Add test

test/metabase/query_processor/middleware/annotate_and_sort_test.clj

@@ -11,3 +11,9 @@
                                                                            [3 nil]
                                                                            [4   5]
                                                                            [6   7]]})))
+
+;; make sure that `infer-column-types` defaults `base_type` to `type/*` if there are no non-nil
+;; values when we peek.
+(expect
+  [{:name "a", :display_name "A", :base_type :type/*}]
+  (:cols (#'annotate-and-sort/infer-column-types {:columns [:a], :rows [[nil]]})))