Fix readline._histline for Python 3

`unicode` is `str` here, and resulted in:

> TypeError: decoding str is not supported

Author: blueyed

pyrepl/readline.py

@@ -34,7 +34,9 @@
 from pyrepl.unix_console import UnixConsole, _error
 try:
     unicode
+    PY3 = False
 except NameError:
+    PY3 = True
     unicode = str
     unichr = chr
     basestring = bytes, str
@@ -207,8 +209,9 @@ def raw_input(self, prompt=''):
         reader.ps1 = prompt
 
         ret = reader.readline(startup_hook=self.startup_hook)
-        if sys.version_info < (3, ):
+        if not PY3:
             return ret
+
         # Unicode/str is required for Python 3 (3.5.2).
         # Ref: https://bitbucket.org/pypy/pyrepl/issues/20/#comment-30647029
         return unicode(ret, ENCODING)
@@ -247,6 +250,9 @@ def get_completer_delims(self):
 
     def _histline(self, line):
         line = line.rstrip('\n')
+        if PY3:
+            return line
+
         try:
             return unicode(line, ENCODING)
         except UnicodeDecodeError:   # bah, silently fall back...

testing/test_readline.py

@@ -1,8 +1,17 @@
-from pyrepl.readline import _ReadlineWrapper
 import os
 import pty
 import sys
 
+import pytest
+from pyrepl.readline import _ReadlineWrapper
+
+
+@pytest.fixture
+def readline_wrapper():
+    master, slave = pty.openpty()
+    return _ReadlineWrapper(slave, slave)
+
+
 if sys.version_info < (3, ):
     bytes_type = str
     unicode_type = unicode  # noqa: F821
@@ -43,3 +52,17 @@ def test_raw_input():
     else:
         assert result == 'input'
         assert isinstance(result, unicode_type)
+
+
+def test_read_history_file(readline_wrapper, tmp_path):
+    histfile = tmp_path / "history"
+    histfile.touch()
+
+    assert readline_wrapper.reader is None
+
+    readline_wrapper.read_history_file(str(histfile))
+    assert readline_wrapper.reader.history == []
+
+    histfile.write_bytes(b"foo\nbar\n")
+    readline_wrapper.read_history_file(str(histfile))
+    assert readline_wrapper.reader.history == ["foo", "bar"]