chore: Upgrade Python syntax with pyupgrade

Run with the following pre-commit configuration:

```
repos:
  - repo: https://github.com/asottile/pyupgrade
    rev: v3.1.0
    hooks:
      - id: pyupgrade
        args: [ "--py3-plus", "--py36-plus", "--py37-plus" ]
```

The rationale for every change can be found at https://github.com/asottile/pyupgrade

django_migration_linter/cache.py

@@ -6,20 +6,20 @@ class Cache(dict):
     def __init__(self, django_folder, database, cache_path):
         self.filename = os.path.join(
             cache_path,
-            "{0}_{1}.pickle".format(django_folder.replace(os.sep, "_"), database),
+            "{}_{}.pickle".format(django_folder.replace(os.sep, "_"), database),
         )
 
         if not os.path.exists(os.path.dirname(self.filename)):
             os.makedirs(os.path.dirname(self.filename))
 
-        super(Cache, self).__init__()
+        super().__init__()
 
     def load(self):
         try:
             with open(self.filename, "rb") as f:
                 tmp_dict = pickle.load(f)
                 self.update(tmp_dict)
-        except IOError:
+        except OSError:
             pass
 
     def save(self):

django_migration_linter/management/commands/lintmigrations.py

@@ -19,7 +19,7 @@ from ..utils import (
 CONFIG_NAME = "django_migration_linter"
 PYPROJECT_TOML = "pyproject.toml"
 DEFAULT_CONFIG_FILES = (
-    ".{}.cfg".format(CONFIG_NAME),
+    f".{CONFIG_NAME}.cfg",
     "setup.cfg",
     "tox.ini",
 )

django_migration_linter/management/commands/makemigrations.py

@@ -34,7 +34,7 @@ class Command(MakeMigrationsCommand):
     help = "Creates new migration(s) for apps and lints them."
 
     def add_arguments(self, parser):
-        super(Command, self).add_arguments(parser)
+        super().add_arguments(parser)
         parser.add_argument(
             "--lint",
             action="store_true",
@@ -49,10 +49,10 @@ class Command(MakeMigrationsCommand):
         self.warnings_as_errors = options["warnings_as_errors"]
         self.sql_analyser = options["sql_analyser"]
         configure_logging(options["verbosity"])
-        return super(Command, self).handle(*app_labels, **options)
+        return super().handle(*app_labels, **options)
 
     def write_migration_files(self, changes):
-        super(Command, self).write_migration_files(changes)
+        super().write_migration_files(changes)
 
         if (
             not getattr(settings, "MIGRATION_LINTER_OVERRIDE_MAKEMIGRATIONS", False)

django_migration_linter/migration_linter.py

@@ -36,7 +36,7 @@ class MessageType(Enum):
         return list(map(lambda c: c.value, MessageType))
 
 
-class MigrationLinter(object):
+class MigrationLinter:
     def __init__(
         self,
         path=None,
@@ -263,17 +263,17 @@ class MigrationLinter(object):
         if lint_result.value in self.quiet:
             return
         if not self.no_output:
-            print("({0}, {1})... {2}".format(app_label, migration_name, msg))
+            print(f"({app_label}, {migration_name})... {msg}")
 
     def print_errors(self, errors):
         if MessageType.ERROR.value in self.quiet:
             return
         for err in errors:
-            error_str = "\t{0}".format(err["msg"])
+            error_str = "\t{}".format(err["msg"])
             if err.get("table"):
-                error_str += " (table: {0}".format(err["table"])
+                error_str += " (table: {}".format(err["table"])
                 if err.get("column"):
-                    error_str += ", column: {0}".format(err["column"])
+                    error_str += ", column: {}".format(err["column"])
                 error_str += ")"
             if not self.no_output:
                 print(error_str)
@@ -291,10 +291,10 @@ class MigrationLinter(object):
         if self.no_output:
             return
         print("*** Summary ***")
-        print("Valid migrations: {}/{}".format(self.nb_valid, self.nb_total))
+        print(f"Valid migrations: {self.nb_valid}/{self.nb_total}")
-        print("Erroneous migrations: {}/{}".format(self.nb_erroneous, self.nb_total))
+        print(f"Erroneous migrations: {self.nb_erroneous}/{self.nb_total}")
-        print("Migrations with warnings: {}/{}".format(self.nb_warnings, self.nb_total))
+        print(f"Migrations with warnings: {self.nb_warnings}/{self.nb_total}")
-        print("Ignored migrations: {}/{}".format(self.nb_ignored, self.nb_total))
+        print(f"Ignored migrations: {self.nb_ignored}/{self.nb_total}")
 
