config: typing for create_terminal_writer, re-export TerminalWriter

This also imports `TerminalWriter` explicitly via `_pytest._io`,
allowing for easier extending / replacing it.

src/_pytest/_code/code.py

@@ -29,6 +29,7 @@ import pluggy
 import py
 
 import _pytest
+from _pytest._io import TerminalWriter
 from _pytest._io.saferepr import safeformat
 from _pytest._io.saferepr import saferepr
 from _pytest.compat import overload
@@ -915,14 +916,14 @@ class TerminalRepr:
         # FYI this is called from pytest-xdist's serialization of exception
         # information.
         io = StringIO()
-        tw = py.io.TerminalWriter(file=io)
+        tw = TerminalWriter(file=io)
         self.toterminal(tw)
         return io.getvalue().strip()
 
     def __repr__(self) -> str:
         return "<{} instance at {:0x}>".format(self.__class__, id(self))
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         raise NotImplementedError()
 
 
@@ -933,7 +934,7 @@ class ExceptionRepr(TerminalRepr):
     def addsection(self, name: str, content: str, sep: str = "-") -> None:
         self.sections.append((name, content, sep))
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         for name, content, sep in self.sections:
             tw.sep(sep, name)
             tw.line(content)
@@ -953,7 +954,7 @@ class ExceptionChainRepr(ExceptionRepr):
         self.reprtraceback = chain[-1][0]
         self.reprcrash = chain[-1][1]
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         for element in self.chain:
             element[0].toterminal(tw)
             if element[2] is not None:
@@ -970,7 +971,7 @@ class ReprExceptionInfo(ExceptionRepr):
         self.reprtraceback = reprtraceback
         self.reprcrash = reprcrash
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         self.reprtraceback.toterminal(tw)
         super().toterminal(tw)
 
@@ -988,7 +989,7 @@ class ReprTraceback(TerminalRepr):
         self.extraline = extraline
         self.style = style
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         # the entries might have different styles
         for i, entry in enumerate(self.reprentries):
             if entry.style == "long":
@@ -1020,7 +1021,7 @@ class ReprEntryNative(TerminalRepr):
     def __init__(self, tblines: Sequence[str]) -> None:
         self.lines = tblines
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         tw.write("".join(self.lines))
 
 
@@ -1039,7 +1040,7 @@ class ReprEntry(TerminalRepr):
         self.reprfileloc = filelocrepr
         self.style = style
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         if self.style == "short":
             assert self.reprfileloc is not None
             self.reprfileloc.toterminal(tw)
@@ -1072,7 +1073,7 @@ class ReprFileLocation(TerminalRepr):
         self.lineno = lineno
         self.message = message
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         # filename and lineno output for each entry,
         # using an output format that most editors understand
         msg = self.message
@@ -1087,7 +1088,7 @@ class ReprLocals(TerminalRepr):
     def __init__(self, lines: Sequence[str]) -> None:
         self.lines = lines
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         for line in self.lines:
             tw.line(line)
 
@@ -1096,7 +1097,7 @@ class ReprFuncArgs(TerminalRepr):
     def __init__(self, args: Sequence[Tuple[str, object]]) -> None:
         self.args = args
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         if self.args:
             linesofar = ""
             for name, value in self.args:

src/_pytest/_io/__init__.py

@@ -0,0 +1,3 @@
+# Reexport TerminalWriter from here instead of py, to make it easier to
+# extend or swap our own implementation in the future.
+from py.io import TerminalWriter as TerminalWriter  # noqa: F401

src/_pytest/cacheprovider.py

@@ -17,6 +17,7 @@ from .pathlib import Path
 from .pathlib import resolve_from_str
 from .pathlib import rm_rf
 from _pytest import nodes
+from _pytest._io import TerminalWriter
 from _pytest.config import Config
 from _pytest.main import Session
 
@@ -418,7 +419,7 @@ def pytest_report_header(config):
 def cacheshow(config, session):
     from pprint import pformat
 
