diff --git a/cidr4_merger.py b/cidr4_merger.py
index a1d9278..bd6d4b4 100644
--- a/cidr4_merger.py
+++ b/cidr4_merger.py
@@ -138,154 +138,4 @@ def main():
 
 
 if __name__ == "__main__":
-    assert cidr4_to_node("4.78.139.0/24") == (72256256, 24, 0)
-    assert cidr4_to_node("0.0.0.0/32") == (0, 32, 0)
-
-    assert node_to_cidr4(72256256, 24) == "4.78.139.0/24"
-    assert node_to_cidr4(0, 32) == "0.0.0.0/32"
-
-    bin_a = "10011000000000001000010000010000"
-    assert len(bin_a) == 32
-    value_a = int(bin_a, 2)
-
-    bin_b = "10011100000000000000000000101011"
-    assert len(bin_b) == 32
-    value_b = int(bin_b, 2)
-
-    bin_c = "10011000000000000000000000000000"
-    assert len(bin_c) == 32
-    value_c = int(bin_c, 2)
-
-    bin_d = "11111100000000000000000000000000"
-    assert len(bin_c) == 32
-    value_d = int(bin_d, 2)
-
-    assert get_net_addr(value_a, 5) == value_c
-    assert get_net_addr(value_b, 5) == value_c
-    assert get_net_addr(0, 1) == 0
-    assert get_net_addr(0, 0) == 0
-
-    assert get_parent_mask(value_a, 6) == value_c
-    assert get_parent_mask(value_b, 6) == value_c
-    assert get_parent_mask(0, 1) == 0
-    assert get_parent_mask(0, 0) is None
-
-    assert have_same_parent(value_a, 6, value_b, 6) is True
-    assert have_same_parent(value_a, 6, value_b, 5) is False
-    assert have_same_parent(value_a, 6, value_d, 6) is False
-    assert have_same_parent(value_a, 6, 0, 1) is False
-    assert have_same_parent(value_a, 6, 0, 0) is False
-
-    assert sort_nodes(
-        [
-            (401219072, 24, 0),
-            (2899902464, 19, 0),
-            (400657664, 24, 0),
-            (520969728, 23, 0),
-        ]
-    ) == [
-        (2899902464, 19, 0),
-        (520969728, 23, 0),
-        (400657664, 24, 0),
-        (401219072, 24, 0),
-    ]
-
-    assert get_group_with_max_mask_len(
-        [
-            (2899902464, 19, 0),
-            (520969728, 23, 0),
-            (400657664, 24, 0),
-            (401219072, 24, 0),
-        ]
-    ) == [(400657664, 24, 0), (401219072, 24, 0)]
-    assert get_group_with_max_mask_len(
-        [
-            (401219072, 24, 0),
-            (2899902464, 19, 0),
-            (520969728, 23, 0),
-        ]
-    ) == [(401219072, 24, 0)]
-
-    assert get_parent((0, 2, 12), (1073741824, 2, 3)) == (0, 1, 15)
-    assert get_parent((2147483648, 2, 1), (3221225472, 2, 2)) == (2147483648, 1, 3)
-
-    assert reduce_nodes(
-        [
-            (0, 2, 12),
-            (1073741824, 2, 3),
-        ]
-    ) == [
-        (0, 1, 15),
-    ]
-
-    assert reduce_nodes(
-        [
-            (0, 2, 12),
-            (1073741824, 2, 3),
-            (2147483648, 2, 1),
-            (3221225472, 2, 2),
-        ]
-    ) == [
-        (2147483648, 1, 3),
-        (0, 2, 12),
-        (1073741824, 2, 3),
-    ]
-
-    assert reduce_nodes(
-        [
-            (0, 2, 12),
-            (2147483648, 1, 0),
-        ]
-    ) == [
-        (0, 1, 12 + 2**30),
-        (2147483648, 1, 0),
-    ]
-
-    assert reduce_nodes(
-        [
-            (0, 1, 12 + 2**30),
-            (2147483648, 1, 0),
-        ]
-    ) == [
-        (0, 0, 12 + 2**30),
-    ]
-
-    assert merge_nodes(
-        [
-            (0, 2, 12),
-            (2147483648, 2, 1),
-            (3221225472, 2, 2),
-        ],
-        2,
-    ) == [
-        (2147483648, 1, 3),
-        (0, 2, 12),
-    ]
-
-    assert merge_nodes(
-        [
-            (0, 2, 12),
-            (2147483648, 2, 1),
-            (3221225472, 2, 2),
-        ],
-        1,
-    ) == [(0, 0, 15 + 2**30)]
-
-    assert answer(
-        [
-            (0, 2, 0),
-            (2147483648, 2, 0),
-            (3221225472, 2, 12),
-        ],
-        2,
-    ) == (["128.0.0.0/1", "0.0.0.0/2"], 12)
-
-    assert answer(
-        [
-            (0, 2, 0),
-            (2147483648, 2, 0),
-        ],
-        1,
-    ) == (["0.0.0.0/0"], 2**31)
-
     cProfile.run("main()")
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_cidr4_merger.py b/tests/test_cidr4_merger.py
index 1f3b77f..d2e08bd 100644
--- a/tests/test_cidr4_merger.py
+++ b/tests/test_cidr4_merger.py
@@ -1,2 +1,191 @@
+from cidr4_merger import (
+    answer,
+    cidr4_to_node,
