Modernize code to Python 3.6+ (#1229)

1. `class A(object)` can be written as `class A:`
2. replace `dict([…])` and `set([…])` with `{…}`
3. use f-strings or compact `.format`
4. use `yield from` instead of `yield` in a `for` loop
5. import `mock` from `unittest`
6. expect `OSError` instead of `IOError` or `select` error
7. use Python3 defaults for file reading or `super()`
8. remove redundant parenthesis (keep those in tuples though)
9. shorten set intersection instead of creating lists
10. backslashes in strings do not have to be escaped if prepended with `r`

31 files changed, 368 insertions, 417 deletions

diff --git a/AUTHORS b/AUTHORS
index b7f50adf..ab9ce384 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -115,6 +115,7 @@ Contributors:
     * Jan Brun Rasmussen (janbrunrasmussen)
     * Kevin Marsh (kevinmarsh)
     * Eero Ruohola (ruohola)
+    * Miroslav Šedivý (eumiro)
 
 Creator:
 --------
diff --git a/pgcli/completion_refresher.py b/pgcli/completion_refresher.py
index cf0879fd..3e847b09 100644
--- a/pgcli/completion_refresher.py
+++ b/pgcli/completion_refresher.py
@@ -6,7 +6,7 @@ from .pgcompleter import PGCompleter
 from .pgexecute import PGExecute
 
 
-class CompletionRefresher(object):
+class CompletionRefresher:
 
     refreshers = OrderedDict()
 
@@ -141,7 +141,7 @@ def refresh_casing(completer, executor):
         with open(casing_file, "w") as f:
             f.write(casing_prefs)
     if os.path.isfile(casing_file):
-        with open(casing_file, "r") as f:
+        with open(casing_file) as f:
             completer.extend_casing([line.strip() for line in f])
 
 
diff --git a/pgcli/magic.py b/pgcli/magic.py
index f58f4150..c2b60aa0 100644
--- a/pgcli/magic.py
+++ b/pgcli/magic.py
@@ -43,7 +43,7 @@ def pgcli_line_magic(line):
         conn._pgcli = pgcli
 
     # For convenience, print the connection alias
-    print("Connected: {}".format(conn.name))
+    print(f"Connected: {conn.name}")
 
     try:
         pgcli.run_cli()
diff --git a/pgcli/main.py b/pgcli/main.py
index b1468985..7ab973a2 100644
--- a/pgcli/main.py
+++ b/pgcli/main.py
@@ -122,7 +122,7 @@ class PgCliQuitError(Exception):
     pass
 
 
-class PGCli(object):
+class PGCli:
     default_prompt = "\\u@\\h:\\d> "
     max_len_prompt = 30
 
@@ -325,11 +325,11 @@ class PGCli(object):
             if pattern not in TabularOutputFormatter().supported_formats:
                 raise ValueError()
             self.table_format = pattern
-            yield (None, None, None, "Changed table format to {}".format(pattern))
+            yield (None, None, None, f"Changed table format to {pattern}")
         except ValueError:
-            msg = "Table format {} not recognized. Allowed formats:".format(pattern)
+            msg = f"Table format {pattern} not recognized. Allowed formats:"
             for table_type in TabularOutputFormatter().supported_formats:
-                msg += "\n\t{}".format(table_type)
+                msg += f"\n\t{table_type}"
             msg += "\nCurrently set to: %s" % self.table_format
             yield (None, None, None, msg)
 
@@ -386,7 +386,7 @@ class PGCli(object):
         try:
             with open(os.path.expanduser(pattern), encoding="utf-8") as f:
                 query = f.read()
-        except IOError as e:
+        except OSError as e:
             return [(None, None, None, str(e), "", False, True)]
 
         if self.destructive_warning and confirm_destructive_query(query) is False:
@@ -407,7 +407,7 @@ class PGCli(object):
         if not os.path.isfile(filename):
             try:
                 open(filename, "w").close()
-            except IOError as e:
+            except OSError as e:
                 self.output_file = None
                 message = str(e) + "\nFile output disabled"
                 return [(None, None, None, message, "", False, True)]
@@ -479,7 +479,7 @@ class PGCli(object):
         service_config, file = parse_service_info(service)
         if service_config is None:
             click.secho(
-                "service '%s' was not found in %s" % (service, file), err=True, fg="red"
+                f"service '{service}' was not found in {file}", err=True, fg="red"
             )
             exit(1)
         self.connect(
@@ -515,7 +515,7 @@ class PGCli(object):
             passwd = os.environ.get("PGPASSWORD", "")
 
