(dirPath string) *writer {
 	return &writer{
 		dirPath: dirPath,
 	}

internal/io/writer_test.go

@@ -0,0 +1,94 @@
+package io
+
+import (
+	"io/fs"
+	"log"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	testWriterPath      = "testPath"
+	testWriterPathError = "test Path, @:ººººº\\/.Ç*⁺´+"
+	testFileContent     = []byte("test data")
+	testFileName        = "test-file.txt"
+	workingDir          = ""
+)
+
+func deleteAllDirs() error {
+	return os.RemoveAll(testWriterPath)
+}
+
+func init() {
+	err := deleteAllDirs()
+	if err != nil {
+		log.Fatalln("deleteAllDirs: ", err)
+	}
+	workingDir, err = os.Getwd()
+	if err != nil {
+		log.Fatalln("os.Getwd: ", err)
+	}
+}
+
+func Test_newWriter(t *testing.T) {
+	w := newWriter(testWriterPath)
+	require.NotNil(t, w)
+}
+
+func TestNewWriter(t *testing.T) {
+	w := NewWriter(testWriterPath)
+	require.NotNil(t, w)
+}
+
+func Test_writer_WriteFile(t *testing.T) {
+	err := deleteAllDirs()
+	require.NoError(t, err)
+
+	defer func(t *testing.T) {
+		err := deleteAllDirs()
+		require.NoError(t, err)
+	}(t)
+
+	w := newWriter(testWriterPath)
+	wgot, err := w.WriteFile(testFileName, testFileContent)
+	require.NoError(t, err)
+
+	btsReaded, err := os.ReadFile(wgot)
+	require.NoError(t, err)
+	require.NotEmpty(t, btsReaded)
+	require.Equal(t, string(btsReaded), string(testFileContent))
+}
+
+func Test_writer_WriteFileError(t *testing.T) {
+	err := deleteAllDirs()
+	require.NoError(t, err)
+
+	defer func(t *testing.T) {
+		err := deleteAllDirs()
+		require.NoError(t, err)
+	}(t)
+
+	w := newWriter("")
+	_, err = w.WriteFile(testFileName, testFileContent)
+	assert.Error(t, err)
+
+	w = newWriter(testWriterPath)
+	_, err = w.WriteFile("", testFileContent)
+	require.Error(t, err)
+
+	err = os.MkdirAll(testWriterPath, fs.ModeDir)
+	require.NoError(t, err, "mkdir should not throw error")
+
+	err = os.MkdirAll(testWriterPath+"/"+testFileName, fs.ModeDir)
+	require.NoError(t, err)
+
+	_, err = w.WriteFile(testFileName, nil)
+	assert.Error(t, err)
+
+	w = newWriter(testWriterPathError)
+	_, err = w.WriteFile(testFileName, testFileContent)
+	require.Error(t, err)
+}

pkg/client/client.go

@@ -29,26 +29,10 @@ type Subject struct {
 	PostalCode    string
 }
 
+/*
 var (
 	subjectKeyId = []byte{1, 2, 3, 4, 6}
 	extKeyUsage  = []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth}
 	keyUsage     = x509.KeyUsageDigitalSignature
 )
-
-func NewDefaultConfig() *ClientCertConfig {
-	return &ClientCertConfig{
-		Serial: big.NewInt(12321),
-		Subject: Subject{
-			Organization:  "",
-			Country:       "",
-			Province:      "",
-			Locality:      "",
-			StreetAddress: "",
-			PostalCode:    "",
-		},
-		Duration:     time.Duration(time.Hour * 24 * 365),
-		SubjectKeyId: subjectKeyId,
-		ExtKeyUsage:  extKeyUsage,
-		KeyUsage:     keyUsage,
-	}
-}
+*/

pkg/io/writer.go

@@ -1,5 +1,7 @@
 package io
 
 type WriterIface interface {
+	// WriteFile writes file into `w writer` directory.
+	// Returns outputPath and error
 	WriteFile(filename string, data []byte) (string, error)
 }