Incorporate code review feedback

Signed-off-by: Kyle Brennan <[email protected]>

commands/new_function.go

@@ -153,10 +153,10 @@ Download templates:
 
 		fileName = appendFile
 
-		newLineErr := addLastNewline("./" + fileName)
-		if newLineErr != nil {
-			return newLineErr
+		if err := addLastNewline("./" + fileName); err != nil {
+			return err
 		}
+
 		outputMsg = fmt.Sprintf("Stack file updated: %s\n", fileName)
 
 	} else {
@@ -353,31 +353,26 @@ Cannot have duplicate function names in same yaml file`, functionName, appendFil
 }
 
 func addLastNewline(fileName string) error {
-	// open a file as read write
-	file, err := os.OpenFile(fileName, os.O_RDWR, 0600)
-	defer file.Close()
+	bytes, err := os.ReadFile(fileName)
 	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)
+	content := string(bytes)
+	hasLastNewline := strings.HasSuffix(content, "\n")
+	if hasLastNewline {
+		return nil
+	}
 
-	// handle I/O errors
+	file, err := os.OpenFile(fileName, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
 	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)
+		return fmt.Errorf("could not open '%s' to append new lines %s", fileName, err)
 	}
+	defer file.Close()
 
-	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"))
+	if _, err = file.WriteString("\n\n"); err != nil {
+		return fmt.Errorf("could not write to '%s' to append new lines %s", fileName, err)
 	}
+
 	return nil
 }