Add testing of migration downgrades

Author: Nemo157

src/db/migrate.rs

@@ -337,8 +337,8 @@ pub fn migrate(version: Option<Version>, conn: &Connection) -> CratesfyiResult<(
              DROP COLUMN versions;",
             // downgrade query
             "ALTER TABLE crates
-             ADD COLUMN content,
-             ADD COLUMN versions;"
+             ADD COLUMN content tsvector,
+             ADD COLUMN versions JSON DEFAULT '[]';"
         ),
     ];
 

src/test/mod.rs

@@ -166,6 +166,7 @@ impl TestDatabase {
 
 impl Drop for TestDatabase {
     fn drop(&mut self) {
+        crate::db::migrate(Some(0), &self.conn()).expect("downgrading database works");
         if let Err(e) = self
             .conn()
             .execute(&format!("DROP SCHEMA {} CASCADE;", self.schema), &[])