add Sparse NDIter test

scala-package/core/src/main/scala/org/apache/mxnet/SparseNDArray.scala

@@ -151,6 +151,11 @@ class SparseNDArray private[mxnet] (override private[mxnet] val handle: NDArrayH
     dense.at(idx)
   }
 
+  override def slice(start: Int, end: Int): NDArray = {
+    printf(s"\n\nSlice being called!!\n\nstart:$start end:$end")
+    NDArray.api.slice(this, Shape(start), Shape(end))
+  }
+
   /**
     * Get the Data portion from the row Sparse NDArray
     * @return NDArray

scala-package/core/src/test/scala/org/apache/mxnet/SparseNDArraySuite.scala

@@ -17,6 +17,7 @@
 
 package org.apache.mxnet
 
+import org.apache.mxnet.io.NDArrayIter
 import org.scalatest.FunSuite
 import org.slf4j.LoggerFactory
 
@@ -62,7 +63,6 @@ class SparseNDArraySuite  extends FunSuite {
     )
     val indices = Array(0f, 1f, 3f)
     val rspIn = SparseNDArray.rowSparseArray(arr, indices, Shape(4, 2), Context.cpu())
-    printf(rspIn.toString)
     val toRetain = Array(0f, 3f)
     val rspOut = SparseNDArray.retain(rspIn, toRetain)
     assert(rspOut.getData.toArray sameElements Array(1f, 2f, 5f, 6f))
@@ -76,5 +76,18 @@ class SparseNDArraySuite  extends FunSuite {
     assert(nd2.toArray sameElements Array(2f, 4f, 6f))
   }
 
+  test("Test DataIter") {
+    val nd = NDArray.array(Array(1f, 2f, 3f), Shape(1, 3)).toSparse(Some(SparseFormat.CSR))
+    val arr = IndexedSeq(nd, nd, nd, nd)
+    val iter = new NDArrayIter(arr)
+    while (iter.hasNext) {
+      val tempArr = iter.next().data
+      tempArr.foreach(ele => {
+        assert(ele.sparseFormat == SparseFormat.CSR)
+        assert(ele.shape == Shape(1, 3))
+      })
+    }
+  }
+
 
 }