Length rule

src/Rule/Length.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace Morebec\Validator\Rule;
+
+
+use InvalidArgumentException;
+use Morebec\Validator\ValidationRuleInterface;
+
+class Length implements ValidationRuleInterface
+{
+    /**
+     * @var int
+     */
+    private $length;
+    /**
+     * @var string|null
+     */
+    private $message;
+
+    /**
+     * Length constructor.
+     * @param int $length
+     * @param string|null $message
+     */
+    public function __construct(
+        int $length,
+        ?string $message = null
+    )
+    {
+        if($length <0)
+            throw new InvalidArgumentException();
+        $this->length = $length;
+        $this->message = $message;
+    }
+
+    /**
+     * Validates a value according to this rule and returns if it is valid or not
+     * @param mixed $v
+     * @return bool true if valid, otherwise false
+     */
+    public function validate($v): bool
+    {
+        return strlen($v) == $this->length;
+    }
+
+    /**
+     * Returns the message to be used in case the validation did not pass
+     * @param mixed $v the value that did not pass the validation
+     * @return string
+     */
+    public function getMessage($v): string
+    {
+        return $this->message?:"'${$v}' is supposed to be exactly ".$this->length." characters long";
+    }
+}

tests/Rule/LengthTest.php

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+<?php
+
+namespace Tests\Morebec\Validator\Rule;
+
+
+use InvalidArgumentException;
+use Morebec\Validator\Rule\Length;
+use PHPUnit\Framework\TestCase;
+
+class LengthTest extends TestCase
+{
+    public function testValidate(){
+        $ruleFirst = new Length(4);
+        $ruleSecond = new Length(4,"Custom message");
+
+        $this->assertTrue($ruleFirst->validate("test"));
+        $this->assertFalse($ruleFirst->validate("test message"));
+        $this->assertEquals("Custom message",$ruleSecond->getMessage("test"));
+        $this->expectException(InvalidArgumentException::class);
+
+        $ruleThird = new Length(-1);
+    }
+}