No pyproject.toml, nothing installed:
  installed:
    # empty
  except: FileNotFoundError

Nothing installed yet:
  installed:
    # empty
  pyproject.toml: |
    # empty
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
  except: FileNotFoundError

Insufficient version of setuptools:
  installed:
    setuptools: 5
    wheel: 1
    toml: 1
  pyproject.toml: |
    # empty
  setup.py: |
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
  result: 0

No pyproject.toml, empty setup.py:
  installed:
    setuptools: 50
    wheel: 1
  include_runtime: false
  setup.py: |
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
  result: 0

Default build system, empty setup.py:
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  include_runtime: false
  pyproject.toml: |
    # empty
  setup.py: |
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
  result: 0

pyproject.toml with build-backend and setup.py:
  generate_extras: true
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  setup.py: |
    # empty
  pyproject.toml: |
    [build-system]
    requires = [
        "foo",
    ]
    build-backend = "foo.build"
  expected: |
    python3dist(foo)
  result: 0

Erroring setup.py:
  installed:
    setuptools: 50
    wheel: 1
  setup.py: |
    exit(77)
  result: 77

Bad character in version:
  installed:
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["pkg == 0.$.^.*"]
  except: ValueError

Single value version with unsupported compatible operator:
  installed:
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["pkg ~= 42", "foo"]
    build-backend = "foo.build"
  except: ValueError

Asterisk in version with unsupported compatible operator:
  installed:
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["pkg ~= 0.1.*", "foo"]
    build-backend = "foo.build"
  except: ValueError

Local path as requirement:
  installed:
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["./pkg-1.2.3.tar.gz", "foo"]
    build-backend = "foo.build"
  except: ValueError

Pip's egg=pkgName requirement not in requirements file:
  installed:
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["git+https://github.com/monty/spam.git@master#egg=spam", "foo"]
    build-backend = "foo.build"
  except: ValueError

URL without egg fragment as requirement:
  installed:
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["git+https://github.com/pkg-dev/pkg.git@96dbe5e3", "foo"]
    build-backend = "foo.build"
  except: ValueError

Build system dependencies in pyproject.toml with extras:
  generate_extras: true
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = [
        "foo",
        "bar[bAz] > 5",
        "ne!=1",
        "ge>=1.2.0",
        "le <= 1.2.3",
        "lt < 1.2.3.4      ",
        "    gt > 1.2.3.4.5",
        "compatible ~= 0.4.0",
        "equal == 0.5.0",
        "arbitrary_equal === 0.6.0",
        "asterisk_equal == 0.6.*",
        "appdirs@https://github.com/ActiveState/appdirs/archive/8eacfa312d77aba28d483fbfb6f6fc54099622be.zip",
        "multi[Extras1,Extras2] == 6.0",
        "combo >2, <5, != 3.0.0",
        "py2 ; python_version < '2.7'",
        "py3 ; python_version > '3.0'",
    ]
    build-backend = "foo.build"
  expected: |
    python3dist(foo)
    python3dist(bar) > 5.0
    python3dist(bar[baz]) > 5.0
    (python3dist(ne) < 1 or python3dist(ne) > 1)
    python3dist(ge) >= 1.2
    python3dist(le) <= 1.2.3
    python3dist(lt) < 1.2.3.4~~
    python3dist(gt) > 1.2.3.4.5.0
    (python3dist(compatible) >= 0.4 with python3dist(compatible) < 0.5)
    python3dist(equal) = 0.5
    python3dist(arbitrary-equal) = 0.6
    (python3dist(asterisk-equal) >= 0.6 with python3dist(asterisk-equal) < 0.7)
    python3dist(appdirs)
    python3dist(multi) = 6
    python3dist(multi[extras1]) = 6
    python3dist(multi[extras2]) = 6
    ((python3dist(combo) < 3 or python3dist(combo) > 3) with python3dist(combo) < 5~~ with python3dist(combo) > 2.0)
    python3dist(py3)
  stderr_contains: "WARNING: Simplifying 'appdirs@https://github.com/ActiveState/appdirs/archive/8eacfa312d77aba28d483fbfb6f6fc54099622be.zip' to 'appdirs'."
  result: 0

Build system dependencies in pyproject.toml without extras:
  generate_extras: false
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = [
        "bar[Baz] > 5",
        "multi[extras1,extras2] == 6.0",
    ]
    build-backend = "foo.build"
  expected: |
    python3dist(bar) > 5.0
    python3dist(multi) = 6
  result: 0

