standard library: 'sum' function added (KT-3714, KT-3843, KT-3126)

libraries/stdlib/test/ArraysJVMTest.kt

@@ -58,4 +58,14 @@ class ArraysJVMTest {
             intArray().reduceRight { a, b -> a + b}
         }
     }
+
+    test fun sum() {
+        expect(0) { intArray().sum() }
+        expect(14) { intArray(2, 3, 9).sum() }
+        expect(3.0) { doubleArray(1.0, 2.0).sum() }
+        expect(200) { byteArray(100, 100).sum() }
+        expect(50000) { shortArray(20000, 30000).sum() }
+        expect(3000000000000) { longArray(1000000000000, 2000000000000).sum() }
+        expect(3.0) { floatArray(1.0, 2.0).sum() }
+    }
 }

libraries/stdlib/test/ArraysTest.kt

@@ -101,6 +101,16 @@ class ArraysTest {
         assertEquals(false, arr[1])
     }
 
+    test fun sum() {
+        expect(0) { array<Int>().sum() }
+        expect(14) { array(2, 3, 9).sum() }
+        expect(3.0) { array(1.0, 2.0).sum() }
+        expect(200) { array<Byte>(100, 100).sum() }
+        expect(50000) { array<Short>(20000, 30000).sum() }
+        //TODO: uncomment when toLong() will be supported
+        //expect(3000000000000) { array<Long>(1000000000000, 2000000000000).sum() }
+        expect(3.0) { array<Float>(1.0, 2.0).sum() }
+    }
     /*
 
     TODO FIXME ASAP: These currently fail on JS due to missing upto() method on numbers

libraries/stdlib/test/CollectionTest.kt

@@ -414,6 +414,14 @@ class CollectionTest {
         expect(arrayList(2, 3, 1)) { list }
     }
 
+    test fun sum() {
+        expect(0) { ArrayList<Int>().sum() }
+        expect(14) { arrayListOf(2, 3, 9).sum() }
+        expect(3.0) { arrayListOf(1.0, 2.0).sum() }
+        expect(3000000000000) { arrayListOf<Long>(1000000000000, 2000000000000).sum() }
+        expect(3.0) { arrayListOf<Float>(1.0, 2.0).sum() }
+    }
+
     class IterableWrapper<T>(collection : Iterable<T>) : Iterable<T> {
         private val collection = collection