         # Find password from store
-        key = "%s@%s" % (user, host)
+        key = f"{user}@{host}"
         keyring_error_message = dedent(
             """\
             {}
@@ -677,7 +677,7 @@ class PGCli(object):
                             click.echo(text, file=f)
                             click.echo("\n".join(output), file=f)
                             click.echo("", file=f)  # extra newline
-                    except IOError as e:
+                    except OSError as e:
                         click.secho(str(e), err=True, fg="red")
                 else:
                     if output:
@@ -753,11 +753,7 @@ class PGCli(object):
                     while self.watch_command:
                         try:
                             query = self.execute_command(self.watch_command)
-                            click.echo(
-                                "Waiting for {0} seconds before repeating".format(
-                                    timing
-                                )
-                            )
+                            click.echo(f"Waiting for {timing} seconds before repeating")
                             sleep(timing)
                         except KeyboardInterrupt:
                             self.watch_command = None
@@ -1049,7 +1045,7 @@ class PGCli(object):
             str(self.pgexecute.port) if self.pgexecute.port is not None else "5432",
         )
         string = string.replace("\\i", str(self.pgexecute.pid) or "(none)")
-        string = string.replace("\\#", "#" if (self.pgexecute.superuser) else ">")
+        string = string.replace("\\#", "#" if self.pgexecute.superuser else ">")
         string = string.replace("\\n", "\n")
         return string
 
@@ -1384,7 +1380,7 @@ def is_mutating(status):
     if not status:
         return False
 
-    mutating = set(["insert", "update", "delete"])
+    mutating = {"insert", "update", "delete"}
     return status.split(None, 1)[0].lower() in mutating
 
 
diff --git a/pgcli/packages/parseutils/meta.py b/pgcli/packages/parseutils/meta.py
index 108c01a3..333cab55 100644
--- a/pgcli/packages/parseutils/meta.py
+++ b/pgcli/packages/parseutils/meta.py
@@ -50,7 +50,7 @@ def parse_defaults(defaults_string):
     yield current
 
 
-class FunctionMetadata(object):
+class FunctionMetadata:
     def __init__(
         self,
         schema_name,
diff --git a/pgcli/packages/parseutils/tables.py b/pgcli/packages/parseutils/tables.py
index 0ec3e693..aaa676cc 100644
--- a/pgcli/packages/parseutils/tables.py
+++ b/pgcli/packages/parseutils/tables.py
@@ -42,8 +42,7 @@ def extract_from_part(parsed, stop_at_punctuation=True):
     for item in parsed.tokens:
         if tbl_prefix_seen:
             if is_subselect(item):
-                for x in extract_from_part(item, stop_at_punctuation):
-                    yield x
+                yield from extract_from_part(item, stop_at_punctuation)
             elif stop_at_punctuation and item.ttype is Punctuation:
                 return
             # An incomplete nested select won't be recognized correctly as a
diff --git a/pgcli/packages/prioritization.py b/pgcli/packages/prioritization.py
index e92dcbb6..f5a9cb57 100644
--- a/pgcli/packages/prioritization.py
+++ b/pgcli/packages/prioritization.py
@@ -16,10 +16,10 @@ def _compile_regex(keyword):
 
 
 keywords = get_literals("keywords")
-keyword_regexs = dict((kw, _compile_regex(kw)) for kw in keywords)
+keyword_regexs = {kw: _compile_regex(kw) for kw in keywords}
 
