Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like EmailContext often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use EmailContext, and based on these observations, apply Extract Interface, too.
| 1 | <?php | ||
| 23 | class EmailContext extends BehatContext | ||
| 24 | { | ||
| 25 | protected $context; | ||
| 26 | |||
| 27 | protected $mailer; | ||
| 28 | |||
| 29 | /** | ||
| 30 | * Stored to simplify later assertions | ||
| 31 | */ | ||
| 32 | protected $lastMatchedEmail; | ||
| 33 | |||
| 34 | /** | ||
| 35 | * Initializes context. | ||
| 36 | * Every scenario gets it's own context object. | ||
| 37 | * | ||
| 38 | * @param array $parameters context parameters (set them up through behat.yml) | ||
| 39 | */ | ||
| 40 | public function __construct(array $parameters) | ||
| 45 | |||
| 46 | /** | ||
| 47 | * Get Mink session from MinkContext | ||
| 48 | */ | ||
| 49 | public function getSession($name = null) | ||
| 53 | |||
| 54 | /** | ||
| 55 | * @BeforeScenario | ||
| 56 | */ | ||
| 57 | public function before(ScenarioEvent $event) | ||
| 65 | |||
| 66 | /** | ||
| 67 | * @Given /^there should (not |)be an email (to|from) "([^"]*)"$/ | ||
| 68 | */ | ||
| 69 | public function thereIsAnEmailFromTo($negate, $direction, $email) | ||
| 81 | |||
| 82 | /** | ||
| 83 | * @Given /^there should (not |)be an email (to|from) "([^"]*)" titled "([^"]*)"$/ | ||
| 84 | */ | ||
| 85 | public function thereIsAnEmailFromToTitled($negate, $direction, $email, $subject) | ||
| 108 | |||
| 109 | /** | ||
| 110 | * Example: Given the email should contain "Thank you for registering!". | ||
| 111 | * Assumes an email has been identified by a previous step, | ||
| 112 | * e.g. through 'Given there should be an email to "[email protected]"'. | ||
| 113 | * | ||
| 114 | * @Given /^the email should (not |)contain "([^"]*)"$/ | ||
| 115 | */ | ||
| 116 | public function thereTheEmailContains($negate, $content) | ||
| 136 | |||
| 137 | /** | ||
| 138 | * @When /^I click on the "([^"]*)" link in the email (to|from) "([^"]*)"$/ | ||
| 139 | */ | ||
| 140 | View Code Duplication | public function iGoToInTheEmailTo($linkSelector, $direction, $email) | |
| 155 | |||
| 156 | /** | ||
| 157 | * @When /^I click on the "([^"]*)" link in the email (to|from) "([^"]*)" titled "([^"]*)"$/ | ||
| 158 | */ | ||
| 159 | View Code Duplication | public function iGoToInTheEmailToTitled($linkSelector, $direction, $email, $title) | |
| 173 | |||
| 174 | /** | ||
| 175 | * Assumes an email has been identified by a previous step, | ||
| 176 | * e.g. through 'Given there should be an email to "[email protected]"'. | ||
| 177 | * | ||
| 178 | * @When /^I click on the "([^"]*)" link in the email"$/ | ||
| 179 | */ | ||
| 180 | public function iGoToInTheEmail($linkSelector) | ||
| 195 | |||
| 196 | /** | ||
| 197 | * @Given /^I clear all emails$/ | ||
| 198 | */ | ||
| 199 | public function iClearAllEmails() | ||
| 204 | |||
| 205 | /** | ||
| 206 | * Example: Then the email should contain the following data: | ||
| 207 | * | row1 | | ||
| 208 | * | row2 | | ||
| 209 | * Assumes an email has been identified by a previous step. | ||
| 210 | * @Then /^the email should (not |)contain the following data:$/ | ||
| 211 | */ | ||
| 212 | 	public function theEmailContainFollowingData($negate, TableNode $table) { | ||
| 239 | |||
| 240 | /** | ||
| 241 | * @Then /^there should (not |)be an email titled "([^"]*)"$/ | ||
| 242 | */ | ||
| 243 | public function thereIsAnEmailTitled($negate, $subject) | ||
| 257 | |||
| 258 | /** | ||
| 259 | * @Then /^the email should (not |)be sent from "([^"]*)"$/ | ||
| 260 | */ | ||
| 261 | View Code Duplication | public function theEmailSentFrom($negate, $from) | |
| 274 | |||
| 275 | /** | ||
| 276 | * @Then /^the email should (not |)be sent to "([^"]*)"$/ | ||
| 277 | */ | ||
| 278 | View Code Duplication | public function theEmailSentTo($negate, $to) | |
| 291 | } | ||
| 292 | 
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different implementation of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the interface: