September 2025
Intermediate to advanced
660 pages
13h 38m
Portuguese (Portugal, Brazil)
Content preview from Introdução ao Python, 3rd Edition
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Capítulo 15. Testes
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O teste de programas pode ser usado para mostrar a presença de bugs, mas nunca para mostrar a ausência deles!
Edsger Dijkstra
Você provavelmente já sabe disso: até mesmo alterações triviais no código podem quebrar seu programa. O Python não tem a verificação de tipo das linguagens estáticas, o que facilita algumas coisas, mas também deixa passar resultados indesejáveis. Testar é essencial.
A maneira mais simples de testar os programas Python é adicionar declarações print(). O Read-Evaluate-Print Loop (REPL) do interpretador interativo Python permite que você edite e teste as alterações rapidamente. No entanto, você não quer declarações print()no código de produção, portanto, precisa se lembrar de removê-las todas.
Pylint
O próximo passo, antes de criar programas de teste, é executar um verificador de código Python. Tradicionalmente, os mais populares são oPylinteo Pyflakes. Você pode instalar um ou ambos usando pip:
$ pip install pylint $ pip install pyflakes
Eles verificam se há erros de código (como fazer referência a uma variável antes de atribuir um valor a ela) e falhas de estilo (o equivalente em código a usar xadrez e listras).O Exemplo 15-1é um programa sem sentido com um bug e um problema de estilo.
Exemplo 15-1. style1.py
a=1b=2(a)(b)(c)
Aqui está a saída inicial do Pylint:
$ pylint style1.py No config ...
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