随机数的应用在上一篇介绍量子态模拟采样的算法中，我们就使用到了随机数，随机数在各种蒙特卡洛方法与数值计算中，扮演着非常重要的角色。
在金融领域，随机数则是在加密算法中扮演重要角色，其风险在于，如果随机数可被预测，那么恶意用户就可以利用这一特点，破解对称加密甚至是非对称加密的算法(非对称加密如RSA算法的私钥的挑选其实也有可能使用到随机数)。
在python代码中，可以通过调用random库或者numpy.random库进行随机数的生成，仅需要通过如下的代码即可实现：import randomrandom_number = random.random() # 产生[0,1)之间的均匀随机数import numpy as nprandom_array = random.randn(10) # 产生10个随机数并存储到np格式的一维数组中这些库所产生的随机数，往往被认为是不安全的随机数，其主要特点是通过随机数生成算法，结合硬件的一些独有编号来产生一系列数串。
但是随机数生成算法一般都是已知的，因此还是有一定的潜在风险。
有一个python库函数叫secrets可以产生”安全随机数”，其特点在于不仅利用了一些硬件系统独有信息，如ip和MAC等，主要还利用了系统熵源来生成随机数，增强了所产生随机数的不可预测性。
关于secrets的使用方法， 可以参考其官方文档。
但是，即使是这里所谓的安全随机数，也并不是真随机数，真随机数的产生不依赖于算法。
量子计算与随机数前面写过一篇博客介绍两比特量子系统的模拟，读者可以从中了解到量子计算的一些基本原理与模拟实现。
而另一篇关于量子线路模拟的博客，则介绍了关于开源量子计算框架ProjectQ的一些基本使用方法，在这篇文章中我们也会使用到。
通过量子硬件，我们可以直接读取一系列的随机串，由于这些随机串是由硬件直接给出来的结果，不是通过算法来生成的，因此是完成不可预测的，被称为”真随机数”。
基于pytest的python单元测试框架在使用python编程实现算法时，需要对算法函数或者类进行功能验证，这就需要写测试用例。
python第三方库pytest提供了非常好的自动化测试的功能，配合html插件和覆盖率测试插件，还可以进行更多的测试以及更好的展示测试的结果。
量子计算产生随机数量子计算是基于量子叠加与量子纠缠两种特性进行计算的方案，其结合量子算法的复杂性优势，在量子处理器上可以实现经典计算机无法在有效时间内完成的任务，一般称之为量子优越性。
量子叠加是对量子比特重要特性的一个总结，如下图所示(图片来自于参考链接1)，区分于经典比特，量子比特不仅可以表示0和1，还可以表示处于0和1之间的状态，比如0.5，0.2243等等。
这些状态我们不能直接读取，在硬件上我们只能够读取到0或者1两种状态，这跟经典比特是一样的。
区别在于，即使我们不改变量子比特的状态，不同的测试却会给出不同的结果，而0.5等中间状态，则表示的是出现0或者1状态分别的概率。
由于量子测量会导致量子态的坍缩，也就是说，每一次测量之后，都需要重新制备量子态。
而制备一个产生随机数的量子态，我们可以用如下所示的H量子门 *** 作来实现。
其具体的矩阵表述可以参考这篇博客，量子计算本质上就是用特殊的硬件方法，快速地实现大规模的矩阵运算，这也是其展现量子优势的来源。
这里我们直接使用开源量子计算框架ProjectQ来实现这个门 *** 作，就省去了自己去模拟实习的繁琐 *** 作：# random_number.pyfrom projectq import MainEnginefrom projectq.ops import H, Measuredef random_number_generator(): eng = MainEngine() qubit = eng.allocate_qubit() H | qubit eng.flush() Measure | qubit random_number = int(qubit) eng.flush(deallocate_qubits=True) return random_numberif __name__ == '__main__': random_number = random_number_generator() print ('Random number generated by quantum simulator is: {}'.format(random_number))这里顺带的介绍下ProjectQ的一些 *** 作实现的方法，在ProjectQ中将众多的量子比特作为寄存器来进行调用，这些寄存器都在给定的engine下赋予了各种 *** 作，如量子门 *** 作、打印线路、编译优化等。
编程框架与实际的量子比特并不在架构上的同一个层次，每次传送指令都是通过eng.flush()打包进行编译优化之后，再传送到后端去逐一执行。
因此如果要测量量子比特(在ProjectQ模拟器中必须只能全部执行测量 *** 作，不能只测量其中的某一个部分)，或者是读取某一个量子态的概率时，都需要先执行eng.flush()才行。
接下来简单看下上述代码的执行效果：[dechin@dechin-manjaro pytest]$ python3 random_number.py Random number generated by quantum simulator is: 1[dechin@dechin-manjaro pytest]$ python3 random_number.py Random number generated by quantum simulator is: 1[dechin@dechin-manjaro pytest]$ python3 random_number.py Random number generated by quantum simulator is: 0[dechin@dechin-manjaro pytest]$ python3 random_number.py Random number generated by quantum simulator is: 0[dechin@dechin-manjaro pytest]$ python3 random_number.py Random number generated by quantum simulator is: 1在这个案例中，每一次都会产生一个新的随机数0或者1，并且在量子比特使用结束之后，通过eng.flush(deallocate_qubits=True)可以初始化该寄存器，所有的振幅和测量结果都会被丢弃。
注意！！！需要注意的是，由于这里我们是使用了模拟器来模拟量子计算机的行为，因此得到的随机数结果还是伪随机数。
只有当这一串代码执行在量子处理器上时，我们才能得到真随机数。
pytest测试安装pytest库首先我们可以通过pip来更新安装pytest：[dechin@dechin-manjaro pytest]$ python3 -m pip install -U pytestCollecting pytest Downloading pytest-6.2.2-py3-none-any.whl (280 kB) |████████████████████████████████| 280 kB 464 kB/s Requirement already satisfied, skipping upgrade: iniconfig in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest) (1.1.1)Requirement already satisfied, skipping upgrade: pluggy<1.0.0a1,>=0.12 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest) (0.13.1)Requirement already satisfied, skipping upgrade: attrs>=19.