Add the --print-extras-to(-file) option

README.rst

@@ -5,7 +5,7 @@ tox-current-env
 `tox <https://tox.readthedocs.io/>`_  plugin to run tests in current Python environment
 ---------------------------------------------------------------------------------------
 
-The ``tox-current-env`` plugin adds two options:
+The ``tox-current-env`` plugin adds these options:
 
 ``tox --current-env``
    Runs the tox testenv's ``commands`` in the current Python environment
@@ -15,11 +15,21 @@ The ``tox-current-env`` plugin adds two options:
    (if ``tox`` is invoked from an Python 3.7 environment, any non 3.7 testenv will fail).
 
 ``tox --print-deps-to=FILE``
-    Instead of running any ``commands``,
-    simply prints the declared dependencies in ``deps`` to the specified ``FILE``.
-    This is useful for preparing the current environment for the above.
+    Instead of running any ``commands``, simply prints the
+    `declared dependencies <https://tox.readthedocs.io/en/latest/config.html#conf-deps>`_
+    in ``deps`` to the specified ``FILE``.
+    This is useful for preparing the current environment for ``tox --current-env``.
     Use ``-`` for ``FILE`` to print to standard output.
 
+``tox --print-extras-to=FILE``
+    Instead of running any ``commands``, simply prints the names of the
+    `declared extras <https://tox.readthedocs.io/en/latest/config.html#conf-extras>`_
+    in ``extras`` to the specified ``FILE``.
+    This is useful for preparing the current environment for ``tox --current-env``.
+    Use ``-`` for ``FILE`` to print to standard output.
+
+It is possible to use the two printing options together, as long as the ``FILE`` is different.
+
 Invoking ``tox`` without any of the above options should behave as regular ``tox`` invocation without this plugin.
 Any deviation from this behavior is considered a bug.
 
@@ -82,7 +92,10 @@ and ``pip``-installing locally:
 Usage
 -----
 
-When the plugin is installed, use ``tox`` with ``--current-env`` or ``--print-deps-to`` and all the other options as usual. Assuming your ``tox`` is installed on Python 3.7:
+When the plugin is installed,
+use ``tox`` with ``--current-env``, ``--print-deps-to`` or ``--print-extras-to``
+and all the other options as usual.
+Assuming your ``tox`` is installed on Python 3.7:
 
 .. code-block:: console
 
@@ -125,6 +138,21 @@ To get list of test dependencies, run:
      py37: commands succeeded
      congratulations :)
 
+To get a list of names of extras, run:
+
+.. code-block:: console
+
+   $ tox -e py37 --print-extras-to -
+   py37 create: /home/pythonista/projects/holy-grail/tests/.tox/py37
+   py37 installed: ...you can see almost anything here...
+   py37 run-test-pre: PYTHONHASHSEED='3333333333'
+   extra1
+   extra2
+   ...
+   ___________________________________ summary ____________________________________
+     py37: commands succeeded
+     congratulations :)
+
 
 Caveats, warnings and limitations
 ---------------------------------
@@ -159,8 +187,8 @@ Don't mix current-env and regular tox runs
 
 Tox caches the virtualenvs it creates, and doesn't distinguish between
 regular virtualenvs and ``--current-env``.
-Don't mix ``tox --current-env`` or ``tox --print-deps-to`` runs
-and regular ``tox`` runs (without the flag).
+Don't mix ``tox --current-env``, ``tox --print-deps-to`` or ``tox --print-extras-to``
+runs and regular ``tox`` runs (without the flags provided by this plugin).
 If you ever need to do this, use tox's ``--recreate/-r`` flag to clear the cache.
 
 The plugin should abort with a meaningful error message if this is detected,
@@ -183,7 +211,7 @@ Read `the documentation for passing environment variables to tox
 Other limitations and known bugs
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The ``installed:`` line in the output of ``tox --print-deps-to`` shows irrelevant output
+The ``installed:`` line in the output of ``tox --print-deps-to``/``tox --print-extras-to`` shows irrelevant output
 (based on the content of the real or faked virtual environment).
 
