DevOps: 行为驱动开发 BDD

0500

您将收获

  • 什么是行为驱动型开发？
  • 行为驱动型开发如何提高客户期望值？
  • 如何测试验收标准（Acceptance Criteria），从而确定 “完成 “的定义

目标是什么？

image.png

“If it’s worth building, it’s worth testing. If it’s not worth testing, why are you wasting your time working on it?”

软件测试等级

  1. 验收测试：是否符合业务标准
  2. 系统测试：系统是否符合要求
  3. 集成测试：暴露集成单元之间交互中的故障
  4. 单元测试：目的是验证软件的每个单元是否按设计运行

image.png

行为驱动开发 BDD 与 测试驱动开发TDD 的区别

BDD：

  • 从外到内描述系统的行为
  • 用于集成/验收测试

TDD：

  • 从内到外测试系统的功能
  • 用于单元测试

image.png

“BDD is building the right thing, and TDD is building the thing right.”

BDD策略

  1. 将“五个为什么”原则应用于每个提出的User Story，以便其目的与业务成果明确相关
  2. “从外到内”思考，换句话说，仅实施那些对这些业务成果最直接贡献的行为，以最大限度地减少浪费
  3. 用领域专家、测试人员和开发人员可直接使用的单一符号描述行为，以改善沟通
  4. 将这些技术一直应用到软件的最低抽象层次，特别注意行为的分布，以便保持低成本的进化

五个“为什么”原则

  • Q. “Why did the system fail in production?”
    A. “we found an error condition that wasn’t caught”
  • Q. “Why didn’t we catch this condition?”
    A. “Because we didn’t write a test case for it”
  • Q. “Why didn’t we write a test case”
    A. “Because the developer wasn’t trained in TDD”
  • Q. “Why wasn’t the developer trained in TDD?
    A. “Because we cut the training budget”

BDD 工具?

我们将使用：behave
image.png

BDD 工作流

  1. 首先，开发人员、测试人员和业务人员探索问题领域，并协作生成描述他们想要的行为的具体示例
  2. 接下来，团队使用 Behave 来运行这些示例作为自动验收测试
  3. 当团队致力于解决方案时，Behave 会告诉您哪些示例已实施且有效，并警告您哪些示例尚未实施
  4. 在您不知不觉中，您已经拥有一份既包含软件规范又包含软件测试的文档

BDD 模版

  • Given: Given的目的是在用户（或外部系统）开始与系统交互之前（在“When”步骤中）将系统置于已知状态
  • When: 每个步骤都应描述用户（或外部系统）执行的关键操作
  • Then: 用于观察结果。观察结果应与功能描述中的业务价值/收益相关
  • And: 用于连续语。给定这个和那个…… 然后这个和那个…… 等等
  • But: 用于负延续。给定这个但不是那个……然后这个但不是那个……等等

让我们来看一个示例

功能: 退货归入库存
作为店主，为了跟踪库存，我想在退货时将商品添加回库存。

场景一: 退款的商品应该退回库存

  1. Given 鉴于客户之前从我这里购买了一件黑色毛衣，
  2. And 而我有三件黑色毛衣库存。
  3. When 当他退回黑色毛衣要求退款时
  4. Then 我应该有四件黑色毛衣库存

场景二: 更换后的物品应归还库存

  1. Given 鉴于一位顾客之前从我这里购买了一件蓝色衣服
  2. And 我还有两件蓝色衣服库存
  3. And 还有三件黑色衣服库存
  4. When 当他退回蓝色衣服以更换黑色衣服时
  5. Then 我应该有三件蓝色衣服库存和两件黑色衣服库存。

Behave 文件夹结构

image.png

  • web_steps.py Web 交互的通用步骤
  • pet_steps.py 加载数据的具体步骤

steps.py

# steps.py
from behave import given, when, then


@given('some known state')
def step_impl(context):
    set_up(some, state)

@when('some action is taken')
def step_impl(context):
    perform(some, action)

@given('some other known state')
def step_impl(context):
    set_up(other, state)

@then('some outcome is observed')
def step_impl(context):
    assert(outcome, observed)


@then('some other outcome is observed')
def step_impl(context):
    assert(other_outcome, observed)

