Introduce Config.invocation_params (#5564)

Introduce Config.invocation_params

Author: nicoddemus

changelog/5564.feature.rst

@@ -0,0 +1 @@
+New ``Config.invocation_args`` attribute containing the unchanged arguments passed to ``pytest.main()``.

src/_pytest/config/__init__.py

@@ -8,7 +8,9 @@
 import types
 import warnings
 from functools import lru_cache
+from pathlib import Path
 
+import attr
 import py
 from packaging.version import Version
 from pluggy import HookimplMarker
@@ -148,10 +150,15 @@ def directory_arg(path, optname):
 builtin_plugins.add("pytester")
 
 
-def get_config(args=None):
+def get_config(args=None, plugins=None):
     # subsequent calls to main will create a fresh instance
     pluginmanager = PytestPluginManager()
-    config = Config(pluginmanager)
+    config = Config(
+        pluginmanager,
+        invocation_params=Config.InvocationParams(
+            args=args, plugins=plugins, dir=Path().resolve()
+        ),
+    )
 
     if args is not None:
         # Handle any "-p no:plugin" args.
@@ -184,7 +191,7 @@ def _prepareconfig(args=None, plugins=None):
         msg = "`args` parameter expected to be a list or tuple of strings, got: {!r} (type: {})"
         raise TypeError(msg.format(args, type(args)))
 
-    config = get_config(args)
+    config = get_config(args, plugins)
     pluginmanager = config.pluginmanager
     try:
         if plugins:
@@ -613,20 +620,57 @@ def _iter_rewritable_modules(package_files):
 
 
 class Config:
-    """ access to configuration values, pluginmanager and plugin hooks.  """
+    """
+    Access to configuration values, pluginmanager and plugin hooks.
 
-    def __init__(self, pluginmanager):
-        #: access to command line option as attributes.
-        #: (deprecated), use :py:func:`getoption() <_pytest.config.Config.getoption>` instead
-        self.option = argparse.Namespace()
+    :ivar PytestPluginManager pluginmanager: the plugin manager handles plugin registration and hook invocation.
+
+    :ivar argparse.Namespace option: access to command line option as attributes.
+
+    :ivar InvocationParams invocation_params:
+
+        Object containing the parameters regarding the ``pytest.main``
+        invocation.
+
+        Contains the followinig read-only attributes:
+
+        * ``args``: list of command-line arguments as passed to ``pytest.main()``.
+        * ``plugins``: list of extra plugins, might be None
+        * ``dir``: directory where ``pytest.main()`` was invoked from.
+    """
+
+    @attr.s(frozen=True)
+    class InvocationParams:
+        """Holds parameters passed during ``pytest.main()``
+
+        .. note::
+
+            Currently the environment variable PYTEST_ADDOPTS is also handled by
+            pytest implicitly, not being part of the invocation.
+
+            Plugins accessing ``InvocationParams`` must be aware of that.
+        """
+
+        args = attr.ib()
+        plugins = attr.ib()
+        dir = attr.ib()
+
+    def __init__(self, pluginmanager, *, invocation_params=None):
         from .argparsing import Parser, FILE_OR_DIR
 
+        if invocation_params is None:
+            invocation_params = self.InvocationParams(
+                args=(), plugins=None, dir=Path().resolve()
+            )
+
+        self.option = argparse.Namespace()
+        self.invocation_params = invocation_params
+
         _a = FILE_OR_DIR
         self._parser = Parser(
             usage="%(prog)s [options] [{}] [{}] [...]".format(_a, _a),
             processopt=self._processopt,
         )
-        #: a pluginmanager instance
         self.pluginmanager = pluginmanager
         self.trace = self.pluginmanager.trace.root.get("config")
         self.hook = self.pluginmanager.hook
@@ -636,9 +680,13 @@ def __init__(self, pluginmanager):
         self._cleanup = []
         self.pluginmanager.register(self, "pytestconfig")
         self._configured = False
-        self.invocation_dir = py.path.local()
         self.hook.pytest_addoption.call_historic(kwargs=dict(parser=self._parser))
 
+    @property
+    def invocation_dir(self):
+        """Backward compatibility"""
+        return py.path.local(str(self.invocation_params.dir))
+
     def add_cleanup(self, func):
         """ Add a function to be called when the config object gets out of
         use (usually coninciding with pytest_unconfigure)."""

testing/test_config.py

@@ -1,6 +1,7 @@
 import os
 import sys
 import textwrap
+from pathlib import Path
 
 import _pytest._code
 import pytest
@@ -1199,6 +1200,29 @@ def test_config_does_not_load_blocked_plugin_from_args(testdir):
     assert result.ret == ExitCode.USAGE_ERROR
 
 
+def test_invocation_args(testdir):
+    """Ensure that Config.invocation_* arguments are correctly defined"""
+
+    class DummyPlugin:
+        pass
+
+    p = testdir.makepyfile("def test(): pass")
+    plugin = DummyPlugin()
+    rec = testdir.inline_run(p, "-v", plugins=[plugin])
+    calls = rec.getcalls("pytest_runtest_protocol")
+    assert len(calls) == 1
+    call = calls[0]
+    config = call.item.config
+
+    assert config.invocation_params.args == [p, "-v"]
+    assert config.invocation_params.dir == Path(str(testdir.tmpdir))
+
+    plugins = config.invocation_params.plugins
+    assert len(plugins) == 2
+    assert plugins[0] is plugin
+    assert type(plugins[1]).__name__ == "Collect"  # installed by testdir.inline_run()
+
+
 @pytest.mark.parametrize(
     "plugin",
     [