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest) (20.3.0)Requirement already satisfied, skipping upgrade: toml in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest) (0.10.1)Requirement already satisfied, skipping upgrade: packaging in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest) (20.4)Requirement already satisfied, skipping upgrade: py>=1.8.2 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest) (1.9.0)Requirement already satisfied, skipping upgrade: pyparsing>=2.0.2 in /home/dechin/anaconda3/lib/python3.8/site-packages (from packaging->pytest) (2.4.7)Requirement already satisfied, skipping upgrade: six in /home/dechin/anaconda3/lib/python3.8/site-packages (from packaging->pytest) (1.15.0)Installing collected packages: pytest Attempting uninstall: pytest Found existing installation: pytest 6.2.1 Uninstalling pytest-6.2.1: Successfully uninstalled pytest-6.2.1Successfully installed pytest-6.2.2安装完成后，可以通过如下指令来查看安装的pytest版本：[dechin@dechin-manjaro pytest]$ pytest --versionpytest 6.2.2pytest单元测试用例撰写根据前面一个章节中的random_number.py文件，我们可以对照的写一个简单测试用例：# test_random_number.pyimport pytestfrom random_number import random_number_generator as rngdef test_random_number_generator(): for i in range(10): random_number = rng() assert random_number == 0 or random_number == 1该测试用例的含义为：导入rng函数之后，测试10次该函数的返回值，所返回的值必须是0或者1的随机数，如果输出了这两个数字以外的返回结果，那么说明这个随机数产生器功能上存在问题。
基于pytest的测试代码可以通过如下的指令来运行：[dechin@dechin-20n2s01200 pytest]$ py.test=========================================== test session starts ============================================platform linux -- Python 3.8.5, pytest-6.2.2, py-1.9.0, pluggy-0.13.1rootdir: /home/dechin/projects/2021-python/pytestplugins: cov-2.11.1, metadata-1.11.0, html-3.1.1collected 1 item test_random_number.py . [100%]============================================= warnings summary =============================================../../../anaconda3/lib/python3.8/site-packages/projectq/ops/_gates.py:118 /home/dechin/anaconda3/lib/python3.8/site-packages/projectq/ops/_gates.py:118: PendingDeprecationWarning: the matrix subclass is not the recommended way to represent matrices or deal with linear algebra (see https://docs.scipy.org/doc/numpy/user/numpy-for-matlab-users.html). Please adjust your code to use regular ndarray. return np.matrix([[1, 0], [0, 1j]])../../../anaconda3/lib/python3.8/site-packages/projectq/ops/_gates.py:133 /home/dechin/anaconda3/lib/python3.8/site-packages/projectq/ops/_gates.py:133: PendingDeprecationWarning: the matrix subclass is not the recommended way to represent matrices or deal with linear algebra (see https://docs.scipy.org/doc/numpy/user/numpy-for-matlab-users.html). Please adjust your code to use regular ndarray. return np.matrix([[1, 0], [0, cmath.exp(1j * cmath.pi / 4)]])test_random_number.py: 40 warnings /home/dechin/anaconda3/lib/python3.8/site-packages/projectq/ops/_gates.py:69: PendingDeprecationWarning: the matrix subclass is not the recommended way to represent matrices or deal with linear algebra (see https://docs.scipy.org/doc/numpy/user/numpy-for-matlab-users.html). Please adjust your code to use regular ndarray. return 1. / cmath.sqrt(2.) * np.matrix([[1, 1], [1, -1]])-- Docs: https://docs.pytest.org/en/stable/warnings.html====================================== 1 passed, 42 warnings in 0.50s ======================================从返回的结果来看，出现了1 passed而没有failed，说明所有的测试用例都已经执行成功了，但是这里存在不少的告警warnings信息。
pytest初始化配置文件在上一节的测试结果中，我们发现有非常多的测试告警。
