Added tests

tests/test_set.py

@@ -0,0 +1,37 @@
+from typing import Any, Union
+import pytest  # type: ignore
+from monads import Set
+from monads.currying import curry
+
+
+def test_fold() -> None:
+    m_set: Set[int] = Set(set([1, 2, 4]))
+    total: int = m_set.fold(lambda k, h: k + h, 0)
+    assert total == 7
+
+    @curry
+    def to_be_curried(offset: int, h: int, k: int) -> int:
+        return offset + h + k
+
+    curried_total: int = m_set.fold(to_be_curried(1), 0)
+    assert curried_total == 10
+
+
+def test_flatten() -> None:
+    m_set: Set[Union[int, Set[int]]] = Set(set([1, 2, (3, 4)]))
+    assert len(m_set.flatten()) == 4
+
+
+def test_loop() -> None:
+    m_set: Set[int] = Set(set([1, 2, 4]))
+    x = 0
+    for i in m_set:
+        x = x + 1
+    assert x == 3
+
+
+def test_len() -> None:
+    m_set: Set[int] = Set(set([1, 2, 4]))
+    assert len(m_set) == 3
+    assert m_set
+    assert not Set.mzero()