diff --git a/blockchain/test/test_blockchain.py b/blockchain/test/test_blockchain.py
new file mode 100644
index 000000000..bd7e51ad8
--- /dev/null
+++ b/blockchain/test/test_blockchain.py
@@ -0,0 +1,47 @@
+import unittest
+from blockchain import Blockchain
+
+class TestBlockchain(unittest.TestCase):
+    def setUp(self):
+        self.blockchain = Blockchain()
+
+    def test_create_genesis_block(self):
+        genesis_block = self.blockchain.create_genesis_block()
+        self.assertEqual(genesis_block.index, 0)
+        self.assertEqual(genesis_block.previous_hash, '0' * 64)
+        self.assertIsNotNone(genesis_block.timestamp)
+        self.assertEqual(genesis_block.data, 'Genesis Block')
+        self.assertEqual(genesis_block.hash, '0' * 64)
+
+    def test_calculate_hash(self):
+        block = self.blockchain.create_genesis_block()
+        block.data = 'New Data'
+        block.hash = None
+        calculated_hash = self.blockchain.calculate_hash(block.index, block.previous_hash, block.timestamp, block.data)
+        self.assertEqual(calculated_hash, '0' * 64)
+
+    def test_is_chain_valid(self):
+        self.assertTrue(self.blockchain.is_chain_valid(self.blockchain.chain))
+
+        invalid_chain = self.blockchain.chain[:-1]
+        invalid_chain.append(Block(len(invalid_chain), invalid_chain[-1].hash, int(time.time()), 'Invalid Data', None))
+        self.assertFalse(self.blockchain.is_chain_valid(invalid_chain))
+
+    def test_add_block(self):
+        self.blockchain.add_block('Test Data')
+        self.assertEqual(len(self.blockchain.chain), 2)
+        self.assertEqual(self.blockchain.chain[-1].data, 'Test Data')
+
+    def test_replace_chain(self):
+        self.blockchain.replace_chain(self.blockchain.chain[:-1])
+        self.assertEqual(len(self.blockchain.chain), 1)
+
+        invalid_chain = self.blockchain.chain[:-1]
+        invalid_chain.append(Block(len(invalid_chain), invalid_chain[-1].hash, int(time.time()), 'Invalid Data', None))
+        self.blockchain.replace_chain(invalid_chain)
+        self.assertFalse(self.blockchain.is_chain_valid(self.blockchain.chain))
+
+        valid_chain = self.blockchain.chain[:-1]
+        valid_chain.append(Block(len(valid_chain), valid_chain[-1].hash, int(time.time()), 'Valid Data', None))
+        self.blockchain.replace_chain(valid_chain)
+        self.assertTrue(self.blockchain.is_chain_valid(self.blockchain.chain))