假如我们确认这些告警信息可以忽略，那么我们可以通过在指令中配置忽略告警信息，或者直接使用这里介绍的pytest.ini来忽略相应的告警信息：# pytest.ini[pytest]filterwarnings = ignore::PendingDeprecationWarning在当前目录下的ini配置文件中，我们添加了PendingDeprecationWarning作为忽略项，然后我们再回头看一下上述用例的测试结果：[dechin@dechin-manjaro pytest]$ py.test=========================================== test session starts ============================================platform linux -- Python 3.8.5, pytest-6.2.2, py-1.9.0, pluggy-0.13.1rootdir: /home/dechin/projects/2021-python/pytest, configfile: pytest.iniplugins: cov-2.11.1, metadata-1.11.0, html-3.1.1collected 1 item test_random_number.py . [100%]============================================ 1 passed in 0.50s =============================================这里返回的结果中就没有告警信息了。
pytest生成html格式报告为了更好的展现测试的结果，这里我们需要先安装一个组件pytest-html：[dechin@dechin-manjaro pytest]$ python3 -m pip install pytest-htmlCollecting pytest-html Downloading pytest_html-3.1.1-py3-none-any.whl (14 kB)Collecting pytest-metadata Downloading pytest_metadata-1.11.0-py2.py3-none-any.whl (10 kB)Requirement already satisfied: pytest!=6.0.0,>=5.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest-html) (6.2.1)Requirement already satisfied: attrs>=19.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest!=6.0.0,>=5.0->pytest-html) (20.3.0)Requirement already satisfied: py>=1.8.2 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest!=6.0.0,>=5.0->pytest-html) (1.9.0)Requirement already satisfied: toml in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest!=6.0.0,>=5.0->pytest-html) (0.10.1)Requirement already satisfied: packaging in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest!=6.0.0,>=5.0->pytest-html) (20.4)Requirement already satisfied: pluggy<1.0.0a1,>=0.12 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest!=6.0.0,>=5.0->pytest-html) (0.13.1)Requirement already satisfied: iniconfig in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest!=6.0.0,>=5.0->pytest-html) (1.1.1)Requirement already satisfied: six in /home/dechin/anaconda3/lib/python3.8/site-packages (from packaging->pytest!=6.0.0,>=5.0->pytest-html) (1.15.0)Requirement already satisfied: pyparsing>=2.0.2 in /home/dechin/anaconda3/lib/python3.8/site-packages (from packaging->pytest!=6.0.0,>=5.0->pytest-html) (2.4.7)Installing collected packages: pytest-metadata, pytest-htmlSuccessfully installed pytest-html-3.1.1 pytest-metadata-1.11.0安装成功后，执行如下指令，可以在当前目录下生成一个指定文件名的html文件，如下图所示，就比较全面且美观的展示了测试中的信息：[dechin@dechin-manjaro pytest]$ py.test --html=pytest_report.html=========================================== test session starts ============================================platform linux -- Python 3.8.5, pytest-6.2.2, py-1.9.0, pluggy-0.13.1rootdir: /home/dechin/projects/2021-python/pytest, configfile: pytest.iniplugins: cov-2.11.1, metadata-1.11.0, html-3.1.1collected 1 item test_random_number.py . [100%]--------- generated html file: file:///home/dechin/projects/2021-python/pytest/pytest_report.html ----------============================================ 1 passed in 0.51s =============================================不过在问题数量并不是很多的情况下，直接看命令行输出也是比较方便的。
pytest覆盖率测试在一个python仓库中我们有可能有非常多的函数、类和文件等，为了保障结果的准确性，我们需要能够给出一个可信的覆盖率测试的结论，只有当覆盖率达到100%时，我们才能认为测试工作已经比较全面的考虑。
当然，覆盖率100%的测试，其实并不能保障100%的不出问题，这就是另外的话题了。
