python学习重温(2)---自动case生成工具之elementtree

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原创最新推荐文章于 2026-08-17 16:04:26 发布 1k 阅读 AI 写同款· GEO 优化 ›

如何设计自动化测试case？这篇文章我想跟大伙聊聊设计自动化测试case的一些实践和观点。为什么要设计case？无论是功能测试还是自动化测试甚至性能测试，设计测试case都是必须的。当然，不同的测试类型，在设计测试case时候的侧重点和颗粒度是不同的。设计测试case的目的，我个人认为主要有如下几点原因：便于测试活动开展测试工作的本质是尽可能以更高的效率保障交付产出物的质量满足甚至超出预期，这是所有测试工作的最终目标。但在实际的工作实践中，绝大多数的测试工作都是围绕测试case来开展。比如：case评审/冒烟阅读详情

上一篇简单介绍了python的基本语法，主要是从使用C或C++人的观点来说的。这一篇详细说一下，elementtree库的用法。Elenmenttree是python2.5以后加入python标准库的一个用C写的python库。

XML读取

from xml.etree.ElementTree import ElementTree, Element
import sys

def ReadFromXml(path):
    ''''read from xml and prase it
        author:limin 
        path: the file path
        return ElementTree'''
    tree = ElementTree()
    tree.parse(path);
    return tree

