Validation test added

tests/transactions/validation.py

@@ -0,0 +1,34 @@
+from tests.helpers import random_encoded_account_number
+
+from thenewboston.transactions.validation import validate_transaction_exists
+
+
+def test_validate_transaction_exists():
+    account = random_encoded_account_number()
+    amount = 1
+    fee = 1
+    error = RuntimeError
+    transactions = [
+        {
+            'amount': amount,
+            'fee': fee,
+            'recipient': account,
+        },
+        {
+            'amount': 2,
+            'fee': fee,
+            'recipient': account,
+        },
+    ]
+    try:
+        validate_transaction_exists(amount=amount, fee=fee, error=error, recipient=account, txs=transactions)
+        validate_transaction_exists(amount=amount + 1, fee=fee, error=error, recipient=account, txs=transactions)
+        assert True
+    except error:
+        raise AssertionError()
+    try:
+        validate_transaction_exists(amount=amount, fee=3, error=error, recipient=account, txs=transactions)
+        validate_transaction_exists(amount=amount, fee=fee, error=error, recipient=random_encoded_account_number(), txs=transactions)
+        assert AssertionError()
+    except error:
+        assert True