     @property
     def has_errors(self):
@@ -302,7 +302,7 @@ class MigrationLinter(object):
 
     def get_sql(self, app_label, migration_name):
         logger.info(
-            "Calling sqlmigrate command {} {}".format(app_label, migration_name)
+            f"Calling sqlmigrate command {app_label} {migration_name}"
         )
         dev_null = open(os.devnull, "w")
         try:
@@ -327,7 +327,7 @@ class MigrationLinter(object):
         from django.db.migrations.loader import MIGRATIONS_MODULE_NAME
 
         return (
-            re.search(r"/{0}/.*\.py".format(MIGRATIONS_MODULE_NAME), filename)
+            re.search(fr"/{MIGRATIONS_MODULE_NAME}/.*\.py", filename)
             and "__init__" not in filename
         )
 
@@ -343,12 +343,12 @@ class MigrationLinter(object):
 
         migrations = []
         try:
-            with open(migrations_file_path, "r") as file:
+            with open(migrations_file_path) as file:
                 for line in file:
                     if cls.is_migration_file(line):
                         app_label, name = split_migration_path(line)
                         migrations.append((app_label, name))
-        except IOError:
+        except OSError:
             logger.exception("Migrations list path not found %s", migrations_file_path)
             raise Exception("Error while reading migrations list file")
 
@@ -363,9 +363,9 @@ class MigrationLinter(object):
         migrations = []
         # Get changes since specified commit
         git_diff_command = (
-            "cd {0} && git diff --relative --name-only --diff-filter=AR {1}"
+            "cd {} && git diff --relative --name-only --diff-filter=AR {}"
         ).format(self.django_path, git_commit_id)
-        logger.info("Executing {0}".format(git_diff_command))
+        logger.info(f"Executing {git_diff_command}")
         diff_process = Popen(git_diff_command, shell=True, stdout=PIPE, stderr=PIPE)
         for line in map(clean_bytes_to_str, diff_process.stdout.readlines()):
             # Only gather lines that include added migrations
@@ -537,7 +537,7 @@ class MigrationLinter(object):
             model = model.split(".", 1)[0]
             has_get_model_call = (
                 re.search(
-                    r"{}.*= +\w+\.get_model\(".format(model),
+                    fr"{model}.*= +\w+\.get_model\(",
                     source_code,
                 )
                 is not None

django_migration_linter/sql_analyser/base.py

@@ -36,13 +36,13 @@ def has_add_unique(sql_statements, **kwargs):
 
     concerned_table = regex_result.group(1)
     table_is_added_in_transaction = any(
-        sql.startswith("CREATE TABLE {}".format(concerned_table))
+        sql.startswith(f"CREATE TABLE {concerned_table}")
         for sql in sql_statements
     )
     return not table_is_added_in_transaction
 
