Fix issue with iterator

When there was only 1-item produced by an aggregating xform .hasNext was returning false.

project.clj

@@ -1,4 +1,4 @@
-(defproject net.cgrand/xforms "0.12.1"
+(defproject net.cgrand/xforms "0.12.2"
   :description "Extra transducers for Clojure"
   :url "https://github.com/cgrand/xforms"
   :license {:name "Eclipse Public License"

src/net/cgrand/xforms.cljc

@@ -479,13 +479,17 @@
             rf (xform (fn ([acc] acc) ([acc x] (.push dq (if (some? x) x NULL)) acc)))
             vopen (volatile! true)
             ensure-next #(or (some? (.peek dq))
-                           (if (and @vopen (.hasNext src-iterator))
-                             (let [acc (rf nil (.next src-iterator))]
-                               (when (reduced? acc) (vreset! vopen false))
-                               (recur))
-                             (do
-                               (rf nil)
-                               false)))]
+                           (and @vopen
+                             (if (.hasNext src-iterator)
+                               (let [acc (rf nil (.next src-iterator))]
+                                 (when (reduced? acc) 
+                                   (rf nil)
+                                   (vreset! vopen false))
+                                 (recur))
+                               (do 
+                                 (rf nil)
+                                 (vreset! vopen false)
+                                 (recur)))))]
         (reify java.util.Iterator
           (hasNext [_]
             (ensure-next))

test/net/cgrand/xforms_test.cljc

@@ -92,6 +92,8 @@
 
 #?(:clj
     (deftest iterator
+      (is (true? (.hasNext (x/iterator x/count (.iterator (range 5))))))
+      (is (is (= [5] (iterator-seq (x/iterator x/count (.iterator (range 5)))))))
       (is (= [[0 1] [1 2] [2 3] [3 4] [4]] (iterator-seq (x/iterator (x/partition 2 1 nil) (.iterator (range 5)))))))
     
     (deftest window-by-time