Migrate from % syntax or bad format() syntax to fstring

We can do that in python 3.6

3 files changed, 5 insertions, 18 deletions

diff --git a/pylint/checkers/base.py b/pylint/checkers/base.py
index 647c201d9..0a836de4c 100644
--- a/pylint/checkers/base.py
+++ b/pylint/checkers/base.py
@@ -1331,7 +1331,6 @@ class BasicChecker(_BasicChecker):
                 isinstance(value, astroid.Instance)
                 and value.qname() in DEFAULT_ARGUMENT_SYMBOLS
             ):
-
                 if value is default:
                     msg = DEFAULT_ARGUMENT_SYMBOLS[value.qname()]
                 elif isinstance(value, astroid.Instance) or is_iterable(value):
@@ -1350,10 +1349,7 @@ class BasicChecker(_BasicChecker):
                         msg = f"{default.as_string()} ({value.qname()})"
                 else:
                     # this argument is a name
-                    msg = "{} ({})".format(
-                        default.as_string(),
-                        DEFAULT_ARGUMENT_SYMBOLS[value.qname()],
-                    )
+                    msg = f"{default.as_string()} ({DEFAULT_ARGUMENT_SYMBOLS[value.qname()]})"
                 self.add_message("dangerous-default-value", node=node, args=(msg,))
 
     @utils.check_messages("unreachable", "lost-exception")
@@ -2437,14 +2433,9 @@ class ComparisonChecker(_BasicChecker):
         if checking_for_absence:
             absence_text = "not "
         if nan_left:
-            suggestion = "'{}math.isnan({})'".format(
-                absence_text, right_value.as_string()
-            )
+            suggestion = f"'{absence_text}math.isnan({right_value.as_string()})'"
         else:
-            suggestion = "'{}math.isnan({})'".format(
-                absence_text, left_value.as_string()
-            )
-
+            suggestion = f"'{absence_text}math.isnan({left_value.as_string()})'"
         self.add_message(
             "nan-comparison",
             node=root_node,
diff --git a/pylint/checkers/classes.py b/pylint/checkers/classes.py
index aada6bbf3..83abf758f 100644
--- a/pylint/checkers/classes.py
+++ b/pylint/checkers/classes.py
@@ -1604,7 +1604,7 @@ a metaclass class method.",
                 valid = repr(config[0])
             else:
                 valid = ", ".join(repr(v) for v in config[:-1])
-                valid = "{} or {!r}".format(valid, config[-1])
+                valid = f"{valid} or {config[-1]!r}"
             self.add_message(message, args=(method_name, valid), node=node)
 
     def _check_bases_classes(self, node):
diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index 01cf8ecbd..1e96f1b4e 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -1643,11 +1643,7 @@ class VariablesChecker(BaseChecker):
                     return
                 if isinstance(stmt, astroid.ImportFrom):
                     if asname is not None:
-                        msg = "{} imported from {} as {}".format(
-                            qname,
-                            stmt.modname,
-                            asname,
-                        )
+                        msg = f"{qname} imported from {stmt.modname} as {asname}"
                     else:
                         msg = f"{name} imported from {stmt.modname}"
                     self.add_message("unused-import", args=msg, node=stmt)