io: move common function and add unit tests for it

pkg/io/fileWriter.go

@@ -0,0 +1,18 @@
+package io
+
+import (
+	"fmt"
+	"os"
+	"path"
+)
+
+// MakeDirForFile creates directory provided in filePath.
+func MakeDirForFile(filePath string, creator string) error {
+	fileName := filePath
+	dir := path.Dir(fileName)
+	err := os.MkdirAll(dir, os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("could not create dir for %s: %v", creator, err)
+	}
+	return nil
+}