Pytest的setup和teardown

pytest實際上是python自帶測試框架unittest的擴展，那麼pytest是如何實現unittest中的setup和teardown的呢？

pytest初始化的類別和作用域

• 模塊級別（Module level setup/teardown）：作用於一個模塊內的所有class和def，對於所有class和def，setup和teardown只執行一次

def setup_module(module):
""" setup any state specific to the execution of the given module."""

def teardown_module(module):
""" teardown any state that was previously setup with a setup_module method."""

• 類級別（Class level setup/teardown）：作用於一個class內中的所有test,所有用例只執行一次setup，當所有用例執行完成後，纔會執行teardown

@classmethod
def setup_class(cls):
""" setup any state specific to the execution of the given class (which usually contains tests). """

@classmethod
def teardown_class(cls):
 """ teardown any state that was previously setup with a call to setup_class. """

• 方法和函數級別（Method and function level setup/teardown）：作用於單個測試用例，若用例沒有執行（如被skip了）或失敗了，則不會執行teardown

def setup_method(self, method):
""" setup any state tied to the execution of the given method in a
class. setup_method is invoked for every test method of a class.
"""

def teardown_method(self, method):
""" teardown any state that was previously setup with a setup_method call.
"""

若用例直接寫在模塊中，而不是在類中，則用：

def setup_function(function):
""" setup any state tied to the execution of the given function.
Invoked for every test function in the module.
"""

def teardown_function(function):
""" teardown any state that was previously setup with a setup_function call.
"""

• pytest.fixture()裝飾函數，結合yield實現初始化和teardown
  舉個例子(pytest）文檔中的：

import smtplib
import pytest
@pytest.fixture(scope="module")
def smtp():
    smtp = smtplib.SMTP("smtp.gmail.com", 587, timeout=5)
    yield smtp # provide the fixture value
    print("teardown smtp")
    smtp.close()

運行結果：

$ pytest -s -q --tb=no
FFteardown smtp
2 failed in 0.12 seconds

pytest用例初始化操作的示例

爲了體現初始化和環境恢復，本節演示採用郵件發送的腳本，可查看郵件發送的腳本：python發送郵件腳本或者參考文章：SMTP發送郵件。

1、setup_method(self, method)

• 在test_method.py中構建了3個測試用例，每個用例在執行前後都會執行setup_method/teardown_method連接smtp和斷開smtp。

import smtplib
from email.mime.text import MIMEText
from email.header import Header
from email.mime.multipart import MIMEMultipart

import pytest

class TestSmtp():
    # 發件人和收件人,換成你自己的發件人、收件人qq號
    sender = "[email protected]"
    receivers = "[email protected]"

    # 郵箱服務器
    smtpserver = "smtp.qq.com"
    smtpport = 465

    # 連接郵箱服務器，qq郵箱和密碼,換成自己的
    username = "[email protected]"
    password = "qq mail's password"
    smtp = smtplib.SMTP_SSL()

    def setup_method(self, method):
        self.smtp.connect(self.smtpserver, self.smtpport)
        self.smtp.login(self.username, self.password)
        print("成功登錄")

    def teardown_method(self, method):
        self.smtp.quit()
        print("斷開連接")

    def test_send_text(self):
        # 郵件發送、接收人員，郵件標題、正文
        msg = MIMEText("微信公衆號號：開源優測", "plain", "utf-8")
        msg["From"] = self.sender
        msg["To"] = self.receivers
        msg["Subject"] = Header("開源優測_DeepTest_from_chenlele_text", "utf-8")

        # 發送郵件
        self.smtp.sendmail(self.sender, self.receivers, msg.as_string())

    def test_send_html(self):
        msg = MIMEText("<p>微信公衆號號：開源優測</p><a href='http://www.testingunion.com'>開源優測社區</a>>", 
        "html", 
        "utf-8")
        msg["From"] = self.sender
        msg["To"] = self.receivers
        msg["Subject"] = Header("開源優測_DeepTest_from_chenlele_html", "utf-8")

        # 發送郵件
        self.smtp.sendmail(self.sender, self.receivers, msg.as_string())

    def test_send_attchment(self):
        # 郵件格式說明、發送、接收人員信息、郵件標題
        msg = MIMEMultipart()
        msg["From"] = self.sender
        msg["To"] = self.receivers
        msg["Subject"] = Header("開源優測_DeepTest_from_chenlele", "utf-8")

        # 構建帶附件的郵件正文
        msg.attach(MIMEText("微信公衆號：開源優測", "plain", "utf-8")) 
    
        # 構造附件,多個附件同理
        attach1 = MIMEText(open("judge_leap.json", 'rb').read(), "base64", "utf-8")
        attach1["Content-Type"] = "application/octet-stream"

        # 這裏filename隨意寫，將會在郵件中顯示
        attach1["Content-Disposition"] = "attrachment;filename=code.py"
    
        # 關聯附件到正文
        msg.attach(attach1)
        # 發送郵件
        self.smtp.sendmail(self.sender, self.receivers, msg.as_string())