首先我们又需要补充安装一个组件pytest-cov：[dechin@dechin-manjaro pytest]$ python3 -m pip install pytest-covCollecting pytest-cov Downloading pytest_cov-2.11.1-py2.py3-none-any.whl (20 kB)Collecting coverage>=5.2.1 Downloading coverage-5.4-cp38-cp38-manylinux2010_x86_64.whl (245 kB) |████████████████████████████████| 245 kB 15 kB/s Requirement already satisfied: pytest>=4.6 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest-cov) (6.2.1)Requirement already satisfied: attrs>=19.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest>=4.6->pytest-cov) (20.3.0)Requirement already satisfied: packaging in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest>=4.6->pytest-cov) (20.4)Requirement already satisfied: iniconfig in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest>=4.6->pytest-cov) (1.1.1)Requirement already satisfied: toml in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest>=4.6->pytest-cov) (0.10.1)Requirement already satisfied: py>=1.8.2 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest>=4.6->pytest-cov) (1.9.0)Requirement already satisfied: pluggy<1.0.0a1,>=0.12 in /home/dechin/anaconda3/lib/python3.8/site-packages (from pytest>=4.6->pytest-cov) (0.13.1)Requirement already satisfied: six in /home/dechin/anaconda3/lib/python3.8/site-packages (from packaging->pytest>=4.6->pytest-cov) (1.15.0)Requirement already satisfied: pyparsing>=2.0.2 in /home/dechin/anaconda3/lib/python3.8/site-packages (from packaging->pytest>=4.6->pytest-cov) (2.4.7)Installing collected packages: coverage, pytest-covSuccessfully installed coverage-5.4 pytest-cov-2.11.1然后在当前目录下执行以下指令：[dechin@dechin-manjaro pytest]$ py.test --cov=random_number ./ --cov-report=html=========================================== test session starts ============================================platform linux -- Python 3.8.5, pytest-6.2.1, py-1.9.0, pluggy-0.13.1rootdir: /home/dechin/projects/2021-python/pytest, configfile: pytest.iniplugins: cov-2.11.1, metadata-1.11.0, html-3.1.1collected 1 item test_random_number.py . [100%]----------- coverage: platform linux, python 3.8.5-final-0 -----------Coverage HTML written to dir htmlcov============================================ 1 passed in 0.76s =============================================这里会提示我们去htmlcov目录下找测试报告，我们打开相应的index.html文件，效果如下：这里我们看到random_number.py文件的测试覆盖率为86%，我们可以点开链接查看剩下未覆盖的测试是什么内容：原来是main函数中的几行指令没有被测试到，一般我们在正式仓库中，是需要去掉main函数的，如果不是测试文件的话。
使用flake8进行python编码规范检查首先我们还是使用pip来直接安装flake8组件，其集成了PEP8的python编码规范：[dechin@dechin-manjaro pytest]$ python3 -m pip install -U flake8Requirement already up-to-date: flake8 in /home/dechin/anaconda3/lib/python3.8/site-packages (3.8.4)Requirement already satisfied, skipping upgrade: mccabe<0.7.0,>=0.6.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8) (0.6.1)Requirement already satisfied, skipping upgrade: pyflakes<2.3.0,>=2.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8) (2.2.0)Requirement already satisfied, skipping upgrade: pycodestyle<2.7.0,>=2.6.0a1 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8) (2.6.0)查看安装的flake8版本号：[dechin@dechin-manjaro pytest]$ flake8 --version3.8.4 (mccabe: 0.6.1, pycodestyle: 2.6.0, pyflakes: 2.2.0) CPython 3.8.5 on Linux使用方式较为简单，在当前目录下直接执行flake8即可，检查项会以当前路径为rootdir，递归地进行检索：[dechin@dechin-manjaro pytest]$ flake8./test_random_number.py:2:1: F401 'pytest' imported but unused./test_random_number.py:5:1: E302 expected 2 blank lines, found 1./random_number.py:5:1: E302 expected 2 blank lines, found 1./random_number.py:15:1: E305 expected 2 blank lines after class or function definition, found 1./random_number.py:17:10: E211 whitespace before '('./random_number.py:17:80: E501 line too long (87 > 79 characters)假如我们不想包含测试用例的风格检查，我们可以在命令行中屏蔽相关文件，或者创建配置文件，在配置文件中屏蔽相关文件，这里介绍后者的使用方法：# .flake8[flake8]exclude = ./test*这个配置的意义在于，将当前目录下，所有以test开头的文件，都将会忽略python编码规范的检查，配置文件支持通配符的表达形式。