Default build system, build dependencies in setup.py:
  installed:
    setuptools: 50
    wheel: 1
  include_runtime: false
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
        setup_requires=['foo', 'bar!=2', 'baz~=1.1.1'],
        install_requires=['inst'],
    )
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
    python3dist(foo)
    (python3dist(bar) < 2 or python3dist(bar) > 2)
    (python3dist(baz) >= 1.1.1 with python3dist(baz) < 1.2)
  result: 0

Default build system, run dependencies in setup.py:
  installed:
    setuptools: 50
    wheel: 1
    pyyaml: 1
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
        setup_requires=['pyyaml'],  # nb. setuptools will try to install this
        install_requires=['inst > 1', 'inst2 < 3'],
    )
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
    python3dist(pyyaml)
    python3dist(inst) > 1.0
    python3dist(inst2) < 3~~
  result: 0

Run dependencies with extras (not selected):
  installed:
    setuptools: 50
    wheel: 1
    pyyaml: 1
  setup.py: &pytest_setup_py |
        # slightly abriged copy of pytest's setup.py
        from setuptools import setup

        INSTALL_REQUIRES = [
            "py>=1.5.0",
            "six>=1.10.0",
            "setuptools",
            "attrs>=17.4.0",
            'more-itertools>=4.0.0,<6.0.0;python_version<="2.7"',
            'more-itertools>=4.0.0;python_version>"2.7"',
            "atomicwrites>=1.0",
            'funcsigs>=1.0;python_version<"3.0"',
            'pathlib2>=2.2.0;python_version<"3.6"',
            'colorama;sys_platform=="win32"',
            "pluggy>=0.11",
        ]

        def main():
            setup(
                name = "pytest",
                version = "6.6.6",
                setup_requires=["setuptools>=40.0"],
                # fmt: off
                extras_require={
                    "testing": [
                        "argcomplete",
                        "hypothesis>=3.56",
                        "nose",
                        "requests",
                        "mock;python_version=='2.7'",
                    ],
                },
                # fmt: on
                install_requires=INSTALL_REQUIRES,
            )

        if __name__ == "__main__":
            main()
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
    python3dist(setuptools) >= 40
    python3dist(py) >= 1.5
    python3dist(six) >= 1.10
    python3dist(setuptools)
    python3dist(attrs) >= 17.4
    python3dist(atomicwrites) >= 1
    python3dist(pluggy) >= 0.11
    python3dist(more-itertools) >= 4
  result: 0

Run dependencies with extras (selected):
  installed:
    setuptools: 50
    wheel: 1
    pyyaml: 1
  include_runtime: true
  extras:
    - testing
  setup.py: *pytest_setup_py
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
    python3dist(setuptools) >= 40
    python3dist(py) >= 1.5
    python3dist(six) >= 1.10
    python3dist(setuptools)
    python3dist(attrs) >= 17.4
    python3dist(atomicwrites) >= 1
    python3dist(pluggy) >= 0.11
    python3dist(more-itertools) >= 4
    python3dist(argcomplete)
    python3dist(hypothesis) >= 3.56
    python3dist(nose)
    python3dist(requests)
  result: 0

Run dependencies with multiple extras:
  installed:
    setuptools: 50
    wheel: 1
    pyyaml: 1
  include_runtime: true
  generate_extras: true
  extras:
    - testing,more-testing
    - even-more-testing , cool-feature
  setup.py: |
    from setuptools import setup
    setup(
        extras_require={
            'testing': ['dep1'],
            'more-testing': ['dep2'],
            'even-more-testing': ['dep3'],
            'cool-feature': ['dep4[FOO,BAR]'],
        },
    )
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
    python3dist(dep4)
    python3dist(dep4[bar])
    python3dist(dep4[foo])
    python3dist(dep3)
    python3dist(dep2)
    python3dist(dep1)
  result: 0

Run dependencies with extras and build wheel option:
  installed:
    setuptools: 50
    wheel: 1
    pyyaml: 1
  include_runtime: true
  build_wheel: true
  extras:
    - testing
  setup.py: *pytest_setup_py
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
    python3dist(setuptools) >= 40
    python3dist(py) >= 1.5
    python3dist(six) >= 1.10
    python3dist(setuptools)
    python3dist(attrs) >= 17.4
    python3dist(atomicwrites) >= 1
    python3dist(pluggy) >= 0.11
    python3dist(more-itertools) >= 4
    python3dist(argcomplete)
    python3dist(hypothesis) >= 3.56
    python3dist(nose)
    python3dist(requests)
  result: 0
  stderr_contains: "Reading metadata from {wheeldir}/pytest-6.6.6-py3-none-any.whl"