 
-class BaseAnalyser(object):
+class BaseAnalyser:
     base_migration_tests = [
         {
             "code": "RENAME_TABLE",

django_migration_linter/sql_analyser/postgresql.py

@@ -16,7 +16,7 @@ def has_create_index(sql_statements, **kwargs):
 
     concerned_table = regex_result.group(2)
     table_is_added_in_transaction = any(
-        sql.startswith("CREATE TABLE {}".format(concerned_table))
+        sql.startswith(f"CREATE TABLE {concerned_table}")
         for sql in sql_statements
     )
     return not table_is_added_in_transaction

django_migration_linter/utils.py

@@ -38,7 +38,7 @@ def get_migration_abspath(app_label, migration_name):
     from django.db.migrations.loader import MigrationLoader
 
     module_name, _ = MigrationLoader.migrations_module(app_label)
-    migration_path = "{}.{}".format(module_name, migration_name)
+    migration_path = f"{module_name}.{migration_name}"
     migration_module = import_module(migration_path)
 
     migration_file = migration_module.__file__

setup.py

@@ -10,7 +10,7 @@ PROJECT_DIR = path.abspath(path.dirname(__file__))
 def get_version():
     constants = path.join(PROJECT_DIR, "django_migration_linter", "constants.py")
     _version_re = re.compile(r"__version__\s+=\s+(?P<version>.*)")
-    with open(constants, "r") as f:
+    with open(constants) as f:
         match = _version_re.search(f.read())
         version = match.group("version") if match is not None else '"unknown"'
     return str(ast.literal_eval(version))

tests/functional/test_migration_linter.py

@@ -8,7 +8,7 @@ from django_migration_linter import MigrationLinter
 from tests import fixtures
 
 
-class BaseBackwardCompatibilityDetection(object):
+class BaseBackwardCompatibilityDetection:
     def setUp(self, *args, **kwargs):
         self.database = next(iter(self.databases))
         self.test_project_path = os.path.dirname(settings.BASE_DIR)
@@ -24,7 +24,7 @@ class BaseBackwardCompatibilityDetection(object):
             "app_unique_together",
             database=self.database,
         )
-        return super(BaseBackwardCompatibilityDetection, self).setUp(*args, **kwargs)
+        return super().setUp(*args, **kwargs)
 
     def _test_linter_finds_errors(self, app=None, commit_id=None):
         linter = self._launch_linter(app, commit_id)

tests/test_project/app_add_not_null_column_followed_by_default/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:54
 
 

tests/test_project/app_add_not_null_column_followed_by_default/migrations/0002_a_not_null_field.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:55
 
 

tests/test_project/app_add_not_null_column_followed_by_default/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 

tests/test_project/app_alter_column/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:56
 
 

tests/test_project/app_alter_column/migrations/0002_auto_20190414_1456.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:56
 
 

tests/test_project/app_alter_column/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 

tests/test_project/app_create_table_with_not_null_column/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:59
 
 

tests/test_project/app_create_table_with_not_null_column/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 

tests/test_project/app_drop_column/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:59
 
 

tests/test_project/app_drop_column/migrations/0002_remove_a_field_b.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:59
 
 

tests/test_project/app_drop_column/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 

tests/test_project/app_drop_table/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 14:59
 
 

tests/test_project/app_drop_table/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 # class A(models.Model):

tests/test_project/app_rename_column/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 15:02
 
 

tests/test_project/app_rename_column/migrations/0002_auto_20190414_1502.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 15:02
 
 

tests/test_project/app_rename_column/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 

tests/test_project/app_rename_table/migrations/0001_initial.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 15:00
 
 

tests/test_project/app_rename_table/migrations/0002_auto_20190414_1500.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.18 on 2019-04-14 15:00
 
 

tests/test_project/app_rename_table/models.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-
-
 from django.db import models
 
 

tests/unit/test_sql_analyser.py

@@ -19,10 +19,10 @@ class SqlAnalyserTestCase(unittest.TestCase):
 
     def assertValidSql(self, sql, allow_warnings=False):
         errors, _, warnings = self.analyse_sql(sql)
-        self.assertEqual(0, len(errors), "Found errors in sql: {}".format(errors))
+        self.assertEqual(0, len(errors), f"Found errors in sql: {errors}")
         if not allow_warnings:
             self.assertEqual(
-                0, len(warnings), "Found warnings in sql: {}".format(errors)
+                0, len(warnings), f"Found warnings in sql: {errors}"
             )
 
     def assertBackwardIncompatibleSql(self, sql, code=None):