Fixes #852 optionally add last newline

Author: kylos101

commands/new_function.go

@@ -152,6 +152,11 @@ Download templates:
 		}
 
 		fileName = appendFile
+
+		newLineErr := addLastNewline("./" + fileName)
+		if newLineErr != nil {
+			return newLineErr
+		}
 		outputMsg = fmt.Sprintf("Stack file updated: %s\n", fileName)
 
 	} else {
@@ -346,3 +351,33 @@ Cannot have duplicate function names in same yaml file`, functionName, appendFil
 
 	return nil
 }
+
+func addLastNewline(fileName string) error {
+	// open a file as read write
+	file, err := os.OpenFile(fileName, os.O_RDWR, 0600)
+	defer file.Close()
+	if err != nil {
+		return fmt.Errorf("could not open '%s' to check for new lines %s", fileName, err)
+	}
+
+	// read the last byte of the file (excludes EOF)
+	buffer := make([]byte, 1)
+	fileStats, _ := file.Stat()
+	bytesRead, err := file.ReadAt(buffer, fileStats.Size()-1)
+
+	// handle I/O errors
+	if err != nil {
+		return fmt.Errorf("could not read the last byte of '%s' %s", fileName, err)
+	} else if bytesRead != 1 {
+		return fmt.Errorf("read unexpected # of bytes in '%s'", fileName)
+	}
+
+	hasTrailingNewline := string(buffer) == "\n"
+	if !hasTrailingNewline {
+		// add 2 trailing newlines
+		// this is consistent with append behavior when last byte is already \n
+		file.Seek(0, 2)
+		file.Write([]byte("\n\n"))
+	}
+	return nil
+}