tox dependencies:
  installed:
    setuptools: 50
    wheel: 1
    tox: 3.5.3
    tox-current-env: 0.0.6
  toxenv:
    - py3
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
        install_requires=['inst'],
    )
  tox.ini: |
    [tox]
    envlist = py36,py37,py38
    [testenv]
    deps =
        toxdep1
        toxdep2
    commands =
        true
  expected:
    - |  # tox 3
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(toxdep1)
      python3dist(toxdep2)
      python3dist(inst)
    - |  # tox 4
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(tox)
      python3dist(toxdep1)
      python3dist(toxdep2)
      python3dist(inst)
  result: 0

tox extras:
  installed:
    setuptools: 50
    wheel: 1
    tox: 3.5.3
    tox-current-env: 0.0.6
  generate_extras: true
  toxenv:
    - py3
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
        install_requires=['inst'],
        extras_require={
            'extra1':  ['dep11 > 11', 'dep12'],
            'extra2': ['dep21', 'dep22', 'dep23', 'extra_dep[EXTRA_DEP]'],
            'nope': ['nopedep'],
        }
    )
  tox.ini: |
    [tox]
    envlist = py36,py37,py38
    [testenv]
    deps =
        toxdep
    extras =
        extra2
        extra1
    commands =
        true
  expected:
    - |  # tox 3
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(toxdep)
      python3dist(inst)
      python3dist(dep11) > 11.0
      python3dist(dep12)
      python3dist(dep21)
      python3dist(dep22)
      python3dist(dep23)
      python3dist(extra-dep)
      python3dist(extra-dep[extra_dep])
    - |  # tox 4
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(tox)
      python3dist(toxdep)
      python3dist(inst)
      python3dist(dep11) > 11.0
      python3dist(dep12)
      python3dist(dep21)
      python3dist(dep22)
      python3dist(dep23)
      python3dist(extra-dep)
      python3dist(extra-dep[extra_dep])
  result: 0

tox provision unsatisfied:
  installed:
    setuptools: 50
    wheel: 1
    tox: 3.5.3
    tox-current-env: 0.0.6
  toxenv:
    - py3
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
        install_requires=['inst'],
    )
  tox.ini: |
    [tox]
    minversion = 3.999
    requires =
        setuptools > 40
        wheel > 2
    [testenv]
    deps =
        toxdep1
        toxdep2
  expected:
    - |  # tox 3
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(tox) >= 3.999
      python3dist(setuptools) > 40.0
      python3dist(wheel) > 2.0
    - |  # tox 4
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(tox) >= 3.999
      python3dist(setuptools) > 40.0
      python3dist(wheel) > 2.0
      python3dist(tox) >= 3.999
  result: 0

tox provision satisfied:
  installed:
    setuptools: 50
    wheel: 1
    tox: 3.5.3
    tox-current-env: 0.0.6
  toxenv:
    - py3
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
        install_requires=['inst'],
    )
  tox.ini: |
    [tox]
    minversion = 3.5
    requires =
        setuptools > 40
    [testenv]
    deps =
        toxdep1
        toxdep2
  expected:
    - |  # tox 3
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(tox) >= 3.5
      python3dist(setuptools) > 40.0
      python3dist(toxdep1)
      python3dist(toxdep2)
      python3dist(inst)
    - |  # tox 4
      python3dist(setuptools) >= 40.8
      python3dist(wheel)
      python3dist(wheel)
      python3dist(tox-current-env) >= 0.0.6
      python3dist(setuptools) > 40.0
      python3dist(tox) >= 3.5
      python3dist(toxdep1)
      python3dist(toxdep2)
      python3dist(inst)
  result: 0

Default build system, unmet deps in requirements file:
  installed:
    setuptools: 50
    wheel: 1
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
    )
  requirements.txt: |
    lxml
    ncclient
    cryptography
    paramiko
    SQLAlchemy
  requirement_files:
    - requirements.txt
  expected: |
    python3dist(lxml)
    python3dist(ncclient)
    python3dist(cryptography)
    python3dist(paramiko)
    python3dist(sqlalchemy)
  result: 0