仍然以上文的那个XML文件为例子

<?xml version="1.0"?>
<pdml version="0" creator="wireshark/1.20.0.1">
<packet>
  <proto name="geninfo" pos="0" showname="General information" size="98">
    <field name="num" pos="0" show="1246" showname="Number" value="4de" size="98"/>
    <field name="len" pos="0" show="98" showname="Frame Length" value="62" size="98"/>
    <field name="caplen" pos="0" show="98" showname="Captured Length" value="62" size="98"/>
    <field name="timestamp" pos="0" show="Mar  6, 2013 18:28:28.729395000 China Standard Time" showname="Captured Time" value="1362565708.729395000" size="98"/>
  </proto>
  <proto name="frame" showname="Frame 1246: 98 bytes on wire (784 bits), 98 bytes captured (784 bits)" size="98" pos="0">
    <field name="frame.time" showname="Arrival Time: Mar  6, 2013 18:28:28.729395000 China Standard Time" size="0" pos="0" show="Mar  6, 2013 18:28:28.729395000"/>
    <field name="frame.time_epoch" showname="Epoch Time: 1362565708.729395000 seconds" size="0" pos="0" show="1362565708.729395000"/>
    <field name="frame.time_delta" showname="Time delta from previous captured frame: 0.000475000 seconds" size="0" pos="0" show="0.000475000"/>
    <field name="frame.time_delta_displayed" showname="Time delta from previous displayed frame: 0.000000000 seconds" size="0" pos="0" show="0.000000000"/>
    <field name="frame.time_relative" showname="Time since reference or first frame: 93.072253000 seconds" size="0" pos="0" show="93.072253000"/>
    <field name="frame.number" showname="Frame Number: 1246" size="0" pos="0" show="1246"/>
    <field name="frame.len" showname="Frame Length: 98 bytes (784 bits)" size="0" pos="0" show="98"/>
    <field name="frame.cap_len" showname="Capture Length: 98 bytes (784 bits)" size="0" pos="0" show="98"/>
    <field name="frame.marked" showname="Frame is marked: False" size="0" pos="0" show="0"/>
    <field name="frame.ignored" showname="Frame is ignored: False" size="0" pos="0" show="0"/>
    <field name="frame.protocols" showname="Protocols in frame: eth:ip:udp:mmtss:sicap" size="0" pos="0" show="eth:ip:udp:mmtss:sicap"/>
    <field name="frame.coloring_rule.name" showname="Coloring Rule Name: SICAP" size="0" pos="0" show="SICAP"/>
    <field name="frame.coloring_rule.string" showname="Coloring Rule String: sicap" size="0" pos="0" show="sicap"/>
  </proto>
  <proto name="eth" showname="Ethernet II, Src: 192.168.254.1 (00:0f:bb:69:93:ee), Dst: DCT-INF (00:10:18:cb:b5:fd)" size="14" pos="0">
    <field name="eth.dst" showname="Destination: DCT-INF (00:10:18:cb:b5:fd)" size="6" pos="0" show="00:10:18:cb:b5:fd" value="001018cbb5fd">
      <field name="eth.addr" showname="Address: DCT-INF (00:10:18:cb:b5:fd)" size="6" pos="0" show="00:10:18:cb:b5:fd" value="001018cbb5fd"/>
      <field name="eth.ig" showname=".... ...0 .... .... .... .... = IG bit: Individual address (unicast)" size="3" pos="0" show="0" value="0" unmaskedvalue="001018"/>
      <field name="eth.lg" showname=".... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)" size="3" pos="0" show="0" value="0" unmaskedvalue="001018"/>
    </field>
    <field name="eth.src" showname="Source: 192.168.254.1 (00:0f:bb:69:93:ee)" size="6" pos="6" show="00:0f:bb:69:93:ee" value="000fbb6993ee">
      <field name="eth.addr" showname="Address: 192.168.254.1 (00:0f:bb:69:93:ee)" size="6" pos="6" show="00:0f:bb:69:93:ee" value="000fbb6993ee"/>
      <field name="eth.ig" showname=".... ...0 .... .... .... .... = IG bit: Individual address (unicast)" size="3" pos="6" show="0" value="0" unmaskedvalue="000fbb"/>
      <field name="eth.lg" showname=".... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)" size="3" pos="6" show="0" value="0" unmaskedvalue="000fbb"/>
    </field>
    <field name="eth.type" showname="Type: IP (0x0800)" size="2" pos="12" show="0x0800" value="0800"/>
  </proto>
  <proto name="ip" showname="Internet Protocol, Src: 192.168.254.68 (192.168.254.68), Dst: DCT-INF (192.168.254.2)" size="20" pos="14">
    <field name="ip.version" showname="Version: 4" size="1" pos="14" show="4" value="45"/>
    <field name="ip.hdr_len" showname="Header length: 20 bytes" size="1" pos="14" show="20" value="45"/>
    <field name="ip.dsfield" showname="Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)" size="1" pos="15" show="0" value="00">
      <field name="ip.dsfield.dscp" showname="0000 00.. = Differentiated Services Codepoint: Default (0x00)" size="1" pos="15" show="0x00" value="0" unmaskedvalue="00"/>
      <field name="ip.dsfield.ect" showname=".... ..0. = ECN-Capable Transport (ECT): 0" size="1" pos="15" show="0" value="0" unmaskedvalue="00"/>
      <field name="ip.dsfield.ce" showname=".... ...0 = ECN-CE: 0" size="1" pos="15" show="0" value="0" unmaskedvalue="00"/>
    </field>
    <field name="ip.len" showname="Total Length: 84" size="2" pos="16" show="84" value="0054"/>
    <field name="ip.id" showname="Identification: 0xce64 (52836)" size="2" pos="18" show="0xce64" value="ce64"/>
    <field name="ip.flags" showname="Flags: 0x00" size="1" pos="20" show="0x00" value="00">
      <field name="ip.flags.rb" showname="0... .... = Reserved bit: Not set" size="1" pos="20" show="0" value="00"/>
      <field name="ip.flags.df" showname=".0.. .... = Don't fragment: Not set" size="1" pos="20" show="0" value="00"/>
      <field name="ip.flags.mf" showname="..0. .... = More fragments: Not set" size="1" pos="20" show="0" value="00"/>
    </field>
    <field name="ip.frag_offset" showname="Fragment offset: 0" size="2" pos="20" show="0" value="0000"/>
    <field name="ip.ttl" showname="Time to live: 254" size="1" pos="22" show="254" value="fe"/>
    <field name="ip.proto" showname="Protocol: UDP (17)" size="1" pos="23" show="17" value="11"/>
    <field name="ip.checksum" showname="Header checksum: 0x709b [correct]" size="2" pos="24" show="0x709b" value="709b">
      <field name="ip.checksum_good" showname="Good: True" size="2" pos="24" show="1" value="709b"/>
      <field name="ip.checksum_bad" showname="Bad: False" size="2" pos="24" show="0" value="709b"/>
    </field>
    <field name="ip.src" showname="Source: 192.168.254.68 (192.168.254.68)" size="4" pos="26" show="192.168.254.68" value="c0a8fe44"/>
    <field name="ip.addr" showname="Source or Destination Address: 192.168.254.68 (192.168.254.68)" hide="yes" size="4" pos="26" show="192.168.254.68" value="c0a8fe44"/>
    <field name="ip.src_host" showname="Source Host: 192.168.254.68" hide="yes" size="4" pos="26" show="192.168.254.68" value="c0a8fe44"/>
    <field name="ip.host" showname="Source or Destination Host: 192.168.254.68" hide="yes" size="4" pos="26" show="192.168.254.68" value="c0a8fe44"/>
    <field name="ip.dst" showname="Destination: DCT-INF (192.168.254.2)" size="4" pos="30" show="192.168.254.2" value="c0a8fe02"/>
    <field name="ip.addr" showname="Source or Destination Address: DCT-INF (192.168.254.2)" hide="yes" size="4" pos="30" show="192.168.254.2" value="c0a8fe02"/>
    <field name="ip.dst_host" showname="Destination Host: DCT-INF" hide="yes" size="4" pos="30" show="DCT-INF" value="c0a8fe02"/>
    <field name="ip.host" showname="Source or Destination Host: DCT-INF" hide="yes" size="4" pos="30" show="DCT-INF" value="c0a8fe02"/>
  </proto>
  <proto name="udp" showname="User Datagram Protocol, Src Port: 35429 (35429), Dst Port: rfe (5002)" size="8" pos="34">
    <field name="udp.srcport" showname="Source port: 35429 (35429)" size="2" pos="34" show="35429" value="8a65"/>
    <field name="udp.dstport" showname="Destination port: rfe (5002)" size="2" pos="36" show="5002" value="138a"/>
    <field name="udp.port" showname="Source or Destination Port: 35429" hide="yes" size="2" pos="34" show="35429" value="8a65"/>
    <field name="udp.port" showname="Source or Destination Port: 5002" hide="yes" size="2" pos="36" show="5002" value="138a"/>
    <field name="udp.length" showname="Length: 64" size="2" pos="38" show="64" value="0040"/>
    <field name="udp.checksum_coverage" showname="Checksum coverage: 64" hide="yes" size="0" pos="38" show="64"/>
    <field name="udp.checksum" showname="Checksum: 0xf3f8 [validation disabled]" size="2" pos="40" show="0xf3f8" value="f3f8">
      <field name="udp.checksum_good" showname="Good Checksum: False" size="2" pos="40" show="0" value="f3f8"/>
      <field name="udp.checksum_bad" showname="Bad Checksum: False" size="2" pos="40" show="0" value="f3f8"/>
    </field>
  </proto>

