Restores compatibility shim with platform.linux_distribution

distro#230 introduced proper support for os-release `VERSION_CODENAME`
attribute but broke compatibility shim with (now defunct)
`platform.linux_distribution` as the third tuple member (codename) were
not taken from `VERSION` os-release attribute anymore.

Closes #238.

Author: Samuel FORESTIER

src/distro/distro.py

@@ -151,7 +151,8 @@ def linux_distribution(full_distribution_name: bool = True) -> Tuple[str, str, s
 
     * ``version``:  The result of :func:`distro.version`.
 
-    * ``codename``:  The result of :func:`distro.codename`.
+    * ``codename``:  The extra item (usually in parentheses) after the
+      os-release version number, or the result of :func:`distro.codename`.
 
     The interface of this function is compatible with the original
     :py:func:`platform.linux_distribution` function, supporting a subset of
@@ -768,7 +769,7 @@ def linux_distribution(
         return (
             self.name() if full_distribution_name else self.id(),
             self.version(),
-            self.codename(),
+            self._os_release_info.get("release_codename") or self.codename(),
         )
 
     def id(self) -> str:
@@ -1062,6 +1063,13 @@ def _parse_os_release_content(lines: TextIO) -> Dict[str, str]:
                 # Ignore any tokens that are not variable assignments
                 pass
 
+        if "version" in props:
+            # extract release codename (if any) from version attribute
+            match = re.search(r"\((\D+)\)|,\s*(\D+)", props["version"])
+            if match:
+                release_codename = match.group(1) or match.group(2)
+                props["codename"] = props["release_codename"] = release_codename
+
         if "version_codename" in props:
             # os-release added a version_codename field.  Use that in
             # preference to anything else Note that some distros purposefully
@@ -1071,16 +1079,6 @@ def _parse_os_release_content(lines: TextIO) -> Dict[str, str]:
         elif "ubuntu_codename" in props:
             # Same as above but a non-standard field name used on older Ubuntus
             props["codename"] = props["ubuntu_codename"]
-        elif "version" in props:
-            # If there is no version_codename, parse it from the version
-            match = re.search(r"(\(\D+\))|,(\s+)?\D+", props["version"])
-            if match:
-                codename = match.group()
-                codename = codename.strip("()")
-                codename = codename.strip(",")
-                codename = codename.strip()
-                # codename appears within paranthese.
-                props["codename"] = codename
 
         return props
 

tests/test_distro.py

@@ -1833,6 +1833,9 @@ def setup_method(self, test_method: FunctionType) -> None:
         self.ubuntu14_os_release = os.path.join(
             DISTROS_DIR, "ubuntu14", "etc", "os-release"
         )
+        self.fedora30_os_release = os.path.join(
+            DISTROS_DIR, "fedora30", "etc", "os-release"
+        )
 
     def test_info(self) -> None:
         _distro = distro.LinuxDistribution(
@@ -1905,6 +1908,12 @@ def test_linux_distribution(self) -> None:
         i = _distro.linux_distribution()
         assert i == ("Ubuntu", "14.04", "Trusty Tahr")
 
+        _distro = distro.LinuxDistribution(
+            include_lsb=False, os_release_file=self.fedora30_os_release
+        )
+        i = _distro.linux_distribution()
+        assert i == ("Fedora", "30", "Thirty")
+
     def test_linux_distribution_full_false(self) -> None:
         _distro = distro.LinuxDistribution(
             include_lsb=False, os_release_file=self.ubuntu14_os_release