接下来看下最新的执行结果：[dechin@dechin-manjaro pytest]$ flake8./random_number.py:5:1: E302 expected 2 blank lines, found 1./random_number.py:15:1: E305 expected 2 blank lines after class or function definition, found 1./random_number.py:17:10: E211 whitespace before '('./random_number.py:17:80: E501 line too long (87 > 79 characters)我们发现前面出现的关于测试用例中的编码规范，已经不在这个列表的范围了。
这个列表中的问题我们一般最好是处理下，但是如果遇到一些判断不需要处理的规范，则同样可以在配置文件中添加相应的规范ID，这里仅作示例使用，前面显示的编码规范问题后面都会改。
如下所示就是两个忽略：# .flake8[flake8]exclude = ./test*ignore = E302, E305对应的执行结果如下所示：[dechin@dechin-manjaro pytest]$ flake8./random_number.py:17:10: E211 whitespace before '('./random_number.py:17:80: E501 line too long (87 > 79 characters)我们发现被忽略的问题已经没有显示了。
flake8还有一个特点，是可以配置max-complexity，其采用的基本复杂性计算方法为McCabe度量法，可以参考这篇博客中的介绍内容，这里就不过多的赘述。
为了更加美观简明地看到输出的结果，我们可以补充安装一个组件flake8-html：[dechin@dechin-manjaro pytest]$ python3 -m pip install flake8-htmlCollecting flake8-html Downloading flake8_html-0.4.1-py2.py3-none-any.whl (13 kB)Requirement already satisfied: pygments>=2.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8-html) (2.7.2)Requirement already satisfied: flake8>=3.3.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8-html) (3.8.4)Requirement already satisfied: jinja2>=2.9.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8-html) (2.11.2)Requirement already satisfied: importlib-metadata in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8-html) (2.0.0)Requirement already satisfied: pycodestyle<2.7.0,>=2.6.0a1 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8>=3.3.0->flake8-html) (2.6.0)Requirement already satisfied: mccabe<0.7.0,>=0.6.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8>=3.3.0->flake8-html) (0.6.1)Requirement already satisfied: pyflakes<2.3.0,>=2.2.0 in /home/dechin/anaconda3/lib/python3.8/site-packages (from flake8>=3.3.0->flake8-html) (2.2.0)Requirement already satisfied: MarkupSafe>=0.23 in /home/dechin/anaconda3/lib/python3.8/site-packages (from jinja2>=2.9.0->flake8-html) (1.1.1)Requirement already satisfied: zipp>=0.5 in /home/dechin/anaconda3/lib/python3.8/site-packages (from importlib-metadata->flake8-html) (3.4.0)Installing collected packages: flake8-htmlSuccessfully installed flake8-html-0.4.1使用方法如下：[dechin@dechin-20n2s01200 pytest]$ flake8 --format=html --htmldir=flake-report./random_number.py has issues: medium: 4在当前目录执行后，相关的规范的issue就不会在命令行里面逐一显示，都在flake-report目录下的index.html中可以查看：我们可以点击进入相应文件的issue清单中去查看：可以点击每一个issue，展开内容中包含了issue所对应行的代码内容：经过一番修改之后，我们得到的flake8配置文件和源代码文件如下：# .flake8[flake8]exclude = ./test*ignore = W391# random_number.pyfrom projectq import MainEnginefrom projectq.ops import H, Measuredef random_number_generator(): eng = MainEngine() qubit = eng.allocate_qubit() H | qubit eng.flush() Measure | qubit random_number = int(qubit) eng.flush(deallocate_qubits=True) return random_numberif __name__ == '__main__': random_number = random_number_generator() print('Random number generated by quantum simulator is: {}'.format(random_number))最终我们的目的是使得flake8执行的issue清零：[dechin@dechin-manjaro pytest]$ flake8 --format=html --htmldir=flake-report[dechin@dechin-manjaro pytest]$总结概要本文通过引入一个随机数生成器的案例，介绍了在量子计算中产生真随机数的方案，同时给出了量子计算模拟实现。
借此机会也同时介绍了python的单元测试库pytest的一些常规和扩展使用方法，以及python的编码规范测试库flake8的基本使用方法，希望能够对大家有所启发以及帮助。
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