Nil pad results of last-n when (count seq) < n

src/metabase/sync/analyze/fingerprint/insights.clj

@@ -11,7 +11,8 @@
   [n]
   (fn
     ([] [])
-    ([acc] acc)
+    ([acc]
+     (concat (repeat (- n (count acc)) nil) acc))
     ([acc x]
      (if (< (count acc) n)
        (conj acc x)

test/metabase/sync/analyze/fingerprint/insights_test.clj

@@ -15,9 +15,21 @@
       first
       :last-value))
 
+(expect
+  700
+  (-> (transduce identity (insights cols) [["2017" 700]])
+      first
+      :last-value))
+
 ;; Here we just make sure we don't blow up on empty input
 (expect
   nil
   (-> (transduce identity (insights cols) [])
       first
       :last-value))
+
+(expect
+  nil
+  (-> (transduce identity (insights cols) [[nil nil]])
+      first
+      :last-value))