Realize DB transient rows in after-select hook before calling `driver.u/features` (#42744)

src/metabase/models/database.clj

@@ -181,7 +181,7 @@
     (cond-> database
       ;; TODO - this is only really needed for API responses. This should be a `hydrate` thing instead!
       (driver.impl/registered? driver)
-      (assoc :features (driver.u/features driver database))
+      (assoc :features (driver.u/features driver (t2.realize/realize database)))
 
       (and (driver.impl/registered? driver)
            (:details database)

test/metabase/models/database_test.clj

@@ -309,6 +309,16 @@
         (is (partial= {:details {}}
                       db))))))
 
+(deftest ^:parallel after-select-driver-features-realize-db-row-test
+  ;; This test is necessary because driver multimethods should be able to assume that the db argument is a Database
+  ;; instance, not a transient row. Otherwise a call like `(mi/instance-of :model/Database db)` will return false
+  ;; when it should return true.
+  (testing "Make sure selecting a database calls `driver/database-supports?` with a database instance"
+    (mt/with-temp [Database {db-id :id} {:engine (u/qualified-name ::test)}]
+      (mt/with-dynamic-redefs [driver/database-supports? (fn [_ _ db]
+                                                           (is (true? (mi/instance-of? :model/Database db))))]
+        (is (some? (t2/select-one-fn :features Database :id db-id)))))))
+
 (deftest hydrate-tables-test
   (is (= ["CATEGORIES"
           "CHECKINS"