contrib: Add external RPC code generator with unit tests #32140

1. 
   EniRox001 commented at 7:16 pm on March 25, 2025: none

   Description

   This pull request introduces an external tool for generating RPC client code based on the Bitcoin Core RPC schema. The tool is implemented in Python using Jinja2 templates and can generate code for both C++ and Python clients. In addition, unit tests have been added to verify that the generator produces the expected output given a sample schema.

   Changes Included

   • contrib/codegen/generate_client.py
     A script that retrieves the latest RPC schema (via bitcoin-cli) and renders language- specific templates.
   • contrib/codegen/templates/
     • cpp_client.jinja2 – Template for generating a C++ RPC client header.
     • python_client.jinja2 – Template for generating a Python RPC client.
   • contrib/codegen/tests/test_generate_client.py
     Unit tests to ensure the code generator works as expected for both C++ and Python output.

   Rationale

   This tool provides a convenient way for developers to automatically update external client libraries when the RPC schema changes. It improves maintainability by reducing manual effort and potential errors. As a non-core developer utility, it is placed under the contrib/ directory to keep it separate from the core runtime.

   Testing and Verification

   • The generated client code for both C++ and Python has been compiled (for C++) and run in a test harness.
   • Unit tests verify that, given a sample schema, the output contains the expected method declarations and syntax.
   • The tool automatically retrieves the latest schema using the bitcoin-cli schema RPC.

   Please see the accompanying README in contrib/codegen/ for detailed usage instructions.

2. Add `schema` RPC 9d90e50d19
3. Add external code generator for RPC clients

   Introduce generate_client.py to generate client code from the Bitcoin
   Core RPC schema. This tool enables developers to easily update and
   maintain client libraries in various languages by automatically
   reflecting changes in the RPC interface.

   02c68c3db1
4. Add Python client template using Jinja2

   Include the python_client.jinja2 template in the code generator. This
   template defines the structure for the generated Python RPC client and
   integrates with generate_client.py to reflect RPC schema changes
   automatically.

   7a4108c30e
5. Add C++ client test harness and template

   Introduce main.cpp as a test program to verify the generated C++
   RPC client template. This commit adds a minimal harness that instantiates
   BitcoinRPCClient, calls getblockchaininfo, and prints the result. The
   template and test program help ensure that our C++ client code integrates
   correctly with libcurl and JsonCpp, aiding further development and testing.

   3be8d37446
6. 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.

   aaba9b27d4
7. 
   DrahtBot commented at 7:16 pm on March 25, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32140.

   Reviews

   See the guideline for information on the review process. A summary of reviews will appear here.

8. DrahtBot added the label Scripts and tools on Mar 25, 2025
9. DrahtBot added the label CI failed on Mar 25, 2025
10. 
    DrahtBot commented at 7:29 pm on March 25, 2025: contributor

    🚧 At least one of the CI tasks failed. Debug: https://github.com/bitcoin/bitcoin/runs/39395957729

    Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

    • Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

    • A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

    • An intermittent issue.

    Leave a comment here, if you need help tracking down a confusing failure.

11. 
    laanwj commented at 4:05 am on March 26, 2025: member

    /schema.json probably wasn’t intended to be in this PR.
12. Remove schema.json file

    Remove the static schema.json file since the generator now retrieves the
    latest schema dynamically via bitcoin-cli. This change prevents stale
    data and reduces repository clutter.

    44fbc9d83d
13. 
    EniRox001 commented at 11:04 am on March 26, 2025: none

    /schema.json probably wasn’t intended to be in this PR.

    Yes, redundant now that latest schema is retrieved each time, pushed the change

Contributors
EniRox001 DrahtBot laanwj

Labels
Scripts and tools CI failed