feat: adds support for global helpers

tests/.snapshots/success.txt

@@ -47,6 +47,12 @@
   ✓ it catch exceptions
   ✓ it catch exceptions and messages
 
+   PASS  Tests\Features\Helpers
+  ✓ it can set/get properties on $this
+  ✓ it throws error if property do not exist
+  ✓ it allows to call underlying protected/private methods
+  ✓ it throws error if method do not exist
+
    PASS  Tests\Features\HigherOrderMessages
   ✓ it proxies calls to object
 
@@ -126,5 +132,5 @@
    WARN  Tests\Visual\Success
   s visual snapshot of test suite on success
 
-  Tests:  6 skipped, 65 passed
-  Time:   2.50s
+  Tests:  6 skipped, 69 passed
+  Time:   2.63s

tests/Features/Helpers.php

@@ -0,0 +1,43 @@
+<?php
+
+function addName()
+{
+    test()->user = 'nuno';
+}
+
+it('can set/get properties on $this', function () {
+    addName();
+    assertEquals('nuno', $this->name);
+});
+
+it('throws error if property do not exist', function () {
+    test()->user;
+})->throws(\Whoops\Exception\ErrorException::class, 'Undefined property PHPUnit\Framework\TestCase::$name');
+
+class User
+{
+    public function getName()
+    {
+        return 'nuno';
+    }
+}
+
+function mockUser()
+{
+    $mock = test()->createMock(User::class);
+
+    $mock->method('getName')
+         ->willReturn('maduro');
+
+    return $mock;
+}
+
+it('allows to call underlying protected/private methods', function () {
+    $user = mockUser();
+
+    assertEquals('maduro', $user->getName());
+});
+
+it('throws error if method do not exist', function () {
+    test()->name();
+})->throws(\ReflectionException::class, 'Call to undefined method PHPUnit\Framework\TestCase::name()');