 
-class PrevalenceCounter(object):
+class PrevalenceCounter:
     def __init__(self):
         self.keyword_counts = defaultdict(int)
         self.name_counts = defaultdict(int)
diff --git a/pgcli/packages/sqlcompletion.py b/pgcli/packages/sqlcompletion.py
index 6ef88595..63053018 100644
--- a/pgcli/packages/sqlcompletion.py
+++ b/pgcli/packages/sqlcompletion.py
@@ -47,7 +47,7 @@ Alias = namedtuple("Alias", ["aliases"])
 Path = namedtuple("Path", [])
 
 
-class SqlStatement(object):
+class SqlStatement:
     def __init__(self, full_text, text_before_cursor):
         self.identifier = None
         self.word_before_cursor = word_before_cursor = last_word(
diff --git a/pgcli/pgcompleter.py b/pgcli/pgcompleter.py
index 9c95a01c..79be274e 100644
--- a/pgcli/pgcompleter.py
+++ b/pgcli/pgcompleter.py
@@ -83,7 +83,7 @@ class PGCompleter(Completer):
     reserved_words = set(get_literals("reserved"))
 
     def __init__(self, smart_completion=True, pgspecial=None, settings=None):
-        super(PGCompleter, self).__init__()
+        super().__init__()
         self.smart_completion = smart_completion
         self.pgspecial = pgspecial
         self.prioritizer = PrevalenceCounter()
@@ -177,7 +177,7 @@ class PGCompleter(Completer):
         :return:
         """
         # casing should be a dict {lowercasename:PreferredCasingName}
-        self.casing = dict((word.lower(), word) for word in words)
+        self.casing = {word.lower(): word for word in words}
 
     def extend_relations(self, data, kind):
         """extend metadata for tables or views.
@@ -279,8 +279,8 @@ class PGCompleter(Completer):
             fk = ForeignKey(
                 parentschema, parenttable, parcol, childschema, childtable, childcol
             )
-            childcolmeta.foreignkeys.append((fk))
-            parcolmeta.foreignkeys.append((fk))
+            childcolmeta.foreignkeys.append(fk)
+            parcolmeta.foreignkeys.append(fk)
 
     def extend_datatypes(self, type_data):
 
@@ -424,7 +424,7 @@ class PGCompleter(Completer):
                 # the same priority as unquoted names.
                 lexical_priority = (
                     tuple(
-                        0 if c in (" _") else -ord(c)
+                        0 if c in " _" else -ord(c)
                         for c in self.unescape_name(item.lower())
                     )
                     + (1,)
@@ -517,9 +517,9 @@ class PGCompleter(Completer):
             # require_last_table is used for 'tb11 JOIN tbl2 USING (...' which should
             # suggest only columns that appear in the last table and one more
             ltbl = tables[-1].ref
-            other_tbl_cols = set(
+            other_tbl_cols = {
                 c.name for t, cs in scoped_cols.items() if t.ref != ltbl for c in cs
-            )
+            }
             scoped_cols = {
                 t: [col for col in cols if col.name in other_tbl_cols]
                 for t, cols in scoped_cols.items()
@@ -574,7 +574,7 @@ class PGCompleter(Completer):
         tbls - TableReference iterable of tables already in query
         """
         tbl = self.case(tbl)
-        tbls = set(normalize_ref(t.ref) for t in tbls)
+        tbls = {normalize_ref(t.ref) for t in tbls}
         if self.generate_aliases:
             tbl = generate_alias(self.unescape_name(tbl))
         if normalize_ref(tbl) not in tbls:
@@ -589,10 +589,10 @@ class PGCompleter(Completer):
         tbls = suggestion.table_refs
         cols = self.populate_scoped_cols(tbls)
         # Set up some data structures for efficient access
-        qualified = dict((normalize_ref(t.ref), t.schema) for t in tbls)
-        ref_prio = dict((normalize_ref(t.ref), n) for n, t in enumerate(tbls))
-        refs = set(normalize_ref(t.ref) for t in tbls)
-        other_tbls = set((t.schema, t.name) for t in list(cols)[:-1])
+        qualified = {normalize_ref(t.ref): t.schema for t in tbls}
+        ref_prio = {normalize_ref(t.ref): n for n, t in enumerate(tbls)}
+        refs = {normalize_ref(t.ref) for t in tbls}
+        other_tbls = {(t.schema, t.name) for t in list(cols)[:-1]}
         joins = []
         # Iterate over FKs in existing tables to find potential joins
         fks = (
@@ -667,7 +667,7 @@ class PGCompleter(Completer):
             return d
 
