Enhancement: Implement UnwrapArrayDiff mutator

[localheinz]

This PR

• Adds new feature UnwrapArrayDiff mutator
• Covered by tests
• Doc PR: Enhancement: Implement UnwrapArrayDiff mutator site#83

Related to #514.

💁‍♂️ Follows the example in #513.

[maks-rafalko]

Should it be array_diff($a, $b); -> $a; as described in #514 or array_diff($a, $b); -> $a;, $b; as it's currently implemented?

what are the arguments?

cc @sanmai

[sanmai]

array_diff($a, $b); -> $a;, $b; seems like a good idea at first, but it is not hard to notice that only a very lousy test will notice$bs instead of $as because array_diff is supposed to return everything but elements of $b.

Otherwise put, these two mutations are equivalent. If you have a test against mutation $a, it'll surely catch mutation $b. That's why I decided against both when editing #514.

[localheinz]

@borNfreee @sanmai

Note that it is possible to pass more than two parameters to array_diff().

[sanmai]

True, but in my mind mutating array_diff to either $b, $c, or $d, is equivalent to mutating into $a; but I'd rather be mistaken. If there's a formidable case, we shall consider all variants of this mutation.

[localheinz]

Apparently AppVeyor is running out of memory?

See https://ci.appveyor.com/project/borNfreee/infection/builds/20127249/job/sgr0c2rynpfostfg:

PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 4096 bytes) in C:\projects\workspace\vendor\nikic\php-parser\lib\PhpParser\ParserAbstract.php on line 283
195PHP Stack trace:
196PHP   1. {main}() C:\projects\workspace\vendor\phpunit\phpunit\phpunit:0
197PHP   2. PHPUnit\TextUI\Command::main() C:\projects\workspace\vendor\phpunit\phpunit\phpunit:53
198PHP   3. PHPUnit\TextUI\Command->run() C:\projects\workspace\vendor\phpunit\phpunit\src\TextUI\Command.php:148
199PHP   4. PHPUnit\TextUI\TestRunner->doRun() C:\projects\workspace\vendor\phpunit\phpunit\src\TextUI\Command.php:195
200PHP   5. PHPUnit\Framework\TestSuite->run() C:\projects\workspace\vendor\phpunit\phpunit\src\TextUI\TestRunner.php:545
201PHP   6. PHPUnit\Framework\TestSuite->run() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestSuite.php:755
202PHP   7. PHPUnit\Framework\DataProviderTestSuite->run() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestSuite.php:755
203PHP   8. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->run() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestSuite.php:755
204PHP   9. PHPUnit\Framework\TestResult->run() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestCase.php:894
205PHP  10. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->runBare() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestResult.php:698
206PHP  11. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->runTest() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestCase.php:939
207PHP  12. ReflectionMethod->invokeArgs() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestCase.php:1071
208PHP  13. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->test_mutator() C:\projects\workspace\vendor\phpunit\phpunit\src\Framework\TestCase.php:1071
209PHP  14. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->doTest() C:\projects\workspace\tests\Mutator\FunctionSignature\PublicVisibilityTest.php:76
210PHP  15. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->mutate() C:\projects\workspace\tests\Mutator\AbstractMutatorTestCase.php:79
211PHP  16. Infection\Tests\Mutator\FunctionSignature\PublicVisibilityTest->getMutationsFromCode() C:\projects\workspace\tests\Mutator\AbstractMutatorTestCase.php:122
212PHP  17. PhpParser\Parser\Multiple->parse() C:\projects\workspace\tests\Mutator\AbstractMutatorTestCase.php:149
213PHP  18. PhpParser\Parser\Multiple->tryParse() C:\projects\workspace\vendor\nikic\php-parser\lib\PhpParser\Parser\Multiple.php:32
214PHP  19. PhpParser\Parser\Php7->parse() C:\projects\workspace\vendor\nikic\php-parser\lib\PhpParser\Parser\Multiple.php:51
215PHP  20. PhpParser\Parser\Php7->doParse() C:\projects\workspace\vendor\nikic\php-parser\lib\PhpParser\ParserAbstract.php:157
216PHP  21. PhpParser\Parser\Php7->PhpParser\Parser\{closure}() C:\projects\workspace\vendor\nikic\php-parser\lib\PhpParser\ParserAbstract.php:283

[maks-rafalko]

Apparently AppVeyor is running out of memory?

seems like appveyor now set up with 128Mb memory limit, while infection requires 200Mb+ for unit tests

#560

[maks-rafalko]

Thank you @localheinz

[localheinz]

Thank you, @borNfreee!