 Regardless of any `Python flags <https://docs.python.org/3/using/cmdline.html>`_ used in the shebang of ``tox``,

src/tox_current_env/hooks.py

@@ -38,6 +38,16 @@ def tox_addoption(parser):
         help="Don't run tests, only print the dependencies to the given file "
             + "(use `-` for stdout)",
     )
+    parser.add_argument(
+        "--print-extras-to",
+        "--print-extras-to-file",
+        action="store",
+        type=argparse.FileType('w'),
+        metavar="FILE",
+        default=None,
+        help="Don't run tests, only print the  names of the required extras to the given file "
+            + "(use `-` for stdout)",
+    )
 
 
 @tox.hookimpl
@@ -55,11 +65,17 @@ def tox_configure(config):
                 "--print-deps-only cannot be used together "
                 + "with --print-deps-to"
             )
-    if config.option.current_env or config.option.print_deps_to:
+    if config.option.current_env or config.option.print_deps_to or config.option.print_extras_to:
         config.skipsdist = True
         for testenv in config.envconfigs:
             config.envconfigs[testenv].whitelist_externals = "*"
 
+    if (getattr(config.option.print_deps_to, "name", object()) ==
+        getattr(config.option.print_extras_to, "name", object())):
+            raise tox.exception.ConfigError(
+                "The paths given to --print-deps-to and --print-extras-to cannot be identical."
+            )
+
     return config
 
 
@@ -97,16 +113,17 @@ def rm_venv(venv):
 def unsupported_raise(config, venv):
     if config.option.recreate:
         return
-    regular = not (config.option.current_env or config.option.print_deps_to)
+    regular = not (config.option.current_env or config.option.print_deps_to or config.option.print_extras_to)
     if regular and is_current_env_link(venv):
         if hasattr(tox.hookspecs, "tox_cleanup"):
             raise tox.exception.ConfigError(
-                "Looks like previous --current-env or --print-deps-to tox run didn't finish the cleanup. "
+                "Looks like previous --current-env, --print-deps-to or --print-extras-to tox run didn't finish the cleanup. "
                 "Run tox run with --recreate (-r) or manually remove the environment in .tox."
             )
         else:
             raise tox.exception.ConfigError(
-                "Regular tox run after --current-env or --print-deps-to tox run is not supported without --recreate (-r)."
+                "Regular tox run after --current-env, --print-deps-to or --print-extras-to tox run "
+                "is not supported without --recreate (-r)."
             )
     elif config.option.current_env and is_proper_venv(venv):
         raise tox.exception.ConfigError(
@@ -119,7 +136,7 @@ def tox_testenv_create(venv, action):
     """We create a fake virtualenv with just the symbolic link"""
     config = venv.envconfig.config
     create_fake_env = check_version = config.option.current_env
-    if config.option.print_deps_to:
+    if config.option.print_deps_to or config.option.print_extras_to:
         if is_any_env(venv):
             # We don't need anything
             return True
@@ -130,7 +147,7 @@ def tox_testenv_create(venv, action):
             # because it's cheaper, faster and won't install stuff
             create_fake_env = True
     if check_version:
-        # With real --current-env, we check this, but not with --print-deps-to only
+        # With real --current-env, we check this, but not with --print-deps/extras-to only
         version_info = venv.envconfig.python_info.version_info
         if version_info is None:
             raise tox.exception.InterpreterNotFound(venv.envconfig.basepython)
@@ -178,16 +195,30 @@ def tox_testenv_install_deps(venv, action):
 
 @tox.hookimpl
 def tox_runtest(venv, redirect):
-    """If --print-deps-to, prints deps instead of running tests"""
+    """If --print-deps-to, prints deps instead of running tests.
+    If --print-extras-to, prints extras instead of running tests.
+    Both options can be used together."""
     config = venv.envconfig.config
     unsupported_raise(config, venv)
+    ret = None
+
     if config.option.print_deps_to:
         print(
             *venv.get_resolved_dependencies(),
             sep="\n",
             file=config.option.print_deps_to,
         )
-        return True
+        ret = True
+
+    if config.option.print_extras_to:
+        print(
+            *venv.envconfig.extras,
+            sep="\n",
+            file=config.option.print_extras_to,
+        )
+        ret = True
+
+    return ret
 