         # Tables that are closer to the cursor get higher prio
-        ref_prio = dict((tbl.ref, num) for num, tbl in enumerate(suggestion.table_refs))
+        ref_prio = {tbl.ref: num for num, tbl in enumerate(suggestion.table_refs)}
         # Map (schema, table, col) to tables
         coldict = list_dict(
             ((t.schema, t.name, c.name), t) for t, c in cols if t.ref != lref
@@ -721,9 +721,7 @@ class PGCompleter(Completer):
         # Function overloading means we way have multiple functions of the same
         # name at this point, so keep unique names only
         all_functions = self.populate_functions(suggestion.schema, filt)
-        funcs = set(
-            self._make_cand(f, alias, suggestion, arg_mode) for f in all_functions
-        )
+        funcs = {self._make_cand(f, alias, suggestion, arg_mode) for f in all_functions}
 
         matches = self.find_matches(word_before_cursor, funcs, meta="function")
 
@@ -953,7 +951,7 @@ class PGCompleter(Completer):
         :return: {TableReference:{colname:ColumnMetaData}}
 
         """
-        ctes = dict((normalize_ref(t.name), t.columns) for t in local_tbls)
+        ctes = {normalize_ref(t.name): t.columns for t in local_tbls}
         columns = OrderedDict()
         meta = self.dbmetadata
 
diff --git a/pgcli/pgexecute.py b/pgcli/pgexecute.py
index d34bf26d..5cba7845 100644
--- a/pgcli/pgexecute.py
+++ b/pgcli/pgexecute.py
@@ -49,7 +49,7 @@ def _wait_select(conn):
             conn.cancel()
             # the loop will be broken by a server error
             continue
-        except select.error as e:
+        except OSError as e:
             errno = e.args[0]
             if errno != 4:
                 raise
@@ -127,7 +127,7 @@ def register_hstore_typecaster(conn):
             pass
 
 
-class PGExecute(object):
+class PGExecute:
 
     # The boolean argument to the current_schemas function indicates whether
     # implicit schemas, e.g. pg_catalog
@@ -485,7 +485,7 @@ class PGExecute(object):
             try:
                 cur.execute(sql, (spec,))
             except psycopg2.ProgrammingError:
-                raise RuntimeError("View {} does not exist.".format(spec))
+                raise RuntimeError(f"View {spec} does not exist.")
             result = cur.fetchone()
             view_type = "MATERIALIZED" if result[2] == "m" else ""
             return template.format(*result + (view_type,))
@@ -501,7 +501,7 @@ class PGExecute(object):
                 result = cur.fetchone()
                 return result[0]
             except psycopg2.ProgrammingError:
-                raise RuntimeError("Function {} does not exist.".format(spec))
+                raise RuntimeError(f"Function {spec} does not exist.")
 
     def schemata(self):
         """Returns a list of schema names in the database"""
@@ -527,21 +527,18 @@ class PGExecute(object):
             sql = cur.mogrify(self.tables_query, [kinds])
             _logger.debug("Tables Query. sql: %r", sql)
             cur.execute(sql)
-            for row in cur:
-                yield row
+            yield from cur
 
     def tables(self):
         """Yields (schema_name, table_name) tuples"""
-        for row in self._relations(kinds=["r", "p", "f"]):
-            yield row
+        yield from self._relations(kinds=["r", "p", "f"])
 
     def views(self):
         """Yields (schema_name, view_name) tuples.
 
