I have found vague hints on the internet that we can speed up Unittests with an in-memory database by using the following line in our
<env name="SIMPLETEST_DB" value="sqlite://localhost/:memory:"/>
However, this will not work for me. In the method
BrowserTestBase::testLoad, I will run into the error
Undefined index: value without any further explanation. With a MySQL database, everything works fine (albeit slowly).
What is the correct way to use an in-memory sqlite database for Unittests? Must I install something? Must I put something into the settings file? Is this feature documented somewhere?