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:
| 1 | <?php  | 
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| 15 | class ContentContext extends RawDrupalContext { | 
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| 16 | |||
| 17 | /**  | 
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| 18 | * Assert viewing content given its type and title.  | 
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| 19 | *  | 
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| 20 | * @param string $type  | 
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| 21 | * Content type machine name.  | 
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| 22 | * @param string $title  | 
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| 23 | * Content title.  | 
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| 24 | *  | 
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| 25 | * @Given I am visiting the :type content :title  | 
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| 26 | * @Given I visit the :type content :title  | 
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| 27 | */  | 
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| 28 |   public function iAmViewingTheContent($type, $title) { | 
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| 31 | |||
| 32 | /**  | 
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| 33 | * Assert editing content given its type and title.  | 
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| 34 | *  | 
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| 35 | * @param string $type  | 
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| 36 | * Content type machine name.  | 
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| 37 | * @param string $title  | 
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| 38 | * Content title.  | 
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| 39 | *  | 
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| 40 | * @Given I am editing the :type content :title  | 
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| 41 | * @Given I edit the :type content :title  | 
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| 42 | */  | 
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| 43 |   public function iAmEditingTheContent($type, $title) { | 
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| 46 | |||
| 47 | /**  | 
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| 48 | * Assert deleting content given its type and title.  | 
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| 49 | *  | 
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| 50 | * @param string $type  | 
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| 51 | * Content type machine name.  | 
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| 52 | * @param string $title  | 
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| 53 | * Content title.  | 
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| 54 | *  | 
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| 55 | * @Given I am deleting the :type content :title  | 
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| 56 | * @Given I delete the :type content :title  | 
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| 57 | */  | 
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| 58 |   public function iAmDeletingTheContent($type, $title) { | 
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| 61 | |||
| 62 | /**  | 
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| 63 | * Provides a common step definition callback for node pages.  | 
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| 64 | *  | 
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| 65 | * @param string $op  | 
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| 66 | * The operation being performed: 'view', 'edit', 'delete'.  | 
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| 67 | * @param string $type  | 
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| 68 | * The node type either as id or as label.  | 
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| 69 | * @param string $title  | 
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| 70 | * The node title.  | 
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| 71 | */  | 
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| 72 |   protected function visitContentPage($op, $type, $title) { | 
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| 81 | |||
| 82 | /**  | 
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| 83 | * Assert that given user can perform given operation on given content.  | 
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| 84 | *  | 
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| 85 | * @param string $name  | 
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| 86 | * User name.  | 
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| 87 | * @param string $op  | 
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| 88 | * Operation: view, edit or delete.  | 
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| 89 | * @param string $title  | 
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| 90 | * Content title.  | 
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| 91 | *  | 
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| 92 | * @throws \Exception  | 
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| 93 | * If user cannot perform given operation on given content.  | 
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| 94 | *  | 
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| 95 | * @Then :name can :op content :content  | 
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| 96 | * @Then :name can :op :content content  | 
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| 97 | */  | 
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| 98 | View Code Duplication |   public function userCanContent($name, $op, $title) { | 
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| 106 | |||
| 107 | /**  | 
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| 108 | * Assert that given user cannot perform given operation on given content.  | 
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| 109 | *  | 
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| 110 | * @param string $name  | 
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| 111 | * User name.  | 
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| 112 | * @param string $op  | 
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| 113 | * Operation: view, edit or delete.  | 
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| 114 | * @param string $title  | 
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| 115 | * Content title.  | 
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| 116 | *  | 
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| 117 | * @throws \Exception  | 
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| 118 | * If user can perform given operation on given content.  | 
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| 119 | *  | 
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| 120 | * @Then :name can not :op content :content  | 
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| 121 | * @Then :name cannot :op content :content  | 
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| 122 | * @Then :name cannot :op :content content  | 
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| 123 | */  | 
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| 124 | View Code Duplication |   public function userCanNotContent($name, $op, $title) { | 
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| 132 | |||
| 133 | /**  | 
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| 134 | * Assert presence of content edit link given its name and content title.  | 
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| 135 | *  | 
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| 136 | * @param string $link  | 
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| 137 | * Link "name" HTML attribute.  | 
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| 138 | * @param string $title  | 
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| 139 | * Content title.  | 
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| 140 | *  | 
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| 141 | * @throws \Behat\Mink\Exception\ExpectationException  | 
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| 142 | * If no edit link for given content has been found.  | 
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| 143 | *  | 
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| 144 | * @Then I should see the link :link to edit content :content  | 
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| 145 | * @Then I should see a link :link to edit content :content  | 
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| 146 | */  | 
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| 147 |   public function assertContentEditLink($link, $title) { | 
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| 152 | |||
| 153 | /**  | 
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| 154 | * Assert absence of content edit link given its content title.  | 
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| 155 | *  | 
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| 156 | * @param string $title  | 
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| 157 | * Content title.  | 
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| 158 | *  | 
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| 159 | * @throws \Behat\Mink\Exception\ExpectationException  | 
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| 160 | * If edit link for given content has been found.  | 
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| 161 | *  | 
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| 162 | * @Then I should not see a link to edit content :content  | 
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| 163 | * @Then I should not see the link to edit content :content  | 
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| 164 | */  | 
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| 165 |   public function assertNoContentEditLink($title) { | 
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| 170 | |||
| 171 | |||
| 172 | /**  | 
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| 173 | * Create content defined in YAML format.  | 
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| 174 | *  | 
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| 175 | * @param PyStringNode $string  | 
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| 176 | * The text in yaml format that represents the content.  | 
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| 177 | *  | 
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| 178 | * @Given the following content:  | 
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| 179 | */  | 
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| 180 |   public function assertContent(PyStringNode $string) { | 
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| 190 | |||
| 191 | /**  | 
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| 192 | * Assert translation for given content.  | 
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| 193 | *  | 
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| 194 | * @param string $content_type  | 
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| 195 | * The node type for which to add the translation.  | 
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| 196 | * @param string $title  | 
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| 197 | * The title to identify the content by.  | 
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| 198 | * @param PyStringNode $string  | 
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| 199 | * The text in yaml format that represents the translation.  | 
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| 200 | *  | 
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| 201 | * @Given the following translation for :content_type content :title:  | 
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| 202 | */  | 
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| 203 |   public function assertTranslation($content_type, $title, PyStringNode $string) { | 
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| 212 | |||
| 213 | /**  | 
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| 214 | * Get the edit link for a node.  | 
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| 215 | *  | 
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| 216 | * @param string $link  | 
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| 217 | * The link name.  | 
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| 218 | * @param string $title  | 
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| 219 | * The node title.  | 
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| 220 | *  | 
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| 221 | * @return \Behat\Mink\Element\NodeElement|null  | 
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| 222 | * The link if found.  | 
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| 223 | *  | 
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| 224 | * @throws \Exception  | 
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| 225 | */  | 
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| 226 |   protected function getContentEditLink($link, $title) { | 
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| 246 | |||
| 247 | /**  | 
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| 248 | * Get the yaml parser from the behat container.  | 
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| 249 | *  | 
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| 250 | * @return \NuvoleWeb\Drupal\DrupalExtension\Component\PyStringYamlParser  | 
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| 251 | * The parser.  | 
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| 252 | */  | 
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| 253 |   protected function getYamlParser() { | 
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| 256 | |||
| 257 | }  | 
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| 258 | 
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: