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 // phpcs:ignore WordPress.Files.FileName |
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| 18 | class Test_Autoloader_Scenarios extends TestCase { |
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| 19 | |||
| 20 | /** |
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| 21 | * Indicates whether or not the autoloader has been reset by a load operation. |
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| 22 | * |
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| 23 | * @var bool |
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| 24 | */ |
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| 25 | private $autoloader_reset; |
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| 26 | |||
| 27 | /** |
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| 28 | * Setup runs before each test. |
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| 29 | * |
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| 30 | * @before |
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| 31 | */ |
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| 32 | public function set_up() { |
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| 41 | |||
| 42 | /** |
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| 43 | * Teardown runs after each test. |
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| 44 | * |
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| 45 | * @after |
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| 46 | */ |
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| 47 | public function tear_down() { |
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| 57 | |||
| 58 | /** |
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| 59 | * Tests that the autoloader works as expected. |
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| 60 | */ |
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| 61 | public function test_autoloader_init() { |
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| 62 | $this->activate_plugin( 'plugin_current' ); |
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| 63 | |||
| 64 | $this->load_autoloader( 'plugin_current' ); |
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| 65 | |||
| 66 | $this->assertAutoloaderVersion( '2.6.0.0' ); |
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| 67 | |||
| 68 | $this->shutdown_autoloader( true ); |
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| 69 | $this->assertAutoloaderCache( array( 'plugin_current' ) ); |
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| 70 | } |
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| 71 | |||
| 72 | /** |
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| 73 | * Tests that the autoloader does not initialize twice. |
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| 74 | */ |
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| 75 | public function test_autoloader_init_once() { |
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| 87 | |||
| 88 | /** |
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| 89 | * Tests that the autoloader loads the latest when loading an older one first. |
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| 90 | */ |
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| 91 | View Code Duplication | public function test_autoloader_loads_latest() { |
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| 104 | |||
| 105 | /** |
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| 106 | * Tests that the autoloader does not conflict with a v1 autoloader. |
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| 107 | */ |
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| 108 | public function test_autoloader_overrides_v1() { |
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| 121 | |||
| 122 | /** |
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| 123 | * Tests that the autoloader is not reset when an older V2 initializes after the latest. |
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| 124 | */ |
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| 125 | View Code Duplication | public function test_autoloader_not_reset_by_older_v2() { |
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| 138 | |||
| 139 | /** |
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| 140 | * Tests that the autoloader resets when an unknown plugin is encountered, and that it does not |
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| 141 | * reset a second time once the unknown plugin has been recorded. |
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| 142 | */ |
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| 143 | public function test_autoloader_resets_when_unknown_plugin_is_encountered() { |
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| 155 | |||
| 156 | /** |
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| 157 | * Tests that the autoloader uses the cache to avoid resetting when an known plugin is encountered. |
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| 158 | */ |
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| 159 | View Code Duplication | public function test_autoloader_uses_cache_to_avoid_resets() { |
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| 174 | |||
| 175 | /** |
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| 176 | * Tests that the autoloader updates the cache. |
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| 177 | */ |
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| 178 | public function test_autoloader_updates_cache() { |
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| 179 | $this->activate_plugin( 'plugin_current' ); |
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| 180 | |||
| 181 | // Write an empty cache so we can make sure it was updated. |
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| 182 | $this->cache_plugins( array() ); |
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| 183 | |||
| 184 | $this->load_autoloader( 'plugin_current' ); |
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| 185 | $this->shutdown_autoloader( true ); |
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| 186 | |||
| 187 | $this->assertAutoloaderVersion( '2.6.0.0' ); |
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| 188 | $this->assertAutoloaderCache( array( 'plugin_current' ) ); |
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| 189 | } |
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| 190 | |||
| 191 | /** |
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| 192 | * Tests that the autoloader does not update the cache if it has not changed. |
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| 193 | */ |
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| 194 | public function test_autoloader_does_not_update_unchanged_cache() { |
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| 211 | |||
| 212 | /** |
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| 213 | * Tests that the autoloader empties the cache if shutdown happens before plugins_loaded. |
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| 214 | */ |
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| 215 | public function test_autoloader_empties_cache_on_early_shutdown() { |
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| 216 | $this->activate_plugin( 'plugin_current' ); |
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| 217 | |||
| 218 | // Write a cache that we can use when loading the autoloader. |
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| 219 | $this->cache_plugins( array( 'plugin_current' ) ); |
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| 220 | |||
| 221 | $this->load_autoloader( 'plugin_current' ); |