Default build system, met deps in requirements file:
  installed:
    setuptools: 50
    wheel: 1
    lxml: 3.9
    ncclient: 1
    cryptography: 2
    paramiko: 1
    SQLAlchemy: 1.0.90
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
    )
  requirements.txt: |
    lxml!=3.7.0,>=2.3    # OF-Config
    ncclient  # OF-Config
    cryptography!=1.5.2  # Required by paramiko
    paramiko  # NETCONF, BGP speaker (SSH console)
    SQLAlchemy>=1.0.10,<1.1.0  # Zebra protocol service
  requirement_files:
    - requirements.txt
  expected: |
    ((python3dist(lxml) < 3.7 or python3dist(lxml) > 3.7) with python3dist(lxml) >= 2.3)
    python3dist(ncclient)
    (python3dist(cryptography) < 1.5.2 or python3dist(cryptography) > 1.5.2)
    python3dist(paramiko)
    (python3dist(sqlalchemy) < 1.1~~ with python3dist(sqlalchemy) >= 1.0.10)
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
  result: 0

With pyproject.toml, requirements file and with -N option:
  use_build_system: false
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
    lxml: 3.9
    ncclient: 1
    cryptography: 2
    paramiko: 1
    SQLAlchemy: 1.0.90
  pyproject.toml: |
    [build-system]
    requires = [
        "foo",
    ]
    build-backend = "foo.build"
  requirements.txt: |
    lxml
    ncclient
    cryptography
    paramiko
    SQLAlchemy
    git+https://github.com/monty/spam.git@master#egg=spam
  requirement_files:
    - requirements.txt
  expected: |
    python3dist(lxml)
    python3dist(ncclient)
    python3dist(cryptography)
    python3dist(paramiko)
    python3dist(sqlalchemy)
    python3dist(spam)
  stderr_contains: "WARNING: Simplifying 'spam@git+https://github.com/monty/spam.git@master#egg=spam' to 'spam'."
  result: 0

With pyproject.toml, requirements file and without -N option:
  use_build_system: true
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
    lxml: 3.9
    ncclient: 1
    cryptography: 2
    paramiko: 1
    SQLAlchemy: 1.0.90
    argcomplete: 1
    hypothesis: 1
  pyproject.toml: |
    [build-system]
    requires = [
        "foo",
    ]
    build-backend = "foo.build"
  requirements.txt: |
    lxml
    ncclient
    cryptography
    paramiko
    SQLAlchemy
  requirements1.in: |
    argcomplete
    hypothesis
  requirement_files:
    - requirements.txt
    - requirements1.in
  expected: |
    python3dist(lxml)
    python3dist(ncclient)
    python3dist(cryptography)
    python3dist(paramiko)
    python3dist(sqlalchemy)
    python3dist(argcomplete)
    python3dist(hypothesis)
    python3dist(foo)
  result: 0

Value error if -N and -r arguments are present:
  installed:
    # empty
  include_runtime: true
  use_build_system: false
  except: ValueError

Value error if -N and -e arguments are present:
  installed:
    # empty
  toxenv:
    - py3
  use_build_system: false
  except: ValueError

Weird and complex requirements file:
  installed:
    setuptools: 50
    wheel: 1
  setup.py: |
    from setuptools import setup
    setup(
        name='test',
        version='0.1',
    )
  requirements.txt: |
    Normal_Req ~= 1.2.0

    good@git+https://github.com/monty/spam.git@master#egg=bad
    git+https://github.com/monty/spam.git@master#egg=ugly

    this-name-is-too-\
    long-for-this-file<\
    =30  # even names and operators can be split

    # this is not a multi-line comment \
    some-dep
    other-dep  # but this *is* a multi-line coment \
    so any garbage can be here
    dep-a # and this comment ends with the blank line below \

    dep-b
    -r requirements2.txt
    ${PACKAGE}${WANTED_VERSION}
  requirements2.txt: |
    dep-from-included-file
  requirement_files:
    - requirements.txt
  environ:
    PACKAGE: package
    WANTED_VERSION: -from-environ >= 1.2.3
  expected: |
    (python3dist(normal-req) >= 1.2 with python3dist(normal-req) < 1.3)
    python3dist(good)
    python3dist(ugly)
    python3dist(this-name-is-too-long-for-this-file) <= 30
    python3dist(some-dep)
    python3dist(other-dep)
    python3dist(dep-a)
    python3dist(dep-b)
    python3dist(dep-from-included-file)
    python3dist(package-from-environ) >= 1.2.3
  stderr_contains:
  - "WARNING: Simplifying 'good@git+https://github.com/monty/spam.git@master#egg=bad' to 'good'."
  # XXX: pyproject_requirements_txt adds a prefix that's not actually in the source;
  # but that's good enough:
  - "WARNING: Simplifying 'ugly@git+https://github.com/monty/spam.git@master#egg=ugly' to 'ugly'."
  result: 0


