Fix #274: Py2 vs. Py3 incompatibility

This fixes problems between different string types. In Python2
str vs. unicode and in Python3 str vs. bytes.

* Add some code from six project
* Suppress two flake8 issues (false positives)

Author: tomschr

semver.py

@@ -10,6 +10,10 @@
 import warnings
 
 
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+
+
 __version__ = "2.10.2"
 __author__ = "Kostiantyn Rybnikov"
 __author_email__ = "k-bx@k-bx.com"
@@ -60,6 +64,53 @@ def cmp(a, b):
         return (a > b) - (a < b)
 
 
+if PY3:  # pragma: no cover
+    string_types = str, bytes
+    text_type = str
+    binary_type = bytes
+
+    def b(s):
+        return s.encode("latin-1")
+
+    def u(s):
+        return s
+
+
+else:  # pragma: no cover
+    string_types = unicode, str
+    text_type = unicode
+    binary_type = str
+
+    def b(s):
+        return s
+
+    # Workaround for standalone backslash
+    def u(s):
+        return unicode(s.replace(r"\\", r"\\\\"), "unicode_escape")
+
+
+def ensure_str(s, encoding="utf-8", errors="strict"):
+    # Taken from six project
+    """
+    Coerce *s* to `str`.
+
+    For Python 2:
+      - `unicode` -> encoded to `str`
+      - `str` -> `str`
+
+    For Python 3:
+      - `str` -> `str`
+      - `bytes` -> decoded to `str`
+    """
+    if not isinstance(s, (text_type, binary_type)):
+        raise TypeError("not expecting type '%s'" % type(s))
+    if PY2 and isinstance(s, text_type):
+        s = s.encode(encoding, errors)
+    elif PY3 and isinstance(s, binary_type):
+        s = s.decode(encoding, errors)
+    return s
+
+
 def deprecated(func=None, replace=None, version=None, category=DeprecationWarning):
     """
     Decorates a function to output a deprecation warning.
@@ -144,7 +195,7 @@ def comparator(operator):
 
     @wraps(operator)
     def wrapper(self, other):
-        comparable_types = (VersionInfo, dict, tuple, list, str)
+        comparable_types = (VersionInfo, dict, tuple, list, text_type, binary_type)
         if not isinstance(other, comparable_types):
             raise TypeError(
                 "other type %r must be in %r" % (type(other), comparable_types)
@@ -423,7 +474,7 @@ def compare(self, other):
         0
         """
         cls = type(self)
-        if isinstance(other, str):
+        if isinstance(other, string_types):
             other = cls.parse(other)
         elif isinstance(other, dict):
             other = cls(**other)
@@ -651,7 +702,7 @@ def parse(version):
         VersionInfo(major=3, minor=4, patch=5, \
 prerelease='pre.2', build='build.4')
         """
-        match = VersionInfo._REGEX.match(version)
+        match = VersionInfo._REGEX.match(ensure_str(version))
         if match is None:
             raise ValueError("%s is not valid SemVer string" % version)
 
@@ -825,7 +876,7 @@ def max_ver(ver1, ver2):
     >>> semver.max_ver("1.0.0", "2.0.0")
     '2.0.0'
     """
-    if isinstance(ver1, str):
+    if isinstance(ver1, string_types):
         ver1 = VersionInfo.parse(ver1)
     elif not isinstance(ver1, VersionInfo):
         raise TypeError()

setup.cfg

@@ -13,6 +13,7 @@ addopts =
 
 [flake8]
 max-line-length = 88
+ignore = F821,W503
 exclude =
     .env,
     .eggs,

test_py2.py

@@ -0,0 +1,102 @@
+import pytest
+import sys
+
+import semver
+
+
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+
+
+def ensure_binary(s, encoding="utf-8", errors="strict"):
+    """Coerce **s** to six.binary_type.
+
+    For Python 2:
+      - `unicode` -> encoded to `str`
+      - `str` -> `str`
+
+    For Python 3:
+      - `str` -> encoded to `bytes`
+      - `bytes` -> `bytes`
+    """
+    if isinstance(s, semver.text_type):
+        return s.encode(encoding, errors)
+    elif isinstance(s, semver.binary_type):
+        return s
+    else:
+        raise TypeError("not expecting type '%s'" % type(s))
+
+
+def test_should_work_with_string_and_unicode():
+    result = semver.compare(semver.u("1.1.0"), semver.b("1.2.2"))
+    assert result == -1
+    result = semver.compare(semver.b("1.1.0"), semver.u("1.2.2"))
+    assert result == -1
+
+
+class TestEnsure:
+    # From six project
+    # grinning face emoji
+    UNICODE_EMOJI = semver.u("\U0001F600")
+    BINARY_EMOJI = b"\xf0\x9f\x98\x80"
+
+    def test_ensure_binary_raise_type_error(self):
+        with pytest.raises(TypeError):
+            semver.ensure_str(8)
+
+    def test_errors_and_encoding(self):
+        ensure_binary(self.UNICODE_EMOJI, encoding="latin-1", errors="ignore")
+        with pytest.raises(UnicodeEncodeError):
+            ensure_binary(self.UNICODE_EMOJI, encoding="latin-1", errors="strict")
+
+    def test_ensure_binary_raise(self):
+        converted_unicode = ensure_binary(
+            self.UNICODE_EMOJI, encoding="utf-8", errors="strict"
+        )
+        converted_binary = ensure_binary(
+            self.BINARY_EMOJI, encoding="utf-8", errors="strict"
+        )
+        if semver.PY2:
+            # PY2: unicode -> str
+            assert converted_unicode == self.BINARY_EMOJI and isinstance(
+                converted_unicode, str
+            )
+            # PY2: str -> str
+            assert converted_binary == self.BINARY_EMOJI and isinstance(
+                converted_binary, str
+            )
+        else:
+            # PY3: str -> bytes
+            assert converted_unicode == self.BINARY_EMOJI and isinstance(
+                converted_unicode, bytes
+            )
+            # PY3: bytes -> bytes
+            assert converted_binary == self.BINARY_EMOJI and isinstance(
+                converted_binary, bytes
+            )
+
+    def test_ensure_str(self):
+        converted_unicode = semver.ensure_str(
+            self.UNICODE_EMOJI, encoding="utf-8", errors="strict"
+        )
+        converted_binary = semver.ensure_str(
+            self.BINARY_EMOJI, encoding="utf-8", errors="strict"
+        )
+        if PY2:
+            # PY2: unicode -> str
+            assert converted_unicode == self.BINARY_EMOJI and isinstance(
+                converted_unicode, str
+            )
+            # PY2: str -> str
+            assert converted_binary == self.BINARY_EMOJI and isinstance(
+                converted_binary, str
+            )
+        else:
+            # PY3: str -> str
+            assert converted_unicode == self.UNICODE_EMOJI and isinstance(
+                converted_unicode, str
+            )
+            # PY3: bytes -> str
+            assert converted_binary == self.UNICODE_EMOJI and isinstance(
+                converted_unicode, str
+            )