{"id":3331,"date":"2020-02-12T11:57:49","date_gmt":"2020-02-12T10:57:49","guid":{"rendered":"https:\/\/www.codemotion.com\/magazine\/?p=3331"},"modified":"2021-12-23T14:10:23","modified_gmt":"2021-12-23T13:10:23","slug":"property-based-testing-2","status":"publish","type":"post","link":"https:\/\/www.codemotion.com\/magazine\/devops\/qa-testing\/property-based-testing-2\/","title":{"rendered":"How to Challenge Your Code with Property-Based Testing \u2013 Part 2"},"content":{"rendered":"\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\t
\n\t\t\t\t\t\t\tTable Of Contents\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t
  1. Introduction to property-based testing<\/a>
  2. Implementing Tests<\/a>
  3. Code as Your Domain Speaks<\/a><\/ol>\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\n\n\n

    Property-based testing suggests a new way to test software, going beyond the example-based approach and stressing your code with random, realistic inputs. Follow this 3-issue mini serie about property<\/span>-based testing and Kenny Baas and Jo\u00e3o Rosa speech at Codemotion Rome 2019.<\/p>\n\n\n\n

    Introduction to property-based testing<\/h2>\n\n\n\n

    In the previous issue of this mini-series about property-based testing<\/a>, we introduced some basic ideas from which property<\/span>-based testing<\/strong> is derived. To sum up, property<\/span>-based testing introduces a degree of fuzziness in test inputs, allowing to spot cases when the system<\/span> under test behaves in unexpected way.<\/p>\n\n\n\n

    Let’s see a trivial but concrete case, showing how to convert check for a simple method<\/span> from unit testing style to a property<\/span>-based approach. Following example will use Java language<\/span> (and JUnit<\/span> testing framework) and QuickCheck<\/span> implementation for Java<\/span>\/Junit<\/span>.<\/p>\n\n\n\n

    Implementing Tests<\/h2>\n\n\n\n

    Our mission is to write and verify a method<\/span> that checks if a discount can be applied. A really naive implementation<\/span> of such method<\/span> and related tests<\/span> can be something like the following one:<\/p>\n\n\n\n