         Includes both views and and materialized views
         """
-        for row in self._relations(kinds=["v", "m"]):
-            yield row
+        yield from self._relations(kinds=["v", "m"])
 
     def _columns(self, kinds=("r", "p", "f", "v", "m")):
         """Get column metadata for tables and views
@@ -599,16 +596,13 @@ class PGExecute(object):
             sql = cur.mogrify(columns_query, [kinds])
             _logger.debug("Columns Query. sql: %r", sql)
             cur.execute(sql)
-            for row in cur:
-                yield row
+            yield from cur
 
     def table_columns(self):
-        for row in self._columns(kinds=["r", "p", "f"]):
-            yield row
+        yield from self._columns(kinds=["r", "p", "f"])
 
     def view_columns(self):
-        for row in self._columns(kinds=["v", "m"]):
-            yield row
+        yield from self._columns(kinds=["v", "m"])
 
     def databases(self):
         with self.conn.cursor() as cur:
@@ -804,8 +798,7 @@ class PGExecute(object):
                 """
             _logger.debug("Datatypes Query. sql: %r", query)
             cur.execute(query)
-            for row in cur:
-                yield row
+            yield from cur
 
     def casing(self):
         """Yields the most common casing for names used in db functions"""
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 80e8f437..84fa6bf7 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,5 +1,4 @@
 pytest>=2.7.0
-mock>=1.0.1
 tox>=1.9.2
 behave>=1.2.4
 pexpect==3.3
diff --git a/tests/features/db_utils.py b/tests/features/db_utils.py
index f57bc3b9..6898394e 100644
--- a/tests/features/db_utils.py
+++ b/tests/features/db_utils.py
@@ -44,7 +44,7 @@ def create_cn(hostname, password, username, dbname, port):
         host=hostname, user=username, database=dbname, password=password, port=port
     )
 
-    print("Created connection: {0}.".format(cn.dsn))
+    print(f"Created connection: {cn.dsn}.")
     return cn
 
 
@@ -75,4 +75,4 @@ def close_cn(cn=None):
     """
     if cn:
         cn.close()
-        print("Closed connection: {0}.".format(cn.dsn))
+        print(f"Closed connection: {cn.dsn}.")
diff --git a/tests/features/environment.py b/tests/features/environment.py
index 049c2f23..a8b3e26a 100644
--- a/tests/features/environment.py
+++ b/tests/features/environment.py
@@ -38,7 +38,7 @@ def before_all(context):
 
     vi = "_".join([str(x) for x in sys.version_info[:3]])
     db_name = context.config.userdata.get("pg_test_db", "pgcli_behave_tests")
-    db_name_full = "{0}_{1}".format(db_name, vi)
+    db_name_full = f"{db_name}_{vi}"
 
     # Store get params from config.
     context.conf = {
@@ -122,12 +122,12 @@ def before_all(context):
 def show_env_changes(env_old, env_new):
     """Print out all test-specific env values."""
     print("--- os.environ changed values: ---")
-    all_keys = set(list(env_old.keys()) + list(env_new.keys()))
+    all_keys = env_old.keys() | env_new.keys()
     for k in sorted(all_keys):
         old_value = env_old.get(k, "")
         new_value = env_new.get(k, "")
         if new_value and old_value != new_value:
-            print('{}="{}"'.format(k, new_value))
+            print(f'{k}="{new_value}"')
     print("-" * 20)
 