 
 @tox.hookimpl

tests/fixtures/setup.py

@@ -1,3 +1,9 @@
 from setuptools import setup
 
-setup(name="test")
+setup(
+    name="test",
+    extras_require={
+        "dev":  [],
+        "full": [],
+    }
+)

tests/fixtures/tox.ini

@@ -5,5 +5,8 @@ envlist = py36,py37,py38,py39
 deps =
     six
     py
+extras =
+    dev
+    full
 commands =
     python -c 'import os, sys; print(os.path.realpath(sys.exec_prefix), "is the exec_prefix")'

tests/test_integration.py

@@ -36,6 +36,12 @@ def print_deps_stdout_arg(request):
     return request.param
 
 
+@pytest.fixture(params=('--print-extras-to-file=-', '--print-extras-to=-'))
+def print_extras_stdout_arg(request):
+    """Argument for printing extras to stdout"""
+    return request.param
+
+
 def tox(*args, quiet=True, **kwargs):
     kwargs.setdefault("encoding", "utf-8")
     kwargs.setdefault("stdout", subprocess.PIPE)
@@ -121,6 +127,21 @@ def test_print_deps(toxenv, print_deps_stdout_arg):
     assert result.stdout == expected
 
 
+@pytest.mark.parametrize("toxenv", ["py36", "py37", "py38", "py39"])
+def test_print_extras(toxenv, print_extras_stdout_arg):
+    result = tox("-e", toxenv, print_extras_stdout_arg)
+    expected = textwrap.dedent(
+        f"""
+        dev
+        full
+        ___________________________________ summary ____________________________________
+          {toxenv}: commands succeeded
+          congratulations :)
+        """
+    ).lstrip()
+    assert result.stdout == expected
+
+
 @pytest.mark.parametrize("toxenv", ["py36", "py37", "py38", "py39"])
 def test_print_deps_only_deprecated(toxenv):
     result = tox(
@@ -157,6 +178,29 @@ def test_allenvs_print_deps(print_deps_stdout_arg):
     assert result.stdout == expected
 
 
+def test_allenvs_print_extras(print_extras_stdout_arg):
+    result = tox(print_extras_stdout_arg)
+    expected = textwrap.dedent(
+        """
+        dev
+        full
+        dev
+        full
+        dev
+        full
+        dev
+        full
+        ___________________________________ summary ____________________________________
+          py36: commands succeeded
+          py37: commands succeeded
+          py38: commands succeeded
+          py39: commands succeeded
+          congratulations :)
+        """
+    ).lstrip()
+    assert result.stdout == expected
+
+
 @pytest.mark.parametrize("toxenv", ["py36", "py37", "py38", "py39"])
 def test_print_deps_to_file(toxenv, tmp_path):
     depspath = tmp_path / "deps"
@@ -172,6 +216,21 @@ def test_print_deps_to_file(toxenv, tmp_path):
     assert result.stdout == expected
 
 
+@pytest.mark.parametrize("toxenv", ["py36", "py37", "py38", "py39"])
+def test_print_extras_to_file(toxenv, tmp_path):
+    extraspath = tmp_path / "extras"
+    result = tox("-e", toxenv, "--print-extras-to", str(extraspath))
+    assert extraspath.read_text().splitlines() == ["dev", "full"]
+    expected = textwrap.dedent(
+        f"""
+        ___________________________________ summary ____________________________________
+          {toxenv}: commands succeeded
+          congratulations :)
+        """
+    ).lstrip()
+    assert result.stdout == expected
+
+
 @pytest.mark.parametrize('option', ('--print-deps-to', '--print-deps-to-file'))
 def test_allenvs_print_deps_to_file(tmp_path, option):
     depspath = tmp_path / "deps"
@@ -190,6 +249,24 @@ def test_allenvs_print_deps_to_file(tmp_path, option):
     assert result.stdout == expected
 
