Ensure the dependencies are installed:

    Linux: sudo apt-get install build-essential libtool autotools-dev automake pkg-config bsdmainutils python3 libssl-dev libevent-dev libboost-system-dev libboost-filesystem-dev libboost-chrono-dev libboost-test-dev libboost-thread-dev libminiupnpc-dev libzmq3-dev libqt5gui5 libqt5core5a libqt5dbus5 qttools5-dev qttools5-dev-tools libprotobuf-dev protobuf-compiler git ccache

    macOS (with command line tools and Homebrew already installed): brew install automake berkeley-db4 libtool boost miniupnpc openssl pkg-config protobuf python qt libevent qrencode ccache

Download the BitcoinNickel source files by git cloning the repository:
    git clone https://github.com/bitcoinNickel/bitcoinnickel.git

Install Berkeley DB (BDB) v4.8, a backward-compatible version needed for the wallet, using the script in /contrib:
    Enter your local copy of the BitcoinNickel repository: cd bitcoinnickel
    Now that you are in the root of the bitcoinnickel repository, run ./contrib/install_db4.sh `pwd`
    Take note of the instructions displayed in the terminal at the end of the BDB installation process:

  db4 build complete.

  When compiling bitcoinnickeld, run `./configure` in the following way:

  export BDB_PREFIX='<PATH-TO>/db4'

  ./configure BDB_LIBS="-L${BDB_PREFIX}/lib -ldb_cxx-4.8" BDB_CFLAGS="-I${BDB_PREFIX}/include" ...

Compile from a tagged release branch instead of master, unless you want to test the bleeding edge:
    git tag -n | sort -V to see tags and descriptions ordered by most recent last
    git checkout <TAG> to use a tagged release, for example: git checkout v0.0.0.1

Compile BitcoinNickel from source:
    ./autogen.sh
    export BDB_PREFIX='<PATH-TO>/db4' (you can use the output from the BDB build above)
    ./configure BDB_LIBS="-L${BDB_PREFIX}/lib -ldb_cxx-4.8" BDB_CFLAGS="-I${BDB_PREFIX}/include"
    make, or if you have multiple threads on your machine, you can tell make to use all of them and reduce compile time significantly with
    make -j"$(($(nproc)+1))" on Linux, or
    make -j"$(($(sysctl -n hw.physicalcpu)+1))" on macOS

You can run ./configure --help to see the various configuration options.

If you build frequently from source (e.g. for testing pull requests), as long as you don't need to change the configuration options you can skip directly to the make step for subsequent builds.

Be sure to use ccache to speed up your builds. You can also gain time by building only what you need. See the BitcoinNickel Core productivity notes for more.

Run the unit tests:
    make check, or
    make -j"$(($(nproc)+1))" check to use multithreading on Linux, or
    make -j"$(($(sysctl -n hw.physicalcpu)+1))" check on macOS

Run the functional tests. From the repository root:
    test/functional/test_runner.py to run the standard test suite
    test/functional/test_runner.py --extended to run the extended test suite
    test/functional/test_runner.py --help to see the various options for running tests