Raise version min PHP 7.3.

tests/IsOneOfAssert.php

@@ -14,38 +14,34 @@ use yii\helpers\VarDumper;
  */
 class IsOneOfAssert extends \PHPUnit\Framework\Constraint\Constraint
 {
-    private $allowedValues;
-
     /**
-     * IsOneOfAssert constructor.
-     * @param array $allowedValues
+     * @var array the expected values
      */
-    public function __construct(array $allowedValues)
+    private $allowedValues = [];
+
+    public function __construct($allowedValues)
     {
-        parent::__construct();
         $this->allowedValues = $allowedValues;
     }
 
-
     /**
      * Returns a string representation of the object.
-     *
-     * @return string
      */
-    public function toString()
+    public function toString(): string
     {
-        $allowedValues = array_map(function ($value) {
-            return VarDumper::dumpAsString($value);
-        }, $this->allowedValues);
+        $allowedValues = [];
+
+        foreach ($this->allowedValues as $value) {
+            $this->allowedValues[] = VarDumper::dumpAsString($value);
+        }
+
         $expectedAsString = implode(', ', $allowedValues);
+
         return "is one of $expectedAsString";
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    protected function matches($other)
+    protected function matches($other): bool
     {
-        return in_array($other, $this->allowedValues, false);
+        return in_array($other, $this->allowedValues);
     }
 }