Drop attrs dependency, use dataclasses instead

Since pytest now requires Python>=3.7, we can use the stdlib attrs
clone, dataclasses, instead of the OG package.

attrs is still somewhat nicer than dataclasses and has some extra
functionality, but for pytest usage there's not really a justification
IMO to impose the extra dependency on users when a standard alternative
exists.

Author: bluetech

changelog/TBD.trivial.rst

@@ -0,0 +1 @@
+pytest no longer depends on the `attrs` package (don't worry, nice diffs for attrs classes are still supported).

setup.cfg

@@ -44,7 +44,6 @@ packages =
     pytest
 py_modules = py
 install_requires =
-    attrs>=19.2.0
     iniconfig
     packaging
     pluggy>=0.12,<2.0
@@ -68,6 +67,7 @@ console_scripts =
 [options.extras_require]
 testing =
     argcomplete
+    attrs>=19.2.0
     hypothesis>=3.56
     mock
     nose

src/_pytest/_code/code.py

@@ -1,4 +1,5 @@
 import ast
+import dataclasses
 import inspect
 import os
 import re
@@ -32,7 +33,6 @@
 from typing import Union
 from weakref import ref
 
-import attr
 import pluggy
 
 import _pytest
@@ -445,7 +445,7 @@ def recursionindex(self) -> Optional[int]:
 
 
 @final
-@attr.s(repr=False, init=False, auto_attribs=True)
+@dataclasses.dataclass
 class ExceptionInfo(Generic[E]):
     """Wraps sys.exc_info() objects and offers help for navigating the traceback."""
 
@@ -649,12 +649,12 @@ def getrepr(
         """
         if style == "native":
             return ReprExceptionInfo(
-                ReprTracebackNative(
+                reprtraceback=ReprTracebackNative(
                     traceback.format_exception(
                         self.type, self.value, self.traceback[0]._rawentry
                     )
                 ),
-                self._getreprcrash(),
+                reprcrash=self._getreprcrash(),
             )
 
         fmt = FormattedExcinfo(
@@ -684,7 +684,7 @@ def match(self, regexp: Union[str, Pattern[str]]) -> "Literal[True]":
         return True
 
 
-@attr.s(auto_attribs=True)
+@dataclasses.dataclass
 class FormattedExcinfo:
     """Presenting information about failing Functions and Generators."""
 
@@ -699,8 +699,8 @@ class FormattedExcinfo:
     funcargs: bool = False
     truncate_locals: bool = True
     chain: bool = True
-    astcache: Dict[Union[str, Path], ast.AST] = attr.ib(
-        factory=dict, init=False, repr=False
+    astcache: Dict[Union[str, Path], ast.AST] = dataclasses.field(
+        default_factory=dict, init=False, repr=False
     )
 
     def _getindent(self, source: "Source") -> int:
@@ -978,7 +978,7 @@ def repr_excinfo(
         return ExceptionChainRepr(repr_chain)
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class TerminalRepr:
     def __str__(self) -> str:
         # FYI this is called from pytest-xdist's serialization of exception
@@ -996,14 +996,14 @@ def toterminal(self, tw: TerminalWriter) -> None:
 
 
 # This class is abstract -- only subclasses are instantiated.
-@attr.s(eq=False)
+@dataclasses.dataclass(eq=False)
 class ExceptionRepr(TerminalRepr):
     # Provided by subclasses.
-    reprcrash: Optional["ReprFileLocation"]
     reprtraceback: "ReprTraceback"
-
-    def __attrs_post_init__(self) -> None:
-        self.sections: List[Tuple[str, str, str]] = []
+    reprcrash: Optional["ReprFileLocation"]
+    sections: List[Tuple[str, str, str]] = dataclasses.field(
+        init=False, default_factory=list
+    )
 
     def addsection(self, name: str, content: str, sep: str = "-") -> None:
         self.sections.append((name, content, sep))
@@ -1014,16 +1014,23 @@ def toterminal(self, tw: TerminalWriter) -> None:
             tw.line(content)
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ExceptionChainRepr(ExceptionRepr):
     chain: Sequence[Tuple["ReprTraceback", Optional["ReprFileLocation"], Optional[str]]]
 
-    def __attrs_post_init__(self) -> None:
-        super().__attrs_post_init__()
+    def __init__(
+        self,
+        chain: Sequence[
+            Tuple["ReprTraceback", Optional["ReprFileLocation"], Optional[str]]
+        ],
+    ) -> None:
         # reprcrash and reprtraceback of the outermost (the newest) exception
         # in the chain.
-        self.reprtraceback = self.chain[-1][0]
-        self.reprcrash = self.chain[-1][1]
+        super().__init__(
+            reprtraceback=chain[-1][0],
+            reprcrash=chain[-1][1],
+        )
+        self.chain = chain
 
     def toterminal(self, tw: TerminalWriter) -> None:
         for element in self.chain:
@@ -1034,7 +1041,7 @@ def toterminal(self, tw: TerminalWriter) -> None:
         super().toterminal(tw)
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprExceptionInfo(ExceptionRepr):
     reprtraceback: "ReprTraceback"
     reprcrash: "ReprFileLocation"
@@ -1044,7 +1051,7 @@ def toterminal(self, tw: TerminalWriter) -> None:
         super().toterminal(tw)
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprTraceback(TerminalRepr):
     reprentries: Sequence[Union["ReprEntry", "ReprEntryNative"]]
     extraline: Optional[str]
@@ -1073,12 +1080,12 @@ def toterminal(self, tw: TerminalWriter) -> None:
 
 class ReprTracebackNative(ReprTraceback):
     def __init__(self, tblines: Sequence[str]) -> None:
-        self.style = "native"
         self.reprentries = [ReprEntryNative(tblines)]
         self.extraline = None
+        self.style = "native"
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprEntryNative(TerminalRepr):
     lines: Sequence[str]
 