+    get_group_with_max_mask_len,
+    get_net_addr,
+    get_parent,
+    get_parent_mask,
+    have_same_parent,
+    merge_nodes,
+    node_to_cidr4,
+    reduce_nodes,
+    sort_nodes,
+)
+
+
 def test_true():
     assert True
+
+
+bin_a = "10011000000000001000010000010000"
+assert len(bin_a) == 32
+value_a = int(bin_a, 2)
+
+bin_b = "10011100000000000000000000101011"
+assert len(bin_b) == 32
+value_b = int(bin_b, 2)
+
+bin_c = "10011000000000000000000000000000"
+assert len(bin_c) == 32
+value_c = int(bin_c, 2)
+
+bin_d = "11111100000000000000000000000000"
+assert len(bin_c) == 32
+value_d = int(bin_d, 2)
+
+
+def test_cidr4_to_node():
+    assert cidr4_to_node("4.78.139.0/24") == (72256256, 24, 0)
+    assert cidr4_to_node("0.0.0.0/32") == (0, 32, 0)
+
+
+def test_node_to_cidr4():
+    assert node_to_cidr4(72256256, 24) == "4.78.139.0/24"
+    assert node_to_cidr4(0, 32) == "0.0.0.0/32"
+
+
+def test_get_net_addr():
+    assert get_net_addr(value_a, 5) == value_c
+    assert get_net_addr(value_b, 5) == value_c
+    assert get_net_addr(0, 1) == 0
+    assert get_net_addr(0, 0) == 0
+
+
+def test_get_parent_mask():
+    assert get_parent_mask(value_a, 6) == value_c
+    assert get_parent_mask(value_b, 6) == value_c
+    assert get_parent_mask(0, 1) == 0
+    assert get_parent_mask(0, 0) is None
+
+
+def test_have_same_parent():
+    assert have_same_parent(value_a, 6, value_b, 6) is True
+    assert have_same_parent(value_a, 6, value_b, 5) is False
+    assert have_same_parent(value_a, 6, value_d, 6) is False
+    assert have_same_parent(value_a, 6, 0, 1) is False
+    assert have_same_parent(value_a, 6, 0, 0) is False
+
+
+def test_sort_nodes():
+    assert sort_nodes(
+        [
+            (401219072, 24, 0),
+            (2899902464, 19, 0),
+            (400657664, 24, 0),
+            (520969728, 23, 0),
+        ]
+    ) == [
+        (2899902464, 19, 0),
+        (520969728, 23, 0),
+        (400657664, 24, 0),
+        (401219072, 24, 0),
+    ]
+
+
+def test_get_group_with_max_mask_len():
+    assert get_group_with_max_mask_len(
+        [
+            (2899902464, 19, 0),
+            (520969728, 23, 0),
+            (400657664, 24, 0),
+            (401219072, 24, 0),
+        ]
+    ) == [(400657664, 24, 0), (401219072, 24, 0)]
+
+    assert get_group_with_max_mask_len(
+        [
+            (401219072, 24, 0),
+            (2899902464, 19, 0),
+            (520969728, 23, 0),
+        ]
+    ) == [(401219072, 24, 0)]
+
+
+def test_get_parent():
+    assert get_parent((0, 2, 12), (1073741824, 2, 3)) == (0, 1, 15)
+    assert get_parent((2147483648, 2, 1), (3221225472, 2, 2)) == (2147483648, 1, 3)
+
+
+def test_reduce_nodes():
+    assert reduce_nodes(
+        [
+            (0, 2, 12),
+            (1073741824, 2, 3),
+        ]
+    ) == [
+        (0, 1, 15),
+    ]
+
+    assert reduce_nodes(
+        [
+            (0, 2, 12),
+            (1073741824, 2, 3),
+            (2147483648, 2, 1),
+            (3221225472, 2, 2),
+        ]
+    ) == [
+        (2147483648, 1, 3),
+        (0, 2, 12),
+        (1073741824, 2, 3),
+    ]
+
+    assert reduce_nodes(
+        [
+            (0, 2, 12),
+            (2147483648, 1, 0),
+        ]
+    ) == [
+        (0, 1, 12 + 2**30),
+        (2147483648, 1, 0),
+    ]
+
+    assert reduce_nodes(
+        [
+            (0, 1, 12 + 2**30),
+            (2147483648, 1, 0),
+        ]
+    ) == [
+        (0, 0, 12 + 2**30),
+    ]
+
+
+def test_merge_nodes():
+    assert merge_nodes(
+        [
+            (0, 2, 12),
+            (2147483648, 2, 1),
+            (3221225472, 2, 2),
+        ],
+        2,
+    ) == [
+        (2147483648, 1, 3),
+        (0, 2, 12),
+    ]
+
+    assert merge_nodes(
+        [
+            (0, 2, 12),
+            (2147483648, 2, 1),
+            (3221225472, 2, 2),
+        ],
+        1,
+    ) == [(0, 0, 15 + 2**30)]
+
+
+def test_answer():
+    assert answer(
+        [
+            (0, 2, 0),
+            (2147483648, 2, 0),
+            (3221225472, 2, 12),
+        ],
+        2,
+    ) == (["128.0.0.0/1", "0.0.0.0/2"], 12)
+
+    assert answer(
+        [
+            (0, 2, 0),
+            (2147483648, 2, 0),
+        ],
+        1,
+    ) == (["0.0.0.0/0"], 2**31)