diff --git a/tests/resources/sut-json-load.py b/tests/resources/sut-json-load.py
index 999110e..8ebeed0 100755
--- a/tests/resources/sut-json-load.py
+++ b/tests/resources/sut-json-load.py
@@ -4,7 +4,7 @@
 import sys
 
 
-with open(sys.argv[1], 'r') as f:
+with open(sys.argv[1], 'r', encoding='utf-8') as f:
     j = json.load(f)
 
-print(repr(j))
+print(f'{j!r}')
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 6f71d1b..c73d46b 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2016-2022 Renata Hodovan, Akos Kiss.
+# Copyright (c) 2016-2023 Renata Hodovan, Akos Kiss.
 #
 # Licensed under the BSD 3-Clause License
 # <LICENSE.rst or https://opensource.org/licenses/BSD-3-Clause>.
@@ -6,10 +6,11 @@
 # according to those terms.
 
 import os
-import pytest
 import subprocess
 import sys
 
+import pytest
+
 
 is_windows = sys.platform.startswith('win32')
 script_ext = '.bat' if is_windows else '.sh'
@@ -40,8 +41,8 @@
 def test_cli(test, inp, exp, grammar, rule, input_format, args, tmpdir):
     out_dir = str(tmpdir)
     cmd = (sys.executable, '-m', 'picireny') \
-          + (f'--test={test}{script_ext}', f'--input={inp}', f'--out={out_dir}') \
-          + ('--log-level=TRACE', )
+        + (f'--test={test}{script_ext}', f'--input={inp}', f'--out={out_dir}') \
+        + ('--log-level=TRACE', )
     if grammar:
         cmd += (f'--grammar={grammar}', )
     if rule:
diff --git a/tox.ini b/tox.ini
index dbe62e8..e80cbfd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,9 +20,10 @@ omit = **/parser/*
 deps =
     pycodestyle
     pylint
+    pytest
 commands =
-    pylint picireny
-    pycodestyle picireny --ignore=E501 --exclude=picireny/antlr4/parser/ANTLRv4*.py
+    pylint picireny tests
+    pycodestyle picireny tests --ignore=E501 --exclude=picireny/antlr4/parser/ANTLRv4*.py
 
 [testenv:build]
 deps =