@@ -1088,7 +1095,7 @@ def toterminal(self, tw: TerminalWriter) -> None:
         tw.write("".join(self.lines))
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprEntry(TerminalRepr):
     lines: Sequence[str]
     reprfuncargs: Optional["ReprFuncArgs"]
@@ -1168,12 +1175,15 @@ def __str__(self) -> str:
         )
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprFileLocation(TerminalRepr):
-    path: str = attr.ib(converter=str)
+    path: str
     lineno: int
     message: str
 
+    def __post_init__(self) -> None:
+        self.path = str(self.path)
+
     def toterminal(self, tw: TerminalWriter) -> None:
         # Filename and lineno output for each entry, using an output format
         # that most editors understand.
@@ -1185,7 +1195,7 @@ def toterminal(self, tw: TerminalWriter) -> None:
         tw.line(f":{self.lineno}: {msg}")
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprLocals(TerminalRepr):
     lines: Sequence[str]
 
@@ -1194,7 +1204,7 @@ def toterminal(self, tw: TerminalWriter, indent="") -> None:
             tw.line(indent + line)
 
 
-@attr.s(eq=False, auto_attribs=True)
+@dataclasses.dataclass(eq=False)
 class ReprFuncArgs(TerminalRepr):
     args: Sequence[Tuple[str, object]]
 

src/_pytest/cacheprovider.py

@@ -1,6 +1,7 @@
 """Implementation of the cache provider."""
 # This plugin was not named "cache" to avoid conflicts with the external
 # pytest-cache version.
+import dataclasses
 import json
 import os
 from pathlib import Path
@@ -12,8 +13,6 @@
 from typing import Set
 from typing import Union
 
-import attr
-
 from .pathlib import resolve_from_str
 from .pathlib import rm_rf
 from .reports import CollectReport
@@ -53,10 +52,10 @@
 
 
 @final
-@attr.s(init=False, auto_attribs=True)
+@dataclasses.dataclass
 class Cache:
-    _cachedir: Path = attr.ib(repr=False)
-    _config: Config = attr.ib(repr=False)
+    _cachedir: Path = dataclasses.field(repr=False)
+    _config: Config = dataclasses.field(repr=False)
 
     # Sub-directory under cache-dir for directories created by `mkdir()`.
     _CACHE_PREFIX_DIRS = "d"

src/_pytest/compat.py

@@ -1,4 +1,5 @@
 """Python version compatibility code."""
+import dataclasses
 import enum
 import functools
 import inspect
@@ -17,8 +18,6 @@
 from typing import TypeVar
 from typing import Union
 
-import attr
-
 import py
 
 # fmt: off
@@ -253,7 +252,7 @@ def ascii_escaped(val: Union[bytes, str]) -> str:
     return _translate_non_printable(ret)
 
 
-@attr.s
+@dataclasses.dataclass
 class _PytestWrapper:
     """Dummy wrapper around a function object for internal use only.
 
@@ -262,7 +261,7 @@ class _PytestWrapper:
     decorator to issue warnings when the fixture function is called directly.
     """
 
-    obj = attr.ib()
+    obj: Any
 
 
 def get_real_func(obj):

src/_pytest/config/__init__.py

@@ -2,6 +2,7 @@
 import argparse
 import collections.abc
 import copy
+import dataclasses
 import enum
 import glob
 import inspect
@@ -34,7 +35,6 @@
 from typing import TYPE_CHECKING
 from typing import Union
 
-import attr
 from pluggy import HookimplMarker
 from pluggy import HookspecMarker
 from pluggy import PluginManager
@@ -886,10 +886,6 @@ def _iter_rewritable_modules(package_files: Iterable[str]) -> Iterator[str]:
             yield from _iter_rewritable_modules(new_package_files)
 
 
-def _args_converter(args: Iterable[str]) -> Tuple[str, ...]:
-    return tuple(args)
-
-
 @final
 class Config:
     """Access to configuration values, pluginmanager and plugin hooks.
@@ -903,7 +899,7 @@ class Config:
     """
 
     @final
-    @attr.s(frozen=True, auto_attribs=True)
+    @dataclasses.dataclass(frozen=True)
     class InvocationParams:
         """Holds parameters passed during :func:`pytest.main`.
 
@@ -919,13 +915,24 @@ class InvocationParams:
             Plugins accessing ``InvocationParams`` must be aware of that.
         """
 
-        args: Tuple[str, ...] = attr.ib(converter=_args_converter)
+        args: Tuple[str, ...]
         """The command-line arguments as passed to :func:`pytest.main`."""
         plugins: Optional[Sequence[Union[str, _PluggyPlugin]]]
         """Extra plugins, might be `None`."""
         dir: Path
         """The directory from which :func:`pytest.main` was invoked."""
 
+        def __init__(
+            self,
+            *,
+            args: Iterable[str],
+            plugins: Optional[Sequence[Union[str, _PluggyPlugin]]],
+            dir: Path,
+        ) -> None:
+            object.__setattr__(self, "args", tuple(args))
+            object.__setattr__(self, "plugins", plugins)
+            object.__setattr__(self, "dir", dir)
+
     class ArgsSource(enum.Enum):
         """Indicates the source of the test arguments.