minor #8971 Fixed an example in the form testing article (javiereguiluz)

This PR was merged into the 2.7 branch.

Discussion
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Fixed an example in the form testing article

This fixes #8970.

Commits
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36c183e Fixed an example in the form testing article

Author: javiereguiluz

form/unit_testing.rst

@@ -55,7 +55,8 @@ The simplest ``TypeTestCase`` implementation looks like the following::
             $type = new TestedType();
             $form = $this->factory->create($type);
 
-            $object = TestObject::fromArray($formData);
+            $object = new TestObject();
+            // ...populate $object properties with the data stored in $formData
 
             // submit the data to the form directly
             $form->submit($formData);