Testing Bitcoin Core source code? What's the recommended way to start testing the Bitcoin Core source code.

Thanks in advance,
Jim
What's the recommended way to start testing the Bitcoin Core source code?
testing for verification of bug fixes

See https://github.com/bitcoin/bitcoin/blob/master/src/test/README.md which says:

To run the bitcoind tests manually, launch src/test/test_bitcoin. To recompile after a test file was modified, run make and then run the test again. If you modify a non-test file, use make -C src/test to recompile only what's needed to run the bitcoind tests.
To add more bitcoind tests, add BOOST_AUTO_TEST_CASE functions to the existing .cpp files in the test/ directory or add new .cpp files that implement new BOOST_AUTO_TEST_SUITE sections.
To run the bitcoin-qt tests manually, launch src/qt/test/test_bitcoin-qt
To add more bitcoin-qt tests, add them to the src/qt/test/ directory and the src/qt/test/test_main.cpp file.

There is more.