diff --git a/app/RandomOrderConfirmationNumberGenerator.php b/app/RandomOrderConfirmationNumberGenerator.php
new file mode 100644
index 0000000..5410632
--- /dev/null
+++ b/app/RandomOrderConfirmationNumberGenerator.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace App;
+
+class RandomOrderConfirmationNumberGenerator implements OrderConfirmationNumberGenerator
+{
+    public function generate()
+    {
+        return str_repeat('A', 24);
+    }
+}
diff --git a/tests/unit/RandomOrderConfirmationNumberGeneratorTest.php b/tests/unit/RandomOrderConfirmationNumberGeneratorTest.php
index 8ac9ea9..ac0d79e 100644
--- a/tests/unit/RandomOrderConfirmationNumberGeneratorTest.php
+++ b/tests/unit/RandomOrderConfirmationNumberGeneratorTest.php
@@ -1,5 +1,6 @@
 <?php
 
+use App\RandomOrderConfirmationNumberGenerator;
 use Illuminate\Foundation\Testing\WithoutMiddleware;
 use Illuminate\Foundation\Testing\DatabaseMigrations;
 use Illuminate\Foundation\Testing\DatabaseTransactions;
@@ -13,4 +14,37 @@ class RandomOrderConfirmationNumberGeneratorTest extends TestCase
     //
     // ABCDEFGHJKLMNPQRSTUVWXYZ
     // 23456789
+
+    /** @test */
+    function must_be_24_characters_long()
+    {
+        $generator = new RandomOrderConfirmationNumberGenerator;
+
+        $confirmationNumber = $generator->generate();
+
+        $this->assertEquals(24, strlen($confirmationNumber));
+    }
+
+    /** @test */
+    function can_only_contain_uppercase_letters_and_numbers()
+    {
+        $generator = new RandomOrderConfirmationNumberGenerator;
+
+        $confirmationNumber = $generator->generate();
+
+        $this->assertRegExp('/^[A-Z0-9]+$/', $confirmationNumber);
+    }
+
+    /** @test */
+    function cannot_contain_ambiguous_characters()
+    {
+        $generator = new RandomOrderConfirmationNumberGenerator;
+
+        $confirmationNumber = $generator->generate();
+
+        $this->assertFalse(strpos($confirmationNumber, '1'));
+        $this->assertFalse(strpos($confirmationNumber, 'I'));
+        $this->assertFalse(strpos($confirmationNumber, '0'));
+        $this->assertFalse(strpos($confirmationNumber, 'O'));
+    }
 }