def test_hello_world(cli):
    cli.src('tox.ini', r"""
    [tox]
    envlist = py27,py36

    [testenv]
    deps = pytest
    commands = pytest
    """)

    # setup.py in the same directory
    cli.src('setup.py', r"""
    from setuptools import setup

    setup(
        name='hello-world',
        packages=['hello'],
    )
    """)

    # production code
    cli.src('hello/__init__.py')
    cli.src('hello/hello.py', r"""
    def say_hello(who='World'):
        return 'Hello, %s!' % who
    """)

    # test code; at least one test
    cli.src('tests/test_hello.py', r"""
    from hello import hello

    def test_hello():
        assert hello.say_hello() == 'Hello, World!'
        assert hello.say_hello('pytest') == 'Hello, pytest!'
    """)

    r = cli.run('tox')
    assert 'py27: commands succeeded' in r.out
    assert 'py36: commands succeeded' in r.out

    # directories .tox/ and *.egg-info/ got created
    assert cli.exists('.tox/')
    assert cli.exists('hello_world.egg-info/')

def test_interpreter_not_found(cli):
    cli.src('tox.ini', r"""
    [tox]
    envlist = py37

    [testenv]
    deps = pytest
    commands = pytest
    """)

    cli.src('setup.py', r"""
    from setuptools import setup

    setup(
        name='proj',
    )
    """)

    r = cli.run_err('tox')
    assert 'ERROR:   py37: InterpreterNotFound: python3.7' in r.out


@@ -1009,27 +1009,303 @@
 t_in
-terpreter_not_found
+voke_tox__no_setuppy__error(cli):%0A    cli.src('tox.ini', r%22%22%22%0A    %5Btox%5D%0A    envlist = py27,py36%0A%0A    %5Btestenv%5D%0A    deps = pytest%0A    commands = pytest%0A    %22%22%22)%0A%0A    r = cli.run_err('tox')%0A    assert 'ERROR: No setup.py file found.' in r.out%0A%0Adef test_invoke_tox__interpreter_not_installed__error
 (cli

setup.py is manadatory