Documentation should recommend testing with pragma legacy_alter_table=on

[simonw]

See here:

• Error applying migration m008_reply_to_id_foreign_key llm#162 (comment)

[simonw]

The resolution of this bug was protected by this test:

def test_migrations_with_legacy_alter_table():
    db = sqlite_utils.Database(memory=True)
    db.execute("pragma legacy_alter_table=on")
    migrate(db)

When I write testing documentation for this package I should include that as a recommendation - or maybe even suggest a pattern like this:

@pytest.mark.parametrize("legacy_alter_table", (True, False))
def test_migrations_with_legacy_alter_table(legacy_alter_table):
    db = sqlite_utils.Database(memory=True)
    db.execute("pragma legacy_alter_table={}".format("on" if legacy_alter_table else "off"))
    migrate(db)

[simonw]

Another pattern that could work here: build a sqlite-utils plugin that turns that mode on for all connections, then show people how to use a GitHub Actions matrix build to run their tests twice, once with and once without that plugin.