查看結果，採用pytest -s -q 運行，-s 可以查看打印信息，-q減少輸出信息：

2、setup_class(cls)

• 作用於class的setup_class/teardown_class，類中所有的用例只會執行一次，如圖所示；
• ps:用例與test_method.py的一致，參考上一串代碼。

3、setup_module(module)

• setup_module/teardown_module在一個模塊內，只會執行一次，作用於模塊內的所有用例
• 示例中構建了2個class和1個def，共4個用例，可以看到，4個用例只執行了一次module

test_module.py

import smtplib
from email.mime.text import MIMEText
from email.header import Header
from email.mime.multipart import MIMEMultipart

import pytest

info = {"sender": "[email protected]", 
        "receivers": "[email protected]",
        "smtpserver": "smtp.qq.com",
        "smtpport": 465,
        "username":"[email protected]",
        "password": "yourpassword",
        "smtp": smtplib.SMTP_SSL()}


def setup_module(module):
    info["smtp"].connect(info["smtpserver"], info["smtpport"])
    info["smtp"].login(info["username"], info["password"])
    print("成功登錄")

def teardown_module(module):
    info["smtp"].quit()
    print("斷開連接")

class TestSendText():
     def test_send_text(self):
        # 郵件發送、接收人員，郵件標題、正文
        msg = MIMEText("微信公衆號號：開源優測", "plain", "utf-8")
        msg["From"] =info["sender"]
        msg["To"] = info["receivers"]
        msg["Subject"] = Header("開源優測_DeepTest_from_chenlele_text", "utf-8")

        # 發送郵件
        info["smtp"].sendmail(info["sender"], info["receivers"], msg.as_string())
    
     def test_send_html(self):
        msg = MIMEText("<p>微信公衆號號：開源優測</p><a href='http://www.testingunion.com'>開源優測社區</a>>", 
        "html", 
        "utf-8")
        msg["From"] = info["sender"]
        msg["To"] = info["receivers"]
        msg["Subject"] = Header("開源優測_DeepTest_from_chenlele_html", "utf-8")

        # 發送郵件
        info["smtp"].sendmail(info["sender"], info["receivers"], msg.as_string())

class TestSendAttach():
    def test_send_attchment(self):
        # 郵件格式說明、發送、接收人員信息、郵件標題
        msg = MIMEMultipart()
        msg["From"] = info["sender"]
        msg["To"] = info["receivers"]
        msg["Subject"] = Header("開源優測_DeepTest_from_chenlele", "utf-8")

        # 構建帶附件的郵件正文
        msg.attach(MIMEText("微信公衆號：開源優測", "plain", "utf-8")) 
    
        # 構造附件,多個附件同理
        attach1 = MIMEText(open("judge_leap.json", 'rb').read(), "base64", "utf-8")
        attach1["Content-Type"] = "application/octet-stream"

        # 這裏filename隨意寫，將會在郵件中顯示
        attach1["Content-Disposition"] = "attrachment;filename=code.py"
    
        # 關聯附件到正文
        msg.attach(attach1)

        # 發送郵件
        info["smtp"].sendmail(info["sender"], info["receivers"], msg.as_string())

def test_send_text_out():
    # 郵件發送、接收人員，郵件標題、正文
    msg = MIMEText("微信公衆號號：開源優測", "plain", "utf-8")
    msg["From"] =info["sender"]
    msg["To"] = info["receivers"]
    msg["Subject"] = Header("class外的用例執行", "utf-8")

    # 發送郵件
    info["smtp"].sendmail(info["sender"], info["receivers"], msg.as_string())

4、pytest.fixture()

• pytest.fixture採用yield實現setup和teardown操作，yield提供的參數爲函數名稱
• 與setup_module類似，pytest.fixture可作用於一個模塊內的所有def和class。區別在於，必須將pytest.fixture()裝飾的函數作爲參數傳遞給用例。
• pytest.fixture()裝飾的函數必須作爲參數傳遞給用例嗎？
  1）、將class中的smtp_ini都刪除，class中的用例執行失敗，def用例執行成功；
  2）、將class中test_send_text的smtp_ini保留，其餘2個刪除，class中的用例都執行成功？這是爲什麼呢？只有1個用力傳入了參數，但所有用例都執行成功了。
  3）、將class和def中的smtp_ini都刪除，用例全部執行失敗。
• ps：用例內容與test_module.py的一致，就不粘代碼了。

總結

4種方式的作用域：

• setup_method:僅作用於class用例集中的用例，置於class內,每個用例都會調用一次
• setup_function:作用於獨立的def用例，不可作用於class內的用例
• setup_class:作用於class用例集中的用例，置於class內，只在class用例執行的開始執行setup_class,結束時執行teardown_class
• setup_module:作用於模塊內的所有用例，置於class外，只在所以用例的開始執行setup_module,結束時執行teardown_module
• pytest.fixture():作用於模塊內的所有用例，但需要傳遞裝飾函數爲參數，可置於class內或class外