对应的feature文件格式如下：

Feature: <description of feature>

As a <stakeholder>
I want <some function>
So that <I can achieve some goal>


Scenario: Test something
    Given some known state
    And some other known state
    When some action is taken
    Then some outcome is observed
    And some other outcome is observed

让我们来看一个例子:
功能: 按类别搜索宠物

作为 宠物店顾客
我需要 能够按类别搜索宠物
这样 我只看到我想购买的宠物类别

Background:
给定以下宠物

名字 类别 可获得
Fido dog True
Kitty cat True
Leo lion False

场景：寻找狗
Given 当我在 “主页 “上,
When 将 “类别 “设为 “狗”,
And 并点击 “搜索 “按钮时,
Then 我应该会看到 “成功 “的信息,
And 并在搜索结果中看到 “Fido”,
But 但我不应该在结果中看到“Kitty”,
And 我不应该在结果中看到 “Leo”这个名字

第一步：加载数据

@given('the following pets')
def step_impl(context):
    """ Load the database with new pets """
    for row in context.table:
        payload = {
            "name": row['name'],
            "category": row['category'],
            "available": row['available'] in ['True', 'true', '1']
            }
        context.resp = requests.post(
        f"{context.base_url}/pets",
        json=payload
        )
        assert context.resp.status_code is 201

第二步: 设置 Env 配置

  • before_all(context)
    after_all(context)

    • 这些在所有features之前和之后运行

  • before_feature(context, feature)
    after_feature(context, feature)

    • 这些在每个feature之前和之后运行

  • before_scenario（上下文，场景）
    after_scenario（上下文，场景）

    • 这些在每个场景运行之前和之后运行

  • before_step(context, step)
    after_step(context, step)

    • 它们在每个步骤之前和之后运行。传入的step是Step的一个实例

  • before_tag(context, tag)
    after_tag(context, tag)

    • 它们在用给定名称标记的部分之前和之后运行
    • 每遇到一个标签，就会按照它们在feature file中出现的顺序调用它们

示例：environment.py

from os import getenv
from selenium import webdriver


WAIT_SECONDS = int(getenv('WAIT_SECONDS', '60'))
BASE_URL = getenv('BASE_URL', 'http://localhost:8080')


def before_all(context):
    """ Executed once before all tests """
    options = webdriver.ChromeOptions() # webdriver.FirefoxOptions()
    options.add_argument("--headless")
    options.add_argument("--no-sandbox") # Bypass OS security model
    context.driver = webdriver.Chrome(options=options)
    context.wait_seconds = WAIT_SECONDS
    context.driver.implicitly_wait(context.wait_seconds) # seconds
    context.base_url = BASE_URL


def after_all(context):
    """ Executed after all tests """
    context.driver.quit()

environment.py文件用于设置Behave测试的环境和配置。它使用Selenium库创建自动化浏览器测试的Web Driver，支持使用Chrome或Firefox进行测试。在测试开始前，会根据环境变量配置Web Driver,在测试结束后关闭浏览器释放资源。通过使用无头(headless)浏览器，测试可以在后台运行，无需显示浏览器窗口。

context是Behave测试上下文对象，用于在步骤之间共享数据；Selenium是一个广泛使用的自动化测试工具，它提供了一组API（Application Programming Interface）用于操作和控制Web浏览器。

动手实践

所需工具

  1. 运行 macOS、Linux 或 Windows 的计算机
  2. Visual Studio Code
  3. 通过 Internet 访问克隆的 GitHub 仓库
  4. GitHub 帐户

步骤

  1. 克隆仓库 https://github.com/nyu-devops/lab-flask-bdd
  2. 在容器中重新打开项目 (请确保Docker已打开）
  3. 终端运行 honcho start
  4. 启动一个新终端
  5. 在新终端中运行behave

image.png测试通过!

