Логика генерации значения первичного ключа для строк вынесена в поведение

tests/codeception/common/unit/behaviors/PrimaryKeyValueBehaviorTest.php

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+<?php
+namespace codeception\common\unit\behaviors;
+
+use Codeception\Specify;
+use common\behaviors\PrimaryKeyValueBehavior;
+use tests\codeception\api\unit\TestCase;
+use yii\db\ActiveRecord;
+
+class PrimaryKeyValueBehaviorTest extends TestCase {
+    use Specify;
+
+    public function testSetPrimaryKeyValue() {
+        $this->specify('method should generate value for primary key field on call', function() {
+            $model = new DummyModel();
+            /** @var PrimaryKeyValueBehavior|\PHPUnit_Framework_MockObject_MockObject $behavior */
+            $behavior = $this->getMockBuilder(PrimaryKeyValueBehavior::class)
+                 ->setMethods(['isValueExists'])
+                 ->setConstructorArgs([[
+                     'value' => function() {
+                         return 'mock';
+                     },
+                 ]])
+                 ->getMock();
+
+            $behavior->expects($this->once())
+                     ->method('isValueExists')
+                     ->will($this->returnValue(false));
+
+            $model->attachBehavior('primary-key-value-behavior', $behavior);
+            $behavior->setPrimaryKeyValue();
+            expect($model->id)->equals('mock');
+        });
+
+        $this->specify('method should repeat value generation if generated value duplicate with exists', function() {
+            $model = new DummyModel();
+            /** @var PrimaryKeyValueBehavior|\PHPUnit_Framework_MockObject_MockObject $behavior */
+            $behavior = $this->getMockBuilder(PrimaryKeyValueBehavior::class)
+                ->setMethods(['isValueExists', 'generateValue'])
+                ->setConstructorArgs([[
+                    'value' => function() {
+                        return 'this was mocked, but let be passed';
+                    },
+                ]])
+                ->getMock();
+
+            $behavior->expects($this->exactly(3))
+                  ->method('generateValue')
+                  ->will($this->onConsecutiveCalls('1', '2', '3'));
+
+            $behavior->expects($this->exactly(3))
+                  ->method('isValueExists')
+                  ->will($this->onConsecutiveCalls(true, true, false));
+
+            $model->attachBehavior('primary-key-value-behavior', $behavior);
+            $behavior->setPrimaryKeyValue();
+            expect($model->id)->equals('3');
+        });
+    }
+
+}
+
+class DummyModel extends ActiveRecord {
+
+    public $id;
+
+    public static function primaryKey() {
+        return ['id'];
+    }
+
+}