从 Robot Framework 中的某个位置读取文件

Question

如何从 Robot Framework 中的特定字节位置读取文件？

假设我有一个运行了很长时间的进程写入一个长日志文件。我想获取当前文件大小，然后执行一些影响进程行为的操作，然后等待日志文件中出现一些消息。我只想读取从前一个文件大小开始的文件部分。

我是机器人框架的新手。我认为这是一个非常常见的场景，但我还没有找到如何去做。

Answer 1

没有内置关键字可以做到这一点，但是用 python 编写一个非常简单。

例如，使用以下内容创建一个名为“readmore.py”的文件：

from robot.libraries.BuiltIn import BuiltIn

class readmore(object):
      ROBOT_LIBRARY_SCOPE = "TEST SUITE"

      def __init__(self):
            self.fp = {}

      def read_more(self, path):
            # if we don't already know about this file, 
            # set the file pointer to zero
            if path not in self.fp:
                  BuiltIn().log("setting fp to zero", "DEBUG")
                  self.fp[path] = 0

            # open the file, move the pointer to the stored
            # position, read the file, and reset the pointer
            with open(path) as f:
                  BuiltIn().log("seeking to %s" % self.fp[path], "DEBUG")
                  f.seek(self.fp[path])
                  data = f.read()
                  self.fp[path] = f.tell()
                  BuiltIn().log("resetting fp to %s" % self.fp[path], "DEBUG")

                  return data

然后你可以像这样使用它：

*** Settings ***
| Library | readmore.py
| Library | OperatingSystem

*** test cases ***
| Example of "tail-like" reading of a file
| | # read the current contents of the file
| | ${original}= | read more | /tmp/junk.txt

| | # do something to add more data to the file
| | Append to file | /tmp/junk.txt | this is new content\n

| | # read the new data
| | ${new}=  | Read more | /tmp/junk.txt
| | Should be equal | ${new.strip()} | this is new content