 
@@ -173,13 +173,13 @@ def after_scenario(context, scenario):
         # Quit nicely.
         if not context.atprompt:
             dbname = context.currentdb
-            context.cli.expect_exact("{0}> ".format(dbname), timeout=15)
+            context.cli.expect_exact(f"{dbname}> ", timeout=15)
         context.cli.sendcontrol("c")
         context.cli.sendcontrol("d")
         try:
             context.cli.expect_exact(pexpect.EOF, timeout=15)
         except pexpect.TIMEOUT:
-            print("--- after_scenario {}: kill cli".format(scenario.name))
+            print(f"--- after_scenario {scenario.name}: kill cli")
             context.cli.kill(signal.SIGKILL)
     if hasattr(context, "tmpfile_sql_help") and context.tmpfile_sql_help:
         context.tmpfile_sql_help.close()
diff --git a/tests/features/fixture_utils.py b/tests/features/fixture_utils.py
index 16f123a6..70b603d8 100644
--- a/tests/features/fixture_utils.py
+++ b/tests/features/fixture_utils.py
@@ -18,7 +18,7 @@ def read_fixture_files():
     """Read all files inside fixture_data directory."""
     current_dir = os.path.dirname(__file__)
     fixture_dir = os.path.join(current_dir, "fixture_data/")
-    print("reading fixture data: {}".format(fixture_dir))
+    print(f"reading fixture data: {fixture_dir}")
     fixture_dict = {}
     for filename in os.listdir(fixture_dir):
         if filename not in [".", ".."]:
diff --git a/tests/features/steps/basic_commands.py b/tests/features/steps/basic_commands.py
index a1fca8b0..07e9ec17 100644
--- a/tests/features/steps/basic_commands.py
+++ b/tests/features/steps/basic_commands.py
@@ -66,19 +66,19 @@ def step_ctrl_d(context):
     """
     # turn off pager before exiting
     context.cli.sendcontrol("c")
-    context.cli.sendline("\pset pager off")
+    context.cli.sendline(r"\pset pager off")
     wrappers.wait_prompt(context)
     context.cli.sendcontrol("d")
     context.cli.expect(pexpect.EOF, timeout=15)
     context.exit_sent = True
 
 
-@when('we send "\?" command')
+@when(r'we send "\?" command')
 def step_send_help(context):
-    """
+    r"""
     Send \? to see help.
     """
-    context.cli.sendline("\?")
+    context.cli.sendline(r"\?")
 
 
 @when("we send partial select command")
@@ -97,9 +97,9 @@ def step_see_error_message(context):
 @when("we send source command")
 def step_send_source_command(context):
     context.tmpfile_sql_help = tempfile.NamedTemporaryFile(prefix="pgcli_")
-    context.tmpfile_sql_help.write(b"\?")
+    context.tmpfile_sql_help.write(br"\?")
     context.tmpfile_sql_help.flush()
-    context.cli.sendline("\i {0}".format(context.tmpfile_sql_help.name))
+    context.cli.sendline(fr"\i {context.tmpfile_sql_help.name}")
     wrappers.expect_exact(context, context.conf["pager_boundary"] + "\r\n", timeout=5)
 
 
diff --git a/tests/features/steps/crud_database.py b/tests/features/steps/crud_database.py
index 3fd8b7a1..3f5d0e71 100644
--- a/tests/features/steps/crud_database.py
+++ b/tests/features/steps/crud_database.py
@@ -14,7 +14,7 @@ def step_db_create(context):
     """
     Send create database.
     """
-    context.cli.sendline("create database {0};".format(context.conf["dbname_tmp"]))
+    context.cli.sendline("create database {};".format(context.conf["dbname_tmp"]))
 
     context.response = {"database_name": context.conf["dbname_tmp"]}
 
@@ -24,7 +24,7 @@ def step_db_drop(context):
     """
     Send drop database.
     """
-    context.cli.sendline("drop database {0};".format(context.conf["dbname_tmp"]))
+    context.cli.sendline("drop database {};".format(context.conf["dbname_tmp"]))
 
 
 @when("we connect to test database")
@@ -33,7 +33,7 @@ def step_db_connect_test(context):
     Send connect to database.
     """
     db_name = context.conf["dbname"]
-    context.cli.sendline("\\connect {0}".format(db_name))
+    context.cli.sendline(f"\\connect {db_name}")
 
