minor symfony#16878 [Form] Fix undefined variable (MaximePinot)

This PR was merged into the 4.4 branch.

Discussion
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[Form] Fix undefined variable

There are no variables named `$object` in this method. I think the edited line is referring to the `$expected` variable.

Commits
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2ed1cc7 [Form] Fix undefined variable

Author: OskarStark

form/unit_testing.rst

@@ -59,7 +59,7 @@ The simplest ``TypeTestCase`` implementation looks like the following::
             $form = $this->factory->create(TestedType::class, $model);
 
             $expected = new TestObject();
-            // ...populate $object properties with the data stored in $formData
+            // ...populate $expected properties with the data stored in $formData
 
             // submit the data to the form directly
             $form->submit($formData);