doc: Unify Python optional module and test dependency documentation

The current documentation combine two different approaches: OS-specific
notes and OS-agnostic Python-specific notes. This has multiple issues:
1. OS-specific notes miss the `pycapnp` module.
2. `python3-zmq` is a package name in some Linux distros, rather than a
Unix-wide convention.
3. Installing `pyzmq` from PyPI works in general, not only on macOS.

As the functional test framework is Python-based, this consolidates
the documentation in Python-focused notes fixing the mentioned issues.

Author: hebasto

doc/build-freebsd.md

@@ -70,13 +70,8 @@ pkg install libzmq4 pkgconf
 ```
 
 #### Test Suite Dependencies
-There is an included test suite that is useful for testing code changes when developing.
-To run the test suite (recommended), you will need to have Python 3 installed:
 
-```bash
-pkg install python3 databases/py-sqlite3 net/py-pyzmq lsof
-```
----
+See [`test/README.md`](/test/README.md#dependencies-and-prerequisites).
 
 ## Building Bitcoin Core
 

doc/build-netbsd.md

@@ -73,19 +73,7 @@ pkgin install zeromq pkgconf
 
 #### Test Suite Dependencies
 
-There is an included test suite that is useful for testing code changes when developing.
-To run the test suite (recommended), you will need to have Python 3 installed:
-
-```bash
-pkgin install python313 py313-zmq lsof
-```
-
-When the `lsof` binary package was built for a different point release, it might be necessary to force its installation as follows:
-
-```bash
-echo "CHECK_OSABI=no" >> /etc/pkg_install.conf
-pkgin install lsof
-```
+See [`test/README.md`](/test/README.md#dependencies-and-prerequisites).
 
 ## Building Bitcoin Core
 

doc/build-openbsd.md

@@ -70,12 +70,8 @@ pkg_add zeromq
 ```
 
 #### Test Suite Dependencies
-There is an included test suite that is useful for testing code changes when developing.
-To run the test suite (recommended), you will need to have Python 3 installed:
 
-```bash
-pkg_add python py3-zmq  # Select the newest version of the python package if necessary.
-```
+See [`test/README.md`](/test/README.md#dependencies-and-prerequisites).
 
 ## Building Bitcoin Core
 

doc/build-osx.md

@@ -121,12 +121,7 @@ For more information on ZMQ, see: [zmq.md](zmq.md)
 
 #### Test Suite Dependencies
 
-There is an included test suite that is useful for testing code changes when developing.
-To run the test suite (recommended), you will need to have Python 3 installed:
-
-``` bash
-brew install python
-```
+See [`test/README.md`](/test/README.md#dependencies-and-prerequisites).
 
 ---
 

doc/build-unix.md

@@ -88,3 +88,7 @@ be compiled in disable-wallet mode with:
 In this case there is no dependency on SQLite.
 
 Mining is also possible in disable-wallet mode using the `getblocktemplate` RPC call.
+
+### Test Suite Dependencies
+
+See [`test/README.md`](/test/README.md#dependencies-and-prerequisites).

doc/build-windows-msvc.md

@@ -32,15 +32,9 @@ This installs:
 After installation, the commands in this guide should be executed in "Developer PowerShell for VS" or "Developer Command Prompt for VS".
 The former is assumed hereinafter.
 
-#### Python
+#### Test Suite Dependencies
 
-Python is required for running the test suite.
-
-To install Python, run:
-
-```powershell
-winget install python3
-```
+See [`test/README.md`](/test/README.md#dependencies-and-prerequisites).
 
 ### 2. Clone Bitcoin Repository
 

test/README.md

@@ -29,27 +29,24 @@ See [/doc/fuzzing.md](/doc/fuzzing.md)
 
 ### Dependencies and prerequisites
 
-The ZMQ functional test requires a python ZMQ library. To install it:
+The functional tests require Python to be installed. For the minimum required Python version, refer to [Dependencies](/doc/dependencies.md#build-1).
 
-- on Unix, run `sudo apt-get install python3-zmq`
-- on mac OS, run `pip3 install pyzmq`
+#### Optional dependencies
 
-The IPC functional test requires a python IPC library. `pip3 install pycapnp` may work, but if not, install it from source:
+Some tests require optional dependencies: Python modules and system utilities.
+They can be installed with any suitable tool, like the system package manager, `pip` in a virtual environment, or `uv`.
 
-```sh
-git clone -b v2.2.1 https://github.com/capnproto/pycapnp
-pip3 install ./pycapnp
-```
-
-If that does not work, try adding `-C force-bundled-libcapnp=True` to the `pip` command.
-Depending on the system, it may be necessary to install and run in a venv:
+If a dependency is not installed, the tests will be skipped rather than failed.
 
-```sh
-python -m venv venv
-git clone -b v2.2.1 https://github.com/capnproto/pycapnp
-venv/bin/pip3 install ./pycapnp -C force-bundled-libcapnp=True
-venv/bin/python3 build/test/functional/interface_ipc.py
-```
+| Package manager | Python | sqlite3 | zmq | capnp | lsof |
+| :--- | :--- | :--- | :--- | :--- | :--- |
+| **pip** | n/a | n/a | `pyzmq` | `pycapnp` | n/a |
+| **Debian/Ubuntu**<br>(`apt`) | `python3` | n/a | `python3-zmq` | n/a | n/a |
+| **macOS**<br>(`brew`) | `python3` | n/a | n/a | n/a | n/a |
+| **Windows**<br>(`winget`) | `python3` | n/a | n/a | n/a | n/a |
+| **FreeBSD**<br>(`pkg`) | `python3` | `databases/py-sqlite3` | `net/py-pyzmq` | n/a | `lsof` |
+| **NetBSD**<br>(`pkgin`) | `python313` | n/a | `py313-zmq` | n/a | `lsof` |
+| **OpenBSD**<br>(`pkg_add`) | `python` | n/a | `py3-zmq` | n/a | n/a |
 
 #### UTF-8 mode