Pre-releases are accepted:
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
    cffi: 1.15.0rc2
  pyproject.toml: |
    [build-system]
    requires = [
        "setuptools",
        "wheel",
        "cffi",
    ]
    build-backend = "setuptools.build_meta"
  expected: |
    python3dist(setuptools)
    python3dist(wheel)
    python3dist(cffi)
    python3dist(wheel)
  stderr_contains: "Requirement satisfied: cffi"
  result: 0


Stdout from wrapped subprocess does not appear in output:
  installed:
    setuptools: 50
    wheel: 1
  include_runtime: false
  setup.py: |
    import os
    os.system('echo LEAK?')
    from setuptools import setup
    setup(name='test', version='0.1')
  expected: |
    python3dist(setuptools) >= 40.8
    python3dist(wheel)
    python3dist(wheel)
  result: 0

pyproject.toml with runtime dependencies:
  skipif: not SETUPTOOLS_60
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  pyproject.toml: |
    [build-system]
    requires = ["setuptools"]
    build-backend = "setuptools.build_meta"
    [project]
    name = "my_package"
    version = "0.1"
    dependencies = [
        "foo",
        'importlib-metadata; python_version<"3.8"',
    ]
  expected: |
    python3dist(setuptools)
    python3dist(wheel)
    python3dist(foo)
  result: 0

pyproject.toml with runtime dependencies and partially selected extras:
  skipif: not SETUPTOOLS_60
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  extras:
    - tests
  pyproject.toml: |
    [build-system]
    requires = ["setuptools"]
    build-backend = "setuptools.build_meta"
    [project]
    name = "my_package"
    version = "0.1"
    dependencies = [
        "foo",
        'importlib-metadata; python_version<"3.8"',
    ]
    [project.optional-dependencies]
    tests = ["pytest>=5", "pytest-mock"]
    docs = ["sphinx", "python-docs-theme"]
  expected: |
    python3dist(setuptools)
    python3dist(wheel)
    python3dist(foo)
    python3dist(pytest) >= 5
    python3dist(pytest-mock)
  result: 0

Self-referencing extras (sooner):
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  extras:
    - dev  # this is deliberately sooner in the alphabet than the referenced ones
  pyproject.toml: |
    [build-system]
    requires = ["setuptools"]
    build-backend = "setuptools.build_meta"
  setup.cfg: |
    [metadata]
    name = my_package
    version = 0.1
    [options]
    install_requires =
        foo
        importlib-metadata; python_version<"3.8"
    [options.extras_require]
    tests = pytest>=5; pytest-mock
    docs = sphinx; python-docs-theme
    dev = my_package[docs,tests]
  expected: |
    python3dist(setuptools)
    python3dist(wheel)
    python3dist(foo)
    python3dist(sphinx)
    python3dist(python-docs-theme)
    python3dist(pytest) >= 5
    python3dist(pytest-mock)
  result: 0

Self-referencing extras (later):
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  extras:
    - xdev  # this is deliberately later in the alphabet than the referenced ones
  pyproject.toml: |
    [build-system]
    requires = ["setuptools"]
    build-backend = "setuptools.build_meta"
  setup.cfg: |
    [metadata]
    name = my_package
    version = 0.1
    [options]
    install_requires =
        foo
        importlib-metadata; python_version<"3.8"
    [options.extras_require]
    tests = pytest>=5; pytest-mock
    docs = sphinx; python-docs-theme
    xdev = my_package[docs,tests]
  expected: |
    python3dist(setuptools)
    python3dist(wheel)
    python3dist(foo)
    python3dist(sphinx)
    python3dist(python-docs-theme)
    python3dist(pytest) >= 5
    python3dist(pytest-mock)
  result: 0

Self-referencing extras (maze):
  installed:
    setuptools: 50
    wheel: 1
    toml: 1
  extras:
    - start
  pyproject.toml: |
    [build-system]
    requires = ["setuptools"]
    build-backend = "setuptools.build_meta"
  setup.cfg: |
    [metadata]
    name = my_package
    version = 0.1
    [options.extras_require]
    start = my_package[left,right]; startdep
    left = my_package[right,forward]; leftdep
    right = my_package[left,forward]; rightdep
    forward = my_package[backward]; forwarddep
    backward = my_package[left,right]; backwarddep
    never = my_package[forward]; neverdep
  expected: |
    python3dist(setuptools)
    python3dist(wheel)
    python3dist(backwarddep)
    python3dist(forwarddep)
    python3dist(leftdep)
    python3dist(rightdep)
    python3dist(startdep)
  result: 0