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: