improve line width estimate

changelog/3911.bugfix.rst

@@ -0,0 +1 @@
+Terminal writer now takes into account unicode character width when writing out progress.

setup.py

@@ -59,7 +59,7 @@ def get_environment_marker_support_level():
 def main():
     extras_require = {}
     install_requires = [
-        "py>=1.5.0",
+        "py>=1.5.0",  # if py gets upgrade to >=1.6, remove _width_of_current_line in terminal.py
         "six>=1.10.0",
         "setuptools",
         "attrs>=17.4.0",

src/_pytest/terminal.py

@@ -412,10 +412,8 @@ def pytest_runtest_logfinish(self, nodeid):
             if last_item:
                 self._write_progress_information_filling_space()
             else:
-                past_edge = (
-                    self._tw.chars_on_current_line + self._PROGRESS_LENGTH + 1
-                    >= self._screen_width
-                )
+                w = self._width_of_current_line
+                past_edge = w + self._PROGRESS_LENGTH + 1 >= self._screen_width
                 if past_edge:
                     msg = self._get_progress_information_message()
                     self._tw.write(msg + "\n", cyan=True)
@@ -433,10 +431,18 @@ def _get_progress_information_message(self):
 
     def _write_progress_information_filling_space(self):
         msg = self._get_progress_information_message()
-        fill = " " * (
-            self._tw.fullwidth - self._tw.chars_on_current_line - len(msg) - 1
-        )
-        self.write(fill + msg, cyan=True)
+        w = self._width_of_current_line
+        fill = self._tw.fullwidth - w - 1
+        self.write(msg.rjust(fill), cyan=True)
+
+    @property
+    def _width_of_current_line(self):
+        """Return the width of current line, using the superior implementation of py-1.6 when available"""
+        try:
+            return self._tw.width_of_current_line
+        except AttributeError:
+            # py < 1.6.0
+            return self._tw.chars_on_current_line
 
     def pytest_collection(self):
         if not self.isatty and self.config.option.verbose >= 1: