Steps to reproduce the issue

I want to have look at the integration tests. I found this Read.me:

After

1. Checkout the current Joomla 4.0 development branch from Github
2. Run composer install in the root
3. Run libraries/vendor/bin/phpunit

I saw this error message.

$ libraries/vendor/bin/phpunit
PHPUnit 8.3.4 by Sebastian Bergmann and contributors.

....................WWW.W......................................  63 / 540 ( 11%)
.........................................S..................... 126 / 540 ( 23%)
....................................R.......................... 189 / 540 ( 35%)
............................................................... 252 / 540 ( 46%)
............................................................... 315 / 540 ( 58%)
............................................................... 378 / 540 ( 70%)
............................................................... 441 / 540 ( 81%)
............................................................... 504 / 540 ( 93%)
............................EEEEEEEE                            540 / 540 (100%)

Time: 955 ms, Memory: 22.00 MB

There were 8 errors:

1) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testObjectHasAttributesFromTable
Joomla\Database\Exception\ConnectionFailureException: Could not connect to database: php_network_getaddresses: getaddrinfo failed: Name or service not known

/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:273
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1844
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

2) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testBindWorksWithArraysAndObjects
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

3) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testBindOnlyBindsTableFields
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

4) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testBindIgnoresFields
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

5) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testBindJSONEncodesFields
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

6) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testBindRequiresArrayOrObject
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

7) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testBindFiresEvents
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

8) Joomla\Tests\Integration\Libraries\Cms\Table\TableTest::testReset
mysqli::prepare(): invalid object or resource mysqli


/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliStatement.php:137
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:1035
/var/www/html/joomla-cms4/libraries/vendor/joomla/database/src/DatabaseDriver.php:1891
/var/www/html/joomla-cms4/tests/Integration/DBTestHelper.php:80
/var/www/html/joomla-cms4/tests/Integration/IntegrationTestCase.php:29
/var/www/html/joomla-cms4/tests/Integration/Libraries/Cms/Table/TableTest.php:45

--

There were 4 warnings:

1) Joomla\Tests\Unit\Libraries\Cms\Document\DocumentTest::testInjectingOptionsIntoTheObjectConstructor with data set #0 (array('\n'), array('\n', 'utf-8', 'en-gb', 'ltr', '	', '', ''))
assertAttributeSame() is deprecated and will be removed in PHPUnit 9.
readAttribute() is deprecated and will be removed in PHPUnit 9.
getObjectAttribute() is deprecated and will be removed in PHPUnit 9.

2) Joomla\Tests\Unit\Libraries\Cms\Document\DocumentTest::testInjectingOptionsIntoTheObjectConstructor with data set #1 (array('euc-jp', '1a2b3c4d'), array('\n', 'euc-jp', 'en-gb', 'ltr', '	', '', '', '1a2b3c4d'))
assertAttributeSame() is deprecated and will be removed in PHPUnit 9.
readAttribute() is deprecated and will be removed in PHPUnit 9.
getObjectAttribute() is deprecated and will be removed in PHPUnit 9.

3) Joomla\Tests\Unit\Libraries\Cms\Document\DocumentTest::testInjectingOptionsIntoTheObjectConstructor with data set #2 (array('de-de', 'rtl', 'Crazy Tab', 'http://joomla.org', 'http://base.joomla.org/dir'), array('\n', 'utf-8', 'de-de', 'rtl', 'Crazy Tab', 'http://joomla.org', 'http://base.joomla.org/dir'))
assertAttributeSame() is deprecated and will be removed in PHPUnit 9.
readAttribute() is deprecated and will be removed in PHPUnit 9.
getObjectAttribute() is deprecated and will be removed in PHPUnit 9.

4) Joomla\Tests\Unit\Libraries\Cms\Document\DocumentTest::testRetrievingANonExistantTypeFetchesARawDocument
assertAttributeSame() is deprecated and will be removed in PHPUnit 9.
readAttribute() is deprecated and will be removed in PHPUnit 9.
getObjectAttribute() is deprecated and will be removed in PHPUnit 9.

--

There was 1 risky test:

1) Joomla\Tests\Unit\Libraries\Cms\Feed\Parser\AtomParserTest::testProcessFeedEntry
This test did not perform any assertions

/var/www/html/joomla-cms4/tests/Unit/Libraries/Cms/Feed/Parser/AtomParserTest.php:385

ERRORS!
Tests: 540, Assertions: 879, Errors: 8, Warnings: 4, Skipped: 1, Risky: 1.

What do I am wrong?