A python script that downloads nuget and installs FAKE and Xunit test runner. It also creates a script for running tests.

setup_fake.py

#!python

import os
import subprocess as sp

__build = \
'''
// include Fake lib
#r @"tools/FAKE/tools/FakeLib.dll"
open Fake
open Fake.Testing
open Fake.NuGet.Install

let testDir = "{}.Tests/bin/Debug" 

let inline getBuildOption name = match environVar name with
                                 | null -> None
                                 | s -> Some s  

let runTests() =
    !! (testDir + "/*.Tests.dll")
        |> xUnit2 (fun p -> {{ p with 
                                 ToolPath = findToolInSubPath "xunit.console.x86.exe" (currentDirectory @@ "tools" @@ "xUnit")
                                 Method = getBuildOption "method"
                            }} )
        
// Default target
Target "RunTests" (fun _ ->
    runTests()
)

// continuous test runner
Target "Watch" (fun _->
    use watcher = !! (testDir + "/*.dll") |> WatchChanges (fun changes ->
        tracefn "%A" changes
        runTests()
    )

    System.Console.ReadLine() |> ignore

    watcher.Dispose()
)

// install test runner
Target "Setup" (fun _ ->
    NugetInstall (fun p -> {{ p with
                                 ExcludeVersion = true
                                 OutputDirectory = "tools"
                           }} ) "xunit.runner.console"
)

// start build
RunTargetOrDefault "RunTests"
'''


def get_nuget():
    path = r'c:/bin/nuget.exe'
    if os.path.exists(path):
        print('using global nuget...')
        return path

    path = r'./tools/nuget.exe' 
    if os.path.exists(path):
        print('using local nuget...')
        return path

    if not os.path.exists('./tools'):
        print('creating tools directory')
        os.makedirs('./tools')

    cmd = r'powershell -Command "Invoke-WebRequest https://dist.nuget.org/win-x86-commandline/latest/nuget.exe -OutFile .\tools\nuget.exe"'
    print('downloading nuget...')
    output = sp.check_output(cmd)
    print(output)

    return path


def install_fake(nuget):
    print('installing fake...')
    output = sp.check_output('"{}" "Install" "FAKE" "-OutputDirectory" "tools" "-ExcludeVersion"'.format(nuget))
    print(output)

def install_xunit():
    print('installing xunit runner...')
    output = sp.check_output('./tools/FAKE/tools/fake.exe setup')
    print(output)

def generate_build(name):
    if not os.path.exists('build.fsx'):
        print('creating build.fsx...')
        with open('build.fsx', 'wt') as f:
            f.write(__build.format(name))

    else:
        print('build.fsx already exists!')

if __name__ == '__main__':
    nuget = get_nuget()
    install_fake(nuget)
    
    name = os.path.basename(os.getcwd())
    print('project name: {}'.format(name))

    generate_build(name)
    install_xunit()