Three tests in IntrospectionProcessorTest (testLevelTooLow, testLevelEqual, testLevelHigher) aren't actually testing anything. Because `$expected = $input` is a reference, the changes made to `$expected['extra']` are made to $input and carried forward to $actual. You can demonstrate this by adding a `return $record` at the immediate start of `InstrospectionProcessor::__invoke` -- the tests still pass despite bypassing all the code.
