terminalwriter: add type annotations

src/_pytest/_io/terminalwriter.py

@@ -4,7 +4,9 @@ import shutil
 import sys
 import unicodedata
 from functools import lru_cache
+from typing import Optional
 from typing import Sequence
+from typing import TextIO
 
 
 # This code was initially copied from py 1.8.1, file _io/terminalwriter.py.
@@ -26,12 +28,12 @@ def char_width(c: str) -> int:
     return 2 if unicodedata.east_asian_width(c) in ("F", "W") else 1
 
 
-def get_line_width(text):
+def get_line_width(text: str) -> int:
     text = unicodedata.normalize("NFC", text)
     return sum(char_width(c) for c in text)
 
 
-def should_do_markup(file):
+def should_do_markup(file: TextIO) -> bool:
     if os.environ.get("PY_COLORS") == "1":
         return True
     if os.environ.get("PY_COLORS") == "0":
@@ -68,7 +70,7 @@ class TerminalWriter:
         invert=7,
     )
 
-    def __init__(self, file=None):
+    def __init__(self, file: Optional[TextIO] = None) -> None:
         if file is None:
             file = sys.stdout
         if hasattr(file, "isatty") and file.isatty() and sys.platform == "win32":
@@ -78,38 +80,33 @@ class TerminalWriter:
                 pass
             else:
                 file = colorama.AnsiToWin32(file).stream
+                assert file is not None
         self._file = file
         self.hasmarkup = should_do_markup(file)
         self._chars_on_current_line = 0
         self._width_of_current_line = 0
 
     @property
-    def fullwidth(self):
+    def fullwidth(self) -> int:
         if hasattr(self, "_terminal_width"):
             return self._terminal_width
         return get_terminal_width()
 
     @fullwidth.setter
-    def fullwidth(self, value):
+    def fullwidth(self, value: int) -> None:
         self._terminal_width = value
 
     @property
-    def chars_on_current_line(self):
-        """Return the number of characters written so far in the current line.
-
-        :rtype: int
-        """
+    def chars_on_current_line(self) -> int:
+        """Return the number of characters written so far in the current line."""
         return self._chars_on_current_line
 
     @property
-    def width_of_current_line(self):
-        """Return an estimate of the width so far in the current line.
-
-        :rtype: int
-        """
+    def width_of_current_line(self) -> int:
+        """Return an estimate of the width so far in the current line."""
         return self._width_of_current_line
 
-    def markup(self, text, **kw):
+    def markup(self, text: str, **kw: bool) -> str:
         esc = []
         for name in kw:
             if name not in self._esctable:
@@ -120,7 +117,13 @@ class TerminalWriter:
             text = "".join("\x1b[%sm" % cod for cod in esc) + text + "\x1b[0m"
         return text
 
-    def sep(self, sepchar, title=None, fullwidth=None, **kw):
+    def sep(
+        self,
+        sepchar: str,
+        title: Optional[str] = None,
+        fullwidth: Optional[int] = None,
+        **kw: bool
+    ) -> None:
         if fullwidth is None:
             fullwidth = self.fullwidth
         # the goal is to have the line be as long as possible
@@ -151,7 +154,7 @@ class TerminalWriter:
 
         self.line(line, **kw)
 
-    def write(self, msg: str, **kw) -> None:
+    def write(self, msg: str, **kw: bool) -> None:
         if msg:
             self._update_chars_on_current_line(msg)
 
@@ -171,7 +174,7 @@ class TerminalWriter:
             self._chars_on_current_line += len(current_line)
             self._width_of_current_line += get_line_width(current_line)
 
-    def line(self, s: str = "", **kw):
+    def line(self, s: str = "", **kw: bool) -> None:
         self.write(s, **kw)
         self.write("\n")
 
@@ -195,8 +198,8 @@ class TerminalWriter:
         for indent, new_line in zip(indents, new_lines):
             self.line(indent + new_line)
 
-    def _highlight(self, source):
-        """Highlight the given source code if we have markup support"""
+    def _highlight(self, source: str) -> str:
+        """Highlight the given source code if we have markup support."""
         if not self.hasmarkup:
             return source
         try:
@@ -206,4 +209,7 @@ class TerminalWriter:
         except ImportError:
             return source
         else:
-            return highlight(source, PythonLexer(), TerminalFormatter(bg="dark"))
+            highlighted = highlight(
+                source, PythonLexer(), TerminalFormatter(bg="dark")
+            )  # type: str
+            return highlighted