Add "-quiet" flag that suppresses output to stdout when set

Fixes #152

cmd/mockery/mockery.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/vektra/mockery/mockery"
 	"runtime/pprof"
+	"syscall"
 )
 
 const regexMetadataChars = "\\.+*?()|[]{}^$"
@@ -27,6 +28,7 @@ type Config struct {
 	fNote      string
 	fProfile   string
 	fVersion   bool
+	quiet 	   bool
 }
 
 func main() {
@@ -37,6 +39,11 @@ func main() {
 	var err error
 	var limitOne bool
 
+	if config.quiet {
+		// if "quiet" flag is set, set os.Stdout to /dev/null to suppress all output to Stdout
+		os.Stdout = os.NewFile(uintptr(syscall.Stdout), os.DevNull)
+	}
+
 	if config.fVersion {
 		fmt.Println(mockery.SemVer)
 		return 
@@ -125,6 +132,7 @@ func parseConfigFromArgs(args []string) Config {
 	flagSet.StringVar(&config.fNote, "note", "", "comment to insert into prologue of each generated file")
 	flagSet.StringVar(&config.fProfile, "cpuprofile", "", "write cpu profile to file")
 	flagSet.BoolVar(&config.fVersion, "version", false, "prints the installed version of mockery")
+	flagSet.BoolVar(&config.quiet, "quiet", false, "suppress output to stdout")
 
 	flagSet.Parse(args[1:])