Fix small terminal glitch when collecting a single test item

Fix pytest-dev#2579

_pytest/terminal.py

@@ -180,8 +180,22 @@ def write_line(self, line, **markup):
         self._tw.line(line, **markup)
 
     def rewrite(self, line, **markup):
+        """
+        Rewinds the terminal cursor to the beginning and writes the given line.
+
+        :kwarg erase: if True, will also add spaces until the full terminal width to ensure
+            previous lines are properly erased.
+
+        The rest of the keyword arguments are markup instructions.
+        """
+        erase = markup.pop('erase', False)
+        if erase:
+            fill_count = self._tw.fullwidth - len(line)
+            fill = ' ' * fill_count
+        else:
+            fill = ''
         line = str(line)
-        self._tw.write("\r" + line, **markup)
+        self._tw.write("\r" + line + fill, **markup)
 
     def write_sep(self, sep, title=None, **markup):
         self.ensure_newline()
@@ -292,12 +306,9 @@ def report_collect(self, final=False):
         if skipped:
             line += " / %d skipped" % skipped
         if self.isatty:
+            self.rewrite(line, bold=True, erase=True)
             if final:
-                line += " \n"
-                # Rewrite with empty line so we will not see the artifact of
-                # previous write
-                self.rewrite('')
-            self.rewrite(line, bold=True)
+                self.write('\n')
         else:
             self.write_line(line)
 

changelog/2579.bugfix

@@ -0,0 +1 @@
+Fixed small terminal glitch when collecting a single test item.

testing/test_terminal.py

@@ -214,6 +214,16 @@ def test_foobar():
         result = testdir.runpytest()
         result.stdout.fnmatch_lines(['collected 1 item'])
 
+    def test_rewrite(self, testdir, monkeypatch):
+        config = testdir.parseconfig()
+        f = py.io.TextIO()
+        monkeypatch.setattr(f, 'isatty', lambda *args: True)
+        tr = TerminalReporter(config, f)
+        tr.writer.fullwidth = 10
+        tr.write('hello')
+        tr.rewrite('hey', erase=True)
+        assert f.getvalue() == 'hello' + '\r' + 'hey' + (7 * ' ')
+
 
 class TestCollectonly(object):
     def test_collectonly_basic(self, testdir):