 
 @when("we connect to dbserver")
@@ -59,7 +59,7 @@ def step_see_prompt(context):
     Wait to see the prompt.
     """
     db_name = getattr(context, "currentdb", context.conf["dbname"])
-    wrappers.expect_exact(context, "{0}> ".format(db_name), timeout=5)
+    wrappers.expect_exact(context, f"{db_name}> ", timeout=5)
     context.atprompt = True
 
 
diff --git a/tests/features/steps/expanded.py b/tests/features/steps/expanded.py
index f34fcf04..265ea39b 100644
--- a/tests/features/steps/expanded.py
+++ b/tests/features/steps/expanded.py
@@ -31,7 +31,7 @@ def step_prepare_data(context):
 @when("we set expanded {mode}")
 def step_set_expanded(context, mode):
     """Set expanded to mode."""
-    context.cli.sendline("\\" + "x {}".format(mode))
+    context.cli.sendline("\\" + f"x {mode}")
     wrappers.expect_exact(context, "Expanded display is", timeout=2)
     wrappers.wait_prompt(context)
 
diff --git a/tests/features/steps/iocommands.py b/tests/features/steps/iocommands.py
index 613aeb29..a614490a 100644
--- a/tests/features/steps/iocommands.py
+++ b/tests/features/steps/iocommands.py
@@ -13,7 +13,7 @@ def step_edit_file(context):
     )
     if os.path.exists(context.editor_file_name):
         os.remove(context.editor_file_name)
-    context.cli.sendline("\e {0}".format(os.path.basename(context.editor_file_name)))
+    context.cli.sendline(r"\e {}".format(os.path.basename(context.editor_file_name)))
     wrappers.expect_exact(
         context, 'Entering Ex mode.  Type "visual" to go to Normal mode.', timeout=2
     )
@@ -53,7 +53,7 @@ def step_tee_ouptut(context):
     )
     if os.path.exists(context.tee_file_name):
         os.remove(context.tee_file_name)
-    context.cli.sendline("\o {0}".format(os.path.basename(context.tee_file_name)))
+    context.cli.sendline(r"\o {}".format(os.path.basename(context.tee_file_name)))
     wrappers.expect_exact(context, context.conf["pager_boundary"] + "\r\n", timeout=5)
     wrappers.expect_exact(context, "Writing to file", timeout=5)
     wrappers.expect_exact(context, context.conf["pager_boundary"] + "\r\n", timeout=5)
@@ -67,7 +67,7 @@ def step_query_select_123456(context):
 
 @when("we stop teeing output")
 def step_notee_output(context):
-    context.cli.sendline("\o")
+    context.cli.sendline(r"\o")
     wrappers.expect_exact(context, "Time", timeout=5)
 
 
diff --git a/tests/features/steps/wrappers.py b/tests/features/steps/wrappers.py
index e0f5a20e..78d76881 100644
--- a/tests/features/steps/wrappers.py
+++ b/tests/features/steps/wrappers.py
@@ -57,7 +57,7 @@ def run_cli(context, run_args=None, prompt_check=True, currentdb=None):
     context.cli.logfile = context.logfile
     context.exit_sent = False
     context.currentdb = currentdb or context.conf["dbname"]
-    context.cli.sendline("\pset pager always")
+    context.cli.sendline(r"\pset pager always")
     if prompt_check:
         wait_prompt(context)
 
diff --git a/tests/metadata.py b/tests/metadata.py
index 2f89ea28..4ebcccd0 100644
--- a/tests/metadata.py
+++ b/tests/metadata.py
@@ -3,7 +3,7 @@ from itertools import product
 from pgcli.packages.parseutils.meta import FunctionMetadata, ForeignKey
 from prompt_toolkit.completion import Completion
 from prompt_toolkit.document import Document
-from mock import Mock
+from unittest.mock import Mock
 import pytest
 
 parametrize = pytest.mark.parametrize
@@ -59,7 +59,7 @@ def wildcard_expansion(cols, pos=-1):
     return Completion(cols, start_position=pos, display_meta="columns", display="*")
 
 
-class MetaData(object):
+class MetaData:
     def __init__(self, metadata):
         self.metadata = metadata
 
@@ -128,7 +128,7 @@ class MetaData(object):
         ]
 
     def schemas(self, pos=0):
-        schemas = set(sch for schs in self.metadata.values() for sch in schs)
+        schemas = {sch for schs in self.metadata.values() for sch in schs}
         return [schema(escape(s), pos=pos) for s in schemas]
 
     def functions_and_keywords(self, parent="public", pos=0):
diff --git a/tests/parseutils/test_parseutils.py b/tests/parseutils/test_pars