Issue #3204764 by longwave, mondrake: PHPUnit assertions do not return a value

core/lib/Drupal/Core/Test/AssertMailTrait.php

core/modules/filter/tests/src/Kernel/FilterKernelTest.php

...ath_alias/tests/src/Functional/UrlAlterFunctionalTest.php

...ules/system/tests/src/Functional/Form/ConfirmFormTest.php

...les/system/tests/src/Functional/Module/ModuleTestBase.php

.../system/tests/src/Functional/Session/SessionHttpsTest.php

...s/system/tests/src/Functional/System/ErrorHandlerTest.php

...dules/views/tests/src/Functional/Handler/FieldWebTest.php

...les/views/tests/src/Functional/Plugin/ExposedFormTest.php

.../views/tests/src/Kernel/Entity/RowEntityRenderersTest.php

...odules/views/tests/src/Kernel/Handler/FieldKernelTest.php

core/tests/Drupal/KernelTests/AssertContentTrait.php

...s/Drupal/KernelTests/Core/Database/ConnectionUnitTest.php

...ests/Drupal/KernelTests/Core/Database/TransactionTest.php

...upal/KernelTests/Core/Entity/EntityQueryAggregateTest.php

...ernelTests/Core/Entity/FieldTranslationSqlStorageTest.php

...l/KernelTests/Core/Plugin/Discovery/DiscoveryTestBase.php