Add tests for generate_client.py and Jinja templates

Introduce unit tests for the generate_client.py script to verify
correct code generation for both C++ and Python clients. These tests
ensure that the script produces the expected output based on a sample
schema, enhancing the reliability of the code generation process.

contrib/codegen/test.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+
+import os
+import tempfile
+import json
+import unittest
+from subprocess import run, PIPE
+from generate_client import load_schema, generate_client, sanitize_argument_names
+
+class TestGenerateClient(unittest.TestCase):
+
+    def setUp(self):
+        # Create a temporary directory for output files
+        self.temp_dir = tempfile.TemporaryDirectory()
+        # Create a sample schema dictionary
+        self.sample_schema = {
+            "rpcs": {
+                "getblockchaininfo": {
+                    "description": "Returns blockchain info.",
+                    "argument_names": []
+                },
+                "addconnection": {
+                    "description": "Opens an outbound connection.",
+                    "argument_names": ["address", "connection_type", "v2transport"]
+                }
+            }
+        }
+        # Sanitize the sample schema if necessary
+        self.sample_schema["rpcs"] = sanitize_argument_names(self.sample_schema["rpcs"])
+
+    def tearDown(self):
+        # Clean up temporary directory
+        self.temp_dir.cleanup()
+
+    def test_generate_cpp_client(self):
+        # Test generating C++ code
+        output_dir = self.temp_dir.name
+        generate_client(self.sample_schema, "cpp", output_dir)
+        generated_file = os.path.join(output_dir, "bitcoin_rpc_client.cpp")
+        self.assertTrue(os.path.exists(generated_file))
+        with open(generated_file, "r") as f:
+            content = f.read()
+        # Check that key parts appear in the generated file
+        self.assertIn("class BitcoinRPCClient", content)
+        self.assertIn("std::string getblockchaininfo()", content)
+        self.assertIn("std::string addconnection(", content)
+
+    def test_generate_python_client(self):
+        # Test generating Python code
+        output_dir = self.temp_dir.name
+        generate_client(self.sample_schema, "python", output_dir)
+        generated_file = os.path.join(output_dir, "bitcoin_rpc_client.py")
+        self.assertTrue(os.path.exists(generated_file))
+        with open(generated_file, "r") as f:
+            content = f.read()
+        # Check that key parts appear in the generated file
+        self.assertIn("class BitcoinRPCClient", content)
+        self.assertIn("def getblockchaininfo(self):", content)
+        self.assertIn("def addconnection(self, address, connection_type, v2transport):", content)
+
+if __name__ == '__main__':
+    unittest.main()