让我们来看看主要代码

结构

image.png

pets.feature

Feature: The pet store service back-end
    As a Pet Store Owner
    I need a RESTful catalog service
    So that I can keep track of all my pets

Background:
    Given the following pets
        | name       | category | available | gender  | birthday   |
        | fido       | dog      | True      | MALE    | 2019-11-18 |
        | kitty      | cat      | True      | FEMALE  | 2020-08-13 |
        | leo        | lion     | False     | MALE    | 2021-04-01 |
        | sammy      | snake    | True      | UNKNOWN | 2018-06-04 |

Scenario: The server is running
    When I visit the "Home Page"
    Then I should see "Pet Demo RESTful Service" in the title
    And I should not see "404 Not Found"

Scenario: Create a Pet
    When I visit the "Home Page"
    And I set the "Name" to "Happy"
    And I set the "Category" to "Hippo"
    And I select "False" in the "Available" dropdown
    And I select "Male" in the "Gender" dropdown
    And I set the "Birthday" to "06-16-2022"
    And I press the "Create" button
    Then I should see the message "Success"
    When I copy the "Id" field
    And I press the "Clear" button
    Then the "Id" field should be empty
    And the "Name" field should be empty
    And the "Category" field should be empty
    When I paste the "Id" field
    And I press the "Retrieve" button
    Then I should see the message "Success"
    And I should see "Happy" in the "Name" field
    And I should see "Hippo" in the "Category" field
    And I should see "False" in the "Available" dropdown
    And I should see "Male" in the "Gender" dropdown
    And I should see "2022-06-16" in the "Birthday" field

Scenario: List all pets
    When I visit the "Home Page"
    And I press the "Search" button
    Then I should see the message "Success"
    And I should see "fido" in the results
    And I should see "kitty" in the results
    And I should not see "leo" in the results

Scenario: Search for dogs
    When I visit the "Home Page"
    And I set the "Category" to "dog"
    And I press the "Search" button
    Then I should see the message "Success"
    And I should see "fido" in the results
    And I should not see "kitty" in the results
    And I should not see "leo" in the results

Scenario: Search for available
    When I visit the "Home Page"
    And I select "True" in the "Available" dropdown
    And I press the "Search" button
    Then I should see the message "Success"
    And I should see "fido" in the results
    And I should see "kitty" in the results
    And I should see "sammy" in the results
    And I should not see "leo" in the results

Scenario: Update a Pet
    When I visit the "Home Page"
    And I set the "Name" to "fido"
    And I press the "Search" button
    Then I should see the message "Success"
    And I should see "fido" in the "Name" field
    And I should see "dog" in the "Category" field
    When I change "Name" to "Loki"
    And I press the "Update" button
    Then I should see the message "Success"
    When I copy the "Id" field
    And I press the "Clear" button
    And I paste the "Id" field
    And I press the "Retrieve" button
    Then I should see the message "Success"
    And I should see "Loki" in the "Name" field
    When I press the "Clear" button
    And I press the "Search" button
    Then I should see the message "Success"
    And I should see "Loki" in the results
    And I should not see "fido" in the results

上述feature文件定义了功能、背景、场景和步骤

pet_steps.py

######################################################################
# Copyright 2016, 2023 John J. Rofrano. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
######################################################################


"""
Pet Steps


Steps file for Pet.feature

For information on Waiting until elements are present in the HTML see:
    https://selenium-python.readthedocs.io/waits.html
"""
import requests
from behave import given

# HTTP Return Codes
HTTP_200_OK = 200
HTTP_201_CREATED = 201
HTTP_204_NO_CONTENT = 204

@given('the following pets')
def step_impl(context):
    """ Delete all Pets and load new ones """

    # List all of the pets and delete them one by one
    rest_endpoint = f"{context.base_url}/pets"
    context.resp = requests.get(rest_endpoint)
    assert(context.resp.status_code == HTTP_200_OK)
    for pet in context.resp.json():
        context.resp = requests.delete(f"{rest_endpoint}/{pet['id']}")
        assert(context.resp.status_code == HTTP_204_NO_CONTENT)

    # load the database with new pets
    for row in context.table:
        payload = {
            "name": row['name'],
            "category": row['category'],
            "available": row['available'] in ['True', 'true', '1'],
            "gender": row['gender'],
            "birthday": row['birthday']
        }
        context.resp = requests.post(rest_endpoint, json=payload)
        assert(context.resp.status_code == HTTP_201_CREATED)

上述文件实现了数据的加载

最后我们可以集成到 IBM 云

例如：在 IBM Cloud Pipeline 测试阶段使用它

#!/bin/bash
#Invoke tests here
pip install -qr requirements.txt
echo "**************************************************"
echo " R U N N I N G T H E T E S T S "
echo "**************************************************"
echo "BASE_URL=" $BASE_URL
behave

在这里我们不过多阐述

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