SQLite deletes a shared in-memory database when its last connection
closes. A query cancelled while it runs makes the pool close its
connection, so a test could lose all its tables and rows at random.
The new package internal/dbtest has NewTestDatabaseURL. It returns the
URL of a new in-memory database with a random name and holds one
connection to it open until the test ends. The db, handlers,
ircserver, server and service tests take their database URL from it.
The test-support lint rule keeps the package out of the server binary.
A new test cancels a query on such a database, checks with a TEMP
table that the connection was replaced, and checks that a row is
still there.
Model: opus-5-5
