TreeNode check added for heap.py (#135)

Author: HarsheetKakar

.gitignore

@@ -64,3 +64,4 @@ __pycache__/
 .idea/
 build/
 dist/
+venv/

pydatastructs/trees/heaps.py

@@ -26,7 +26,8 @@ class DHeap(Heap):
 
     elements : list, tuple
         Optional, by default 'None'.
-        List/tuple of initial elements in Heap.
+        List/tuple of initial TreeNode in Heap.
+
 
     heap_property : str
         If the key stored in each node is
@@ -83,6 +84,9 @@ def __new__(cls, elements=None, heap_property="min", d=4):
             raise ValueError("%s is invalid heap property"%(heap_property))
         if elements is None:
             elements = DynamicOneDimensionalArray(TreeNode, 0)
+        else:
+            if not all(map(lambda x: _check_type(x, TreeNode), elements)):
+                raise ValueError("Expect a list/tuple of TreeNode got %s"%(elements))
         obj.heap = elements
         obj._last_pos_filled = obj.heap._last_pos_filled
         obj._build()

pydatastructs/trees/tests/test_heaps.py

@@ -48,6 +48,13 @@ def test_BinaryHeap():
     sorted_elements = [min_heap.extract().key for _ in range(8)]
     assert expected_sorted_elements == sorted_elements
 
+    non_TreeNode_elements = [
+                (7, 7), TreeNode(25, 25), TreeNode(100, 100),
+                TreeNode(1, 1), (2, 2), TreeNode(3, 3),
+                TreeNode(17, 17), TreeNode(19, 19), TreeNode(36, 36)
+            ]
+    assert raises(ValueError, lambda:
+                BinaryHeap(elements = non_TreeNode_elements, heap_property='min'))
 def test_TernaryHeap():
     max_heap = TernaryHeap(heap_property="max")
     assert max_heap.extract() is None