调用读取函数后，可以看到在内存中文件的组织结构式这样的

文件在内存中是一个树结构，最外层是elementtree这个对象的内置方法，文件中的内容

elementtree读取的数据，操作的时候到要先获得root，如这个文件，root就是

<pdml version="0" creator="wireshark/1.20.0.1">

获得root的函数为

root = tree.getroot()

root节点下面，具备的属性有

children：root的子节点

attrib：属性，也就是XML文件中用

version="0" creator="wireshark/1.20.0.1

text：没有用<>包围的部分

展开root中的children节点

就可以看到root的节点，也就是用XML文件中<packet></packet> 包围的部分，同时也可以看到packet节点的子节点proto，也就是XML文件中用<proto></proto>包围的部分。

到这来，基本上已经清楚了。elementtree这个库将XML读入内存用层化的机构连接。

XML文件中数据的读取

如上文所说，我们要读取的就是各个层级节点下的attrib,tag,tail,text这几个参数。

几个读取的方法

直接读取

py2.7支持直接读取的方式，如以下代码

for messagelstParaNode in node:     #1st<field
        if messagelstParaNode.attrib['name'] == 'sicap.header': #sicap header
            SicapHead = parseSiCapHead(messagelstParaNode)
            insertRecSendFieldIntoList(SicapMessageList,SicapHead)
        else:
            if messagelstParaNode.attrib['name'].find('sicap.') == 0: #para field 1st message type
               templist.insert(0,messagelstParaNode.attrib['showname'])
               templist.insert(1,SicapHead['value'])
               SicapMessageList.insert(0,templist)
               for message2stParaNode in messagelstParaNode:             #para field 2st message
                 GetFieldinfo(SicapMessageList,message2stParaNode)
                 for message3stParaNode in message2stParaNode:         #para field 3st message
                   GetFieldinfo(SicapMessageList,message3stParaNode)
                   for message4stParaNode in message3stParaNode:     #para field 4st message
                     GetFieldinfo(SicapMessageList,message4stParaNode)
                     for message5stParaNode in message4stParaNode:     #para field 5st message
                       GetFieldinfo(SicapMessageList,message5stParaNode)
                       for message6stParaNode in message5stParaNode:
                         GetFieldinfo(SicapMessageList,message6stParaNode)

这个代码中，node就是root节点对象，一共解析了6层节点。在相应的节点层次，就可以使用采用如下方法访问各个参数