drop old style exception get, use str.format instead of +

src/tox/_pytestplugin.py

@@ -164,7 +164,7 @@ def getnext(self, cat):
     def expect(self, cat, messagepattern="*", invert=False):
         __tracebackhide__ = True
         if not messagepattern.startswith("*"):
-            messagepattern = "*" + messagepattern
+            messagepattern = "*{}".format(messagepattern)
         while self._index < len(self._calls):
             try:
                 call = self.getnext(cat)

src/tox/_quickstart.py

@@ -139,9 +139,8 @@ def do_prompt(map_, key, text, default=None, validator=nonempty, modificator=Non
         if validator:
             try:
                 answer = validator(answer)
-            except ValidationError:
-                err = sys.exc_info()[1]
-                print("* " + str(err))
+            except ValidationError as exception:
+                print("* {}".format(exception))
                 continue
         break
     map_[key] = modificator(answer, map_.get(key)) if modificator else answer
@@ -272,7 +271,7 @@ def parse_args():
         default=".",
         help="Custom root directory to write config to. Defaults to current directory.",
     )
-    parser.add_argument("--version", action="version", version="%(prog)s " + tox.__version__)
+    parser.add_argument("--version", action="version", version="%(prog)s {}".format(tox.__version__))
     return parser.parse_args()
 
 

src/tox/config.py

@@ -139,7 +139,8 @@ def postprocess(self, testenv_config, value):
                         name = "{}{}".format(option, name[len(option) :].strip())
                 # in case of a long option, we add an equal sign
                 for option in tox.PIP.INSTALL_LONG_OPTIONS_ARGUMENT:
-                    if name.startswith(option + " "):
+                    name_start = "{} ".format(option)
+                    if name.startswith(name_start):
                         name = "{}={}".format(option, name[len(option) :].strip())
             name = self._replace_forced_dep(name, config)
             deps.append(DepConfig(name, ixserver))
@@ -279,7 +280,7 @@ def parse_cli(args, pm):
 
 
 def feedback(msg, sysexit=False):
-    print("ERROR: " + msg, file=sys.stderr)
+    print("ERROR: {}".format(msg), file=sys.stderr)
     if sysexit:
         raise SystemExit(1)
 
@@ -1030,7 +1031,7 @@ def __init__(self, config, ini_path, ini_data):  # noqa
 
         # configure testenvs
         for name in all_envs:
-            section = testenvprefix + name
+            section = "{}{}".format(testenvprefix, name)
             factors = set(name.split("-"))
             if (
                 section in self._cfg
@@ -1055,7 +1056,7 @@ def parse_build_isolation(self, config, reader):
             name = config.isolated_build_env
             if name not in config.envconfigs:
                 config.envconfigs[name] = self.make_envconfig(
-                    name, testenvprefix + name, reader._subs, config
+                    name, "{}{}".format(testenvprefix, name), reader._subs, config
                 )
 
     def _make_thread_safe_path(self, config, attr, unique_id):
@@ -1103,7 +1104,7 @@ def make_envconfig(self, name, section, subs, config, replace=True):
             atype = env_attr.type
             try:
                 if atype in ("bool", "path", "string", "dict", "dict_setenv", "argv", "argvlist"):
-                    meth = getattr(reader, "get" + atype)
+                    meth = getattr(reader, "get{}".format(atype))
                     res = meth(env_attr.name, env_attr.default, replace=replace)
                 elif atype == "space-separated-list":
                     res = reader.getlist(env_attr.name, sep=" ")
@@ -1502,7 +1503,7 @@ def getargvlist(cls, reader, value, replace=True):
             if not line:
                 continue
             if line.endswith("\\"):
-                current_command += " " + line[:-1]
+                current_command += " {}".format(line[:-1])
                 continue
             current_command += line
 

src/tox/session.py

@@ -73,7 +73,7 @@ def show_help_ini(config):
     for env_attr in config._testenv_attr:
         tw.line(
             "{:<15} {:<8} default: {}".format(
-                env_attr.name, "<" + env_attr.type + ">", env_attr.default
+                env_attr.name, "<{}>".format(env_attr.type), env_attr.default
             ),
             bold=True,
         )
@@ -518,8 +518,8 @@ def developpkg(self, venv, setupdir):
             try:
                 venv.developpkg(setupdir, action)
                 return True
-            except tox.exception.InvocationError:
-                venv.status = sys.exc_info()[1]
+            except tox.exception.InvocationError as exception:
+                venv.status = exception
                 return False
 
     def installpkg(self, venv, path):
@@ -535,8 +535,8 @@ def installpkg(self, venv, path):
             try:
                 venv.installpkg(path, action)
                 return True
-            except tox.exception.InvocationError:
-                venv.status = sys.exc_info()[1]
+            except tox.exception.InvocationError as exception:
+                venv.status = exception
                 return False
 
     def subcommand_test(self):

src/tox/venv.py

@@ -180,8 +180,8 @@ def update(self, action):
         try:
             self.hook.tox_testenv_create(action=action, venv=self)
             self.just_created = True
-        except tox.exception.UnsupportedInterpreter:
-            return sys.exc_info()[1]
+        except tox.exception.UnsupportedInterpreter as exception:
+            return exception
         try:
             self.hook.tox_testenv_install_deps(action=action, venv=self)
         except tox.exception.InvocationError as exception:

tests/unit/test_config.py

@@ -2041,9 +2041,8 @@ def test_passing_no_argument(self, newconfig):
         args = ["--hashseed"]
         try:
             self._check_testenv(newconfig, "", args=args)
-        except SystemExit:
-            e = sys.exc_info()[1]
-            assert e.code == 2
+        except SystemExit as exception:
+            assert exception.code == 2
             return
         assert False  # getting here means we failed the test.