Fix bug where flat_pmap can return nil

lib/twitter/utils.rb

@@ -22,7 +22,7 @@ def deprecate_alias(new_name, old_name, &block)
     # @return [Array, Enumerator]
     def flat_pmap(enumerable)
       return to_enum(:flat_pmap, enumerable) unless block_given?
-      pmap(enumerable, &Proc.new).flatten!(1)
+      pmap(enumerable, &Proc.new).flatten(1)
     end
     module_function :flat_pmap
 

spec/twitter/utils_spec.rb

@@ -3,6 +3,16 @@
 
 describe Twitter::Utils do
   describe '#pmap' do
+    it 'returns an array' do
+      expect(subject.flat_pmap([], &:reverse)).to be_an(Array)
+    end
+
+    it 'behaves like map' do
+      array = (0..9).to_a
+      block = proc { |x| x + 1 }
+      expect(subject.pmap(array, &block)).to eq(array.collect(&block))
+    end
+
     it 'maps in parallel' do
       delay = 0.1
       array = (0..9).to_a
@@ -18,6 +28,22 @@
   end
 
   describe '#flat_pmap' do
+    it 'always returns an array' do
+      expect(subject.flat_pmap([], &:reverse)).to be_an(Array)
+    end
+
+    it 'behaves like map for a flat array' do
+      array = (0..9).to_a
+      block = proc { |x| x + 1 }
+      expect(subject.flat_pmap(array, &block)).to eq(array.collect(&block))
+    end
+
+    it 'behaves like flat_map' do
+      array = (0..4).to_a.combination(2).to_a
+      block = proc { |x| x.reverse }
+      expect(subject.flat_pmap(array, &block)).to eq(array.collect(&block).flatten(1))
+    end
+
     it 'flat maps in parallel' do
       delay = 0.1
       array = (0..4).to_a.combination(2).to_a