“Run” no-op input-only graphs without error.

Author: llasram

src/clojure/parkour/graph.clj

@@ -382,9 +382,10 @@ base configuration `conf` and job name `jname`."
 
 (defmethod node-fn :input
   [node conf jname]
-  (fn [^Job job]
+  (fn [& [^Job job]]
     (if-let [dseq (-> node :config first)]
-      (vary-meta dseq assoc ::mr/counters (.getCounters job)))))
+      (cond-> dseq
+        job (vary-meta assoc ::mr/counters (.getCounters job))))))
 
 (defn ^:private ensure-output-paths!
   [job]

test/parkour/graph_test.clj

@@ -208,3 +208,12 @@
                (catch Exception e
                  (-> e .getCause ex-data)))]
     (is (:from-task? info))))
+
+(deftest test-noop-input-graph
+  (th/with-config
+    (let [inpath (io/resource "word-count-input.txt")
+          indseq (text/dseq inpath)
+          word (->> (-> (pg/input indseq)
+                        (pg/fexecute (conf/ig) `noop-input-graph))
+                    (pr/first))]
+      (is (= "apple" word)))))