Added tests for empty free construction

Author: FamALouiz

pydatastructs/trees/tests/test_binary_trees.py

@@ -821,6 +821,47 @@ def test_cpp_RedBlackTree():
 
 
 def _test_FusionTree(backend):
+    FT = FusionTree
+    f_tree = FT(backend=backend)
+
+    f_tree.insert(8, 8)
+    f_tree.insert(3, 3)
+    f_tree.insert(10, 10)
+    f_tree.insert(1, 1)
+    f_tree.insert(6, 6)
+    f_tree.insert(4, 4)
+    f_tree.insert(7, 7)
+    f_tree.insert(14, 14)
+    f_tree.insert(13, 13)
+
+    assert f_tree.search(10) is not None
+    assert f_tree.search(-1) is None
+
+    assert f_tree.delete(13) is True
+    assert f_tree.search(13) is None
+    assert f_tree.delete(10) is True
+    assert f_tree.search(10) is None
+    assert f_tree.delete(3) is True
+    assert f_tree.search(3) is None
+    assert f_tree.delete(13) is False  # Already deleted
+
+    expected_str = '[(8, 8), (1, 1), (6, 6), (4, 4), (7, 7), (14, 14)]'
+    assert str(f_tree) == expected_str
+
+    f_tree.insert(8, 9)
+    assert f_tree.search(8) is not None
+
+    large_key = 10**9
+    f_tree.insert(large_key, large_key)
+    assert f_tree.search(large_key) is not None
+
+    expected_str = '[(8, 8), (1, 1), (6, 6), (4, 4), (7, 7), (14, 14), (8, 9), (1000000000, 1000000000)]'
+    assert str(f_tree) == expected_str
+    assert f_tree.delete(8) is True
+
+    expected_str = '[(1, 1), (6, 6), (4, 4), (7, 7), (14, 14), (8, 9), (1000000000, 1000000000)]'
+    assert str(f_tree) == expected_str
+
     FT = FusionTree
     f_tree = FT(8, 8, backend=backend)