"value":"\n <p>If you have multiple implementations of a service, as I <a href=\"/daily\/2023\/08\/23\/dont-use-third-party-services-directly\">mentioned in yesterday's email<\/a>, you need to ensure they all provide the same functionality.<\/p>\n\n<p>You need to be able to run the same tests against each implementation and have them pass.<\/p>\n\n<h2 id=\"how-do-you-do-this%3F\">How do you do this?<\/h2>\n\n<p>In PHP, I use a trait that contains the test methods and then have a test class for each implementation that uses the trait and sets up any test data.<\/p>\n\n<p>Then, each test class will run the methods from the contract test trait and ensure they all provide the same behaviour, regardless of how it does so - whether it communicates with an API, uses an SDK, or returns fake values.<\/p>\n\n<p>If one implementation doesn't return the same result as the others, its test will fail.<\/p>\n\n<p>If you add a new implementation, you create a new test class, use the trait and get the tests to pass.<\/p>\n\n ",
"processed":"\n <p>If you have multiple implementations of a service, as I <a href=\"/daily\/2023\/08\/23\/dont-use-third-party-services-directly\">mentioned in yesterday's email<\/a>, you need to ensure they all provide the same functionality.<\/p>\n\n<p>You need to be able to run the same tests against each implementation and have them pass.<\/p>\n\n<h2 id=\"how-do-you-do-this%3F\">How do you do this?<\/h2>\n\n<p>In PHP, I use a trait that contains the test methods and then have a test class for each implementation that uses the trait and sets up any test data.<\/p>\n\n<p>Then, each test class will run the methods from the contract test trait and ensure they all provide the same behaviour, regardless of how it does so - whether it communicates with an API, uses an SDK, or returns fake values.<\/p>\n\n<p>If one implementation doesn't return the same result as the others, its test will fail.<\/p>\n\n<p>If you add a new implementation, you create a new test class, use the trait and get the tests to pass.<\/p>\n\n ",