-    tw = py.io.TerminalWriter()
+    tw = TerminalWriter()
     tw.line("cachedir: " + str(config.cache._cachedir))
     if not config.cache._cachedir.is_dir():
         tw.line("cache is empty")

src/_pytest/config/__init__.py

@@ -36,6 +36,7 @@ from .findpaths import determine_setup
 from .findpaths import exists
 from _pytest._code import ExceptionInfo
 from _pytest._code import filter_traceback
+from _pytest._io import TerminalWriter
 from _pytest.compat import importlib_metadata
 from _pytest.compat import TYPE_CHECKING
 from _pytest.outcomes import fail
@@ -73,7 +74,7 @@ def main(args=None, plugins=None) -> "Union[int, _pytest.main.ExitCode]":
             config = _prepareconfig(args, plugins)
         except ConftestImportFailure as e:
             exc_info = ExceptionInfo(e.excinfo)
-            tw = py.io.TerminalWriter(sys.stderr)
+            tw = TerminalWriter(sys.stderr)
             tw.line(
                 "ImportError while loading conftest '{e.path}'.".format(e=e), red=True
             )
@@ -99,7 +100,7 @@ def main(args=None, plugins=None) -> "Union[int, _pytest.main.ExitCode]":
             finally:
                 config._ensure_unconfigure()
     except UsageError as e:
-        tw = py.io.TerminalWriter(sys.stderr)
+        tw = TerminalWriter(sys.stderr)
         for msg in e.args:
             tw.line("ERROR: {}\n".format(msg), red=True)
         return ExitCode.USAGE_ERROR
@@ -1175,12 +1176,12 @@ def setns(obj, dic):
             setattr(pytest, name, value)
 
 
-def create_terminal_writer(config, *args, **kwargs):
+def create_terminal_writer(config: Config, *args, **kwargs) -> TerminalWriter:
     """Create a TerminalWriter instance configured according to the options
     in the config object. Every code which requires a TerminalWriter object
     and has access to a config object should use this function.
     """
-    tw = py.io.TerminalWriter(*args, **kwargs)
+    tw = TerminalWriter(*args, **kwargs)
     if config.option.color == "yes":
         tw.hasmarkup = True
     if config.option.color == "no":

src/_pytest/doctest.py

@@ -13,13 +13,14 @@ from typing import Sequence
 from typing import Tuple
 from typing import Union
 
-import py
+import py.path
 
 import pytest
 from _pytest import outcomes
 from _pytest._code.code import ExceptionInfo
 from _pytest._code.code import ReprFileLocation
 from _pytest._code.code import TerminalRepr
+from _pytest._io import TerminalWriter
 from _pytest.compat import safe_getattr
 from _pytest.compat import TYPE_CHECKING
 from _pytest.fixtures import FixtureRequest
@@ -139,7 +140,7 @@ class ReprFailDoctest(TerminalRepr):
     ):
         self.reprlocation_lines = reprlocation_lines
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         for reprlocation, lines in self.reprlocation_lines:
             for line in lines:
                 tw.line(line)

src/_pytest/fixtures.py

@@ -16,6 +16,7 @@ import py
 import _pytest
 from _pytest._code.code import FormattedExcinfo
 from _pytest._code.code import TerminalRepr
+from _pytest._io import TerminalWriter
 from _pytest.compat import _format_args
 from _pytest.compat import _PytestWrapper
 from _pytest.compat import get_real_func
@@ -754,7 +755,7 @@ class FixtureLookupErrorRepr(TerminalRepr):
         self.firstlineno = firstlineno
         self.argname = argname
 
-    def toterminal(self, tw: py.io.TerminalWriter) -> None:
+    def toterminal(self, tw: TerminalWriter) -> None:
         # tw.line("FixtureLookupError: %s" %(self.argname), red=True)
         for tbline in self.tblines:
             tw.line(tbline.rstrip())

src/_pytest/reports.py

@@ -18,6 +18,7 @@ from _pytest._code.code import ReprFuncArgs
 from _pytest._code.code import ReprLocals
 from _pytest._code.code import ReprTraceback
 from _pytest._code.code import TerminalRepr
+from _pytest._io import TerminalWriter
 from _pytest.compat import TYPE_CHECKING
 from _pytest.nodes import Node
 from _pytest.outcomes import skip
@@ -80,7 +81,7 @@ class BaseReport:
 
         .. versionadded:: 3.0
         """
-        tw = py.io.TerminalWriter(stringio=True)
+        tw = TerminalWriter(stringio=True)
         tw.hasmarkup = False
         self.toterminal(tw)
         exc = tw.stringio.getvalue()