test: example web3py usage

tools/web3py-example/.env.example

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+OPERATOR_PRIVATE_KEY=
+RELAY_ENDPOINT=

tools/web3py-example/.gitignore

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+.env

tools/web3py-example/README.md

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+# Web3py example
+Example scripts for basic operations
+
+### How to start
+1. **Install Solidity Compiler (`solc`)**:
+    - Install `solc` by following the instructions in the [Solidity documentation](https://docs.soliditylang.org/en/latest/installing-solidity.html).
+    - On Ubuntu, you can run:
+      ```sh
+      sudo apt install solc
+      ```
+
+2. **Set up a clean environment (with virtual env)**
+
+```bash
+# Install pip if it is not available:
+$ which pip || curl https://bootstrap.pypa.io/get-pip.py | python
+
+# Install virtualenv if it is not available:
+$ which virtualenv || pip install --upgrade virtualenv
+
+# *If* the above command displays an error, you can try installing as root:
+$ sudo pip install virtualenv
+
+# Create a virtual environment:
+$ virtualenv -p python3 ~/.venv-py3
+
+# Activate your new virtual environment:
+$ source ~/.venv-py3/bin/activate
+
+# With virtualenv active, make sure you have the latest packaging tools
+$ pip install --upgrade pip setuptools
+
+# Now we can install web3.py...
+$ pip install --upgrade web3
+
+# Install python-dotenv
+$ pip install python-dotenv
+
+# Install py-solc-x
+$ pip install py-solc-x
+```
+
+Remember that each new terminal session requires you to reactivate your virtualenv, like: 
+```bash
+$ source ~/.venv-py3/bin/activate
+```
+
+3. **Create and complete `.env` file from `.env.example`**
+
+4. **Run script**
+```bash
+python scripts/test.py
+```

tools/web3py-example/contract/Greeter.sol

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+//SPDX-License-Identifier: Unlicense
+pragma solidity >0.5.0;
+
+contract Greeter {
+    string public greeting;
+
+    constructor() public {
+        greeting = 'Hello';
+    }
+
+    function setGreeting(string memory _greeting) public {
+        greeting = _greeting;
+    }
+
+    function greet() view public returns (string memory) {
+        return greeting;
+    }
+}

tools/web3py-example/scripts/test.py

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+#
+# Hedera JSON RPC Relay - Web3py Example
+#
+# Copyright (C) 2022-2024 Hedera Hashgraph, LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import os
+import unittest
+from dotenv import load_dotenv
+from web3 import Web3
+from solcx import install_solc, compile_source
+
+def setup_environment():
+    # install latest solc
+    install_solc(version='latest')
+
+    # load values from our .env file
+    load_dotenv()
+    OPERATOR_PRIVATE_KEY = os.getenv('OPERATOR_PRIVATE_KEY')
+    RELAY_ENDPOINT = os.getenv('RELAY_ENDPOINT')
+
+    # connect to chain
+    w3 = Web3(Web3.HTTPProvider(RELAY_ENDPOINT))
+
+    # get account from pk
+    acc = w3.eth.account.from_key(OPERATOR_PRIVATE_KEY)
+
+    return w3, acc
+
+
+def get_balance(w3, acc):
+    balance = w3.eth.get_balance(acc.address)
+    return balance
+
+
+def deploy_contract(w3, acc):
+    # read contract from file
+    with open('contract/Greeter.sol', 'r') as f:
+        source = f.read()
+
+    # compile our Greeter contract
+    compiled_sol = compile_source(source, output_values=['abi', 'bin'])
+
+    # retrieve the contract interface
+    contract_id, contract_interface = compiled_sol.popitem()
+
+    bytecode = contract_interface['bin']
+    abi = contract_interface['abi']
+
+    # create web3.py contract instance
+    Greeter = w3.eth.contract(abi=abi, bytecode=bytecode)
+
+    # build transaction
+    unsent_tx_hash = Greeter.constructor().build_transaction({
+        "from": acc.address,
+        "nonce": w3.eth.get_transaction_count(acc.address),
+    })
+
+    # sign transaction
+    signed_tx = w3.eth.account.sign_transaction(unsent_tx_hash, private_key=acc.key)
+
+    # send transaction
+    tx_hash = w3.eth.send_raw_transaction(signed_tx.rawTransaction)
+    tx_receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
+
+    # create instance of deployed contract
+    greeter = w3.eth.contract(
+        address=tx_receipt.contractAddress,
+        abi=abi
+    )
+
+    return greeter, tx_receipt.contractAddress
+
+
+def contract_view_call(greeter):
+    greeting = greeter.functions.greet().call()
+    return greeting
+
+
+def contract_call(w3, acc, greeter):
+    # build contract call transaction
+    unsent_call_tx_hash = greeter.functions.setGreeting('Hello2').build_transaction({
+        "from": acc.address,
+        "nonce": w3.eth.get_transaction_count(acc.address),
+    })
+
+    # sign transaction
+    signed_call_tx = w3.eth.account.sign_transaction(unsent_call_tx_hash, private_key=acc.key)
+
+    # send transaction
+    call_tx_hash = w3.eth.send_raw_transaction(signed_call_tx.rawTransaction)
+    w3.eth.wait_for_transaction_receipt(call_tx_hash)
+
+    # Verify the greeting has been updated
+    new_greeting = greeter.functions.greet().call()
+    return new_greeting
+
+
+class TestGreeterContract(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        cls.w3, cls.acc = setup_environment()
+        cls.greeter, cls.contract_address = deploy_contract(cls.w3, cls.acc)
+
+    def test_get_balance(self):
+        balance = get_balance(self.w3, self.acc)
+        self.assertIsInstance(balance, int, "Account balance is an integer")
+
+    def test_deploy_contract(self):
+        self.assertTrue(self.contract_address.startswith('0x'), "Contract address starts with '0x'")
+
+    def test_call_view(self):
+        greeting = contract_view_call(self.greeter)
+        self.assertEqual(greeting, 'Hello', "Initial greeting matches expected value")
+
+    def test_contract_call(self):
+        new_greeting = contract_call(self.w3, self.acc, self.greeter)
+        self.assertEqual(new_greeting, 'Hello2', "Updated greeting matches expected value")
+
+        final_greeting = contract_view_call(self.greeter)
+        self.assertEqual(final_greeting, 'Hello2', "Final greeting matches expected value after update")
+
+
+if __name__ == "__main__":
+    unittest.main()