fix: Set HelmBinary in execer constructor (#928)

This overrides the default helm command, if provided, as soon as possible.
This way it is already used in `visitStates`.


I ran into an issue using `HELM3` and `--helm-binary` together with helm-secrets. 
I previously used tillerless, which i could now remove. This however caused `DecryptSecret` to fail, as it would still use the helm2 binary; because it runs before the first `helm.SetHelmBinary` call.

While helm-secrets is not fully helm3 compatible yet, its uses within helmfile are, and i was able to just install it as a helm3 plugin.

pkg/helmexec/exec.go

@@ -13,10 +13,6 @@ import (
 	"go.uber.org/zap/zapcore"
 )
 
-const (
-	command = "helm"
-)
-
 type decryptedSecret struct {
 	mutex sync.RWMutex
 	bytes []byte
@@ -50,9 +46,9 @@ func NewLogger(writer io.Writer, logLevel string) *zap.SugaredLogger {
 }
 
 // New for running helm commands
-func New(logger *zap.SugaredLogger, kubeContext string, runner Runner) *execer {
+func New(helmBinary string, logger *zap.SugaredLogger, kubeContext string, runner Runner) *execer {
 	return &execer{
-		helmBinary:       command,
+		helmBinary:       helmBinary,
 		logger:           logger,
 		kubeContext:      kubeContext,
 		runner:           runner,

pkg/helmexec/exec_test.go

@@ -24,7 +24,7 @@ func (mock *mockRunner) Execute(cmd string, args []string, env map[string]string
 }
 
 func MockExecer(logger *zap.SugaredLogger, kubeContext string) *execer {
-	execer := New(logger, kubeContext, &mockRunner{})
+	execer := New("helm", logger, kubeContext, &mockRunner{})
 	return execer
 }
 
@@ -33,7 +33,7 @@ func MockExecer(logger *zap.SugaredLogger, kubeContext string) *execer {
 func TestNewHelmExec(t *testing.T) {
 	buffer := bytes.NewBufferString("something")
 	logger := NewLogger(buffer, "debug")
-	helm := New(logger, "dev", &ShellRunner{
+	helm := New("helm", logger, "dev", &ShellRunner{
 		Logger: logger,
 	})
 	if helm.kubeContext != "dev" {
@@ -50,7 +50,7 @@ func TestNewHelmExec(t *testing.T) {
 func Test_SetExtraArgs(t *testing.T) {
 	buffer := bytes.NewBufferString("something")
 	logger := NewLogger(buffer, "debug")
-	helm := New(NewLogger(os.Stdout, "info"), "dev", &ShellRunner{
+	helm := New("helm", NewLogger(os.Stdout, "info"), "dev", &ShellRunner{
 		Logger: logger,
 	})
 	helm.SetExtraArgs()
@@ -70,7 +70,7 @@ func Test_SetExtraArgs(t *testing.T) {
 func Test_SetHelmBinary(t *testing.T) {
 	buffer := bytes.NewBufferString("something")
 	logger := NewLogger(buffer, "debug")
-	helm := New(NewLogger(os.Stdout, "info"), "dev", &ShellRunner{
+	helm := New("helm", NewLogger(os.Stdout, "info"), "dev", &ShellRunner{
 		Logger: logger,
 	})
 	if helm.helmBinary != "helm" {