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| 222 | |||
| 223 | // Make sure to shutdown prematurely so that the cache will be erased instead of saved. |
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| 224 | $this->shutdown_autoloader( false ); |
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| 225 | |||
| 226 | $this->assertAutoloaderVersion( '2.6.0.0' ); |
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| 227 | $this->assertAutoloaderCache( array() ); |
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| 228 | } |
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| 229 | |||
| 230 | /** |
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| 231 | * Tests that the autoloader is able to resolve symbolic links to avoid duplicate plugin entries. |
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| 232 | */ |
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| 233 | public function test_autoloader_resolves_symlinks() { |
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| 234 | $this->activate_plugin( 'plugin_current', 'plugin_symlink' ); |
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| 235 | |||
| 236 | $this->load_autoloader( 'plugin_symlink' ); |
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| 237 | |||
| 238 | $this->assertAutoloaderVersion( '2.6.0.0' ); |
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| 239 | |||
| 240 | $this->shutdown_autoloader( true ); |
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| 241 | // Since there's no cache we should expect the resolved path. |
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| 242 | $this->assertAutoloaderCache( array( 'plugin_current' ) ); |
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| 243 | } |
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| 244 | |||
| 245 | /** |
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| 246 | * Tests that the autoloader can handle cases where the cached path is a symlink. |
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| 247 | */ |
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| 248 | public function test_autoloader_resolves_cached_symlinks() { |
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| 249 | $this->cache_plugins( array( 'plugin_symlink' ) ); |
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| 250 | |||
| 251 | $this->activate_plugin( 'plugin_current', 'plugin_symlink' ); |
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| 252 | |||
| 253 | $this->load_autoloader( 'plugin_symlink' ); |
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| 254 | |||
| 255 | $this->assertAutoloaderVersion( '2.6.0.0' ); |
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| 256 | |||
| 257 | $this->shutdown_autoloader( true ); |
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| 258 | // The cache shouldn't be updated since internally real paths are always used. |
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| 259 | $this->assertAutoloaderCache( array( 'plugin_symlink' ) ); |
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| 260 | } |
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| 261 | |||
| 262 | /** |
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| 263 | * Generates a new autoloader from the current source files for the "plugin_current" plugin. |
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| 264 | * |
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| 265 | * @param string $plugin The plugin to generate the autoloader for. |
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| 266 | */ |
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| 267 | private function generate_autoloader( $plugin ) { |
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| 286 | |||
| 287 | /** |
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| 288 | * "Activate" a plugin so that the autoloader can detect it. |
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| 289 | * |
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| 290 | * @param string $plugin The plugin we want to activate. |
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| 291 | * @param string $folder The folder that the plugin is in. If empty this will default to $plugin. |
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| 292 | */ |
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| 293 | private function activate_plugin( $plugin, $folder = '' ) { |
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| 307 | |||
| 308 | /** |
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| 309 | * Loads the given autoloader and initializes it. |
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| 310 | * |
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| 311 | * @param string $plugin The plugin to load the autoloader from. |
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| 312 | */ |
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| 313 | private function load_autoloader( $plugin ) { |
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| 327 | |||
| 328 | /** |
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| 329 | * Writes the plugins to the cache so that they can be read by the autoloader. |
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| 330 | * |
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| 331 | * @param string[] $plugins The plugins to cache. |
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| 332 | */ |
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| 333 | private function cache_plugins( $plugins ) { |
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| 344 | |||
| 345 | /** |
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| 346 | * Runs the autoloader's shutdown action. |
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| 347 | * |
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| 348 | * @param bool $plugins_loaded Indicates whether or not the plugins_loaded action should have fired. |
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| 349 | */ |
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| 350 | private function shutdown_autoloader( $plugins_loaded = true ) { |
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| 357 | |||
| 358 | /** |
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| 359 | * Asserts that the latest autoloader version is the one given. |
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| 360 | * |
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| 361 | * @param string $version The version to check. |
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| 362 | */ |
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| 363 | private function assertAutoloaderVersion( $version ) { |
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| 370 | |||
| 371 | /** |
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| 372 | * Asserts that the autoloader cache contains the plugins given. |
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| 373 | * |
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| 374 | * @param array $plugins The plugins to check the cache for. |
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| 375 | */ |
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| 376 | private function assertAutoloaderCache( $plugins ) { |
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| 390 | } |
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| 391 |
Let’s assume that you have a directory layout like this:
. |-- OtherDir | |-- Bar.php | `-- Foo.php `-- SomeDir `-- Foo.phpand let’s assume the following content of
Bar.php:If both files
OtherDir/Foo.phpandSomeDir/Foo.phpare loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.phpHowever, as
OtherDir/Foo.phpdoes not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: