Helper for fileExists (#954)

Since we need it at several places (next use case will be step xsDeploy) we should
have a helper for that.

cmd/getConfig.go

@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"github.com/SAP/jenkins-library/pkg/config"
+	"github.com/SAP/jenkins-library/pkg/piperutils"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 )
@@ -54,7 +55,7 @@ func generateConfig() error {
 	}
 
 	var customConfig io.ReadCloser
-	if fileExists(GeneralConfig.CustomConfig) {
+	if piperutils.FileExists(GeneralConfig.CustomConfig) {
 		customConfig, err = configOptions.openFile(GeneralConfig.CustomConfig)
 		if err != nil {
 			return errors.Wrap(err, "config: open failed")
@@ -119,11 +120,3 @@ func defaultsAndFilters(metadata *config.StepData) ([]io.ReadCloser, config.Step
 	//ToDo: retrieve default values from metadata
 	return nil, metadata.GetParameterFilters(), nil
 }
-
-func fileExists(filename string) bool {
-	info, err := os.Stat(filename)
-	if os.IsNotExist(err) {
-		return false
-	}
-	return !info.IsDir()
-}

pkg/piperutils/FileUtils.go

@@ -0,0 +1,14 @@
+package piperutils
+
+import (
+	"os"
+)
+
+// FileExists ...
+func FileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}