 
+@pytest.mark.parametrize('option', ('--print-extras-to', '--print-extras-to-file'))
+def test_allenvs_print_extras_to_file(tmp_path, option):
+    extraspath = tmp_path / "extras"
+    result = tox(option, str(extraspath))
+    assert extraspath.read_text().splitlines() == ["dev", "full"] * 4
+    expected = textwrap.dedent(
+        """
+        ___________________________________ summary ____________________________________
+          py36: commands succeeded
+          py37: commands succeeded
+          py38: commands succeeded
+          py39: commands succeeded
+          congratulations :)
+        """
+    ).lstrip()
+    assert result.stdout == expected
+
+
 def test_allenvs_print_deps_to_existing_file(tmp_path):
     depspath = tmp_path / "deps"
     depspath.write_text("nada")
@@ -200,6 +277,75 @@ def test_allenvs_print_deps_to_existing_file(tmp_path):
     assert "py" in lines
 
 
+def test_allenvs_print_extras_to_existing_file(tmp_path):
+    extraspath = tmp_path / "extras"
+    extraspath.write_text("nada")
+    result = tox("--print-extras-to", str(extraspath))
+    lines = extraspath.read_text().splitlines()
+    assert "nada" not in lines
+    assert "dev" in lines
+    assert "full" in lines
+
+
+@pytest.mark.parametrize("deps_stdout", [True, False])
+@pytest.mark.parametrize("extras_stdout", [True, False])
+def test_allenvs_print_deps_to_file_print_extras_to_other_file(tmp_path, deps_stdout, extras_stdout):
+    if deps_stdout and extras_stdout:
+        pytest.xfail("Unsupported combination of parameters")
+
+    depspath = "-" if deps_stdout else tmp_path / "deps"
+    extraspath = "-" if extras_stdout else tmp_path / "extras"
+    result = tox("--print-deps-to", str(depspath),
+                 "--print-extras-to", str(extraspath))
+    if deps_stdout:
+        depslines = result.stdout.splitlines()
+        extraslines = extraspath.read_text().splitlines()
+    elif extras_stdout:
+        depslines = depspath.read_text().splitlines()
+        extraslines = result.stdout.splitlines()
+    else:
+        extraslines = extraspath.read_text().splitlines()
+        depslines = depspath.read_text().splitlines()
+
+    assert "six" in depslines
+    assert "py" in depslines
+    assert "full" in extraslines
+    assert "dev" in extraslines
+
+    assert "six" not in extraslines
+    assert "py" not in extraslines
+    assert "full" not in depslines
+    assert "dev" not in depslines
+
+
+def test_print_deps_extras_to_same_file_is_not_possible(tmp_path):
+    depsextraspath = tmp_path / "depsextras"
+    result = tox(
+        "-e",
+        NATIVE_TOXENV,
+        "--print-deps-to", str(depsextraspath),
+        "--print-extras-to", str(depsextraspath),
+        check=False,
+    )
+    assert result.returncode > 0
+    assert "cannot be identical" in result.stderr
+
+
+def test_print_deps_extras_to_stdout_is_not_possible(
+        tmp_path,
+        print_deps_stdout_arg,
+        print_extras_stdout_arg,):
+    result = tox(
+        "-e",
+        NATIVE_TOXENV,
+        print_deps_stdout_arg,
+        print_extras_stdout_arg,
+        check=False,
+    )
+    assert result.returncode > 0
+    assert "cannot be identical" in result.stderr
+
+
 def test_print_deps_only_print_deps_to_file_are_mutually_exclusive():
     result = tox(
         "-e",
@@ -319,6 +465,16 @@ def test_current_after_print_deps(print_deps_stdout_arg):
         assert result.stdout.splitlines()[0] == NATIVE_EXEC_PREFIX_MSG
 
 
+def test_current_after_print_extras(print_extras_stdout_arg):
+    # this is quite fast, so we can do it several times
+    for _ in range(3):
+        result = tox("-e", NATIVE_TOXENV, print_extras_stdout_arg)
+        assert "bin/python" not in result.stdout
+        assert "full" in result.stdout
+        result = tox("-re", NATIVE_TOXENV, "--current-env")
+        assert result.stdout.splitlines()[0] == NATIVE_EXEC_PREFIX_MSG
+
+
 def test_regular_recreate_after_print_deps(print_deps_stdout_arg):
     result = tox("-e", NATIVE_TOXENV, print_deps_stdout_arg)
     assert "bin/python" not in result.stdout