feat(helpers): adds helpers file

tests/Features/Mocks.php

@@ -6,7 +6,7 @@ interface Foo
 }
 
 it('has bar', function () {
-    $mock = Mockery::mock(Foo::class);
+    $mock = mock(Foo::class);
     $mock->shouldReceive('bar')
         ->times(1)
         ->andReturn(2);

tests/Helpers.php

@@ -0,0 +1,8 @@
+<?php
+
+use Mockery\MockInterface;
+
+function mock(string $class): MockInterface
+{
+    return Mockery::mock($class);
+}