diff --git a/b2sdk/_internal/testing/fixtures/account_info.py b/b2sdk/_internal/testing/fixtures/account_info.py
new file mode 100644
index 00000000..901d28a5
--- /dev/null
+++ b/b2sdk/_internal/testing/fixtures/account_info.py
@@ -0,0 +1,34 @@
+######################################################################
+#
+# File: b2sdk/_internal/testing/fixtures/account_info.py
+#
+# Copyright 2025 Backblaze Inc. All Rights Reserved.
+#
+# License https://www.backblaze.com/using_b2_code.html
+#
+######################################################################
+
+import pytest
+
+from b2sdk._internal.account_info.sqlite_account_info import (
+    B2_ACCOUNT_INFO_ENV_VAR,
+    XDG_CONFIG_HOME_ENV_VAR,
+)
+
+
+@pytest.fixture(scope='session')
+def change_account_info_dir(monkeysession, tmp_path_factory):
+    """
+    For the entire test session:
+    1) temporarily remove B2_APPLICATION_KEY and B2_APPLICATION_KEY_ID from the environment
+    2) create a temporary directory for storing account info database
+    3) set B2_ACCOUNT_INFO_ENV_VAR to point to the temporary account info file
+    """
+
+    monkeysession.delenv('B2_APPLICATION_KEY_ID', raising=False)
+    monkeysession.delenv('B2_APPLICATION_KEY', raising=False)
+
+    temp_dir = tmp_path_factory.mktemp('b2_config')
+
+    monkeysession.setenv(B2_ACCOUNT_INFO_ENV_VAR, str(temp_dir / ('.b2_account_info')))
+    monkeysession.setenv(XDG_CONFIG_HOME_ENV_VAR, str(temp_dir))
diff --git a/b2sdk/_internal/testing/fixtures/common.py b/b2sdk/_internal/testing/fixtures/common.py
new file mode 100644
index 00000000..041f482a
--- /dev/null
+++ b/b2sdk/_internal/testing/fixtures/common.py
@@ -0,0 +1,16 @@
+######################################################################
+#
+# File: b2sdk/_internal/testing/fixtures/common.py
+#
+# Copyright 2025 Backblaze Inc. All Rights Reserved.
+#
+# License https://www.backblaze.com/using_b2_code.html
+#
+######################################################################
+import pytest
+
+
+@pytest.fixture(scope='session')
+def monkeysession():
+    with pytest.MonkeyPatch.context() as mp:
+        yield mp
diff --git a/b2sdk/v3/testing/__init__.py b/b2sdk/v3/testing/__init__.py
index 2cdbd76e..bd2d012b 100644
--- a/b2sdk/v3/testing/__init__.py
+++ b/b2sdk/v3/testing/__init__.py
@@ -45,3 +45,5 @@
     bucket,
     b2_subfolder,
 )
+from b2sdk._internal.testing.fixtures.common import monkeysession
+from b2sdk._internal.testing.fixtures.account_info import change_account_info_dir
diff --git a/changelog.d/+account_info_change_dir.infrastructure.md b/changelog.d/+account_info_change_dir.infrastructure.md
new file mode 100644
index 00000000..5be2b9ef
--- /dev/null
+++ b/changelog.d/+account_info_change_dir.infrastructure.md
@@ -0,0 +1 @@
+Set temporary directory as account info config dir in tests.
diff --git a/test/integration/conftest.py b/test/integration/conftest.py
new file mode 100644
index 00000000..d700e2fd
--- /dev/null
+++ b/test/integration/conftest.py
@@ -0,0 +1,15 @@
+######################################################################
+#
+# File: test/integration/conftest.py
+#
+# Copyright 2025 Backblaze Inc. All Rights Reserved.
+#
+# License https://www.backblaze.com/using_b2_code.html
+#
+######################################################################
+import pytest
+
+
+@pytest.fixture(scope='session', autouse=True)
+def auto_change_account_info_dir(change_account_info_dir):
+    pass
diff --git a/test/unit/account_info/test_account_info.py b/test/unit/account_info/test_account_info.py
index 65069d8f..cfa43e8f 100644
--- a/test/unit/account_info/test_account_info.py
+++ b/test/unit/account_info/test_account_info.py
@@ -485,10 +485,6 @@ def test_account_info_env_var_overrides_xdg_config_home(self):
             actual_path = os.path.abspath(account_info.filename)
             assert expected_path == actual_path
 
-    def test_resolve_xdg_os_default(self):
-        is_xdg_os = bool(SqliteAccountInfo._get_xdg_config_path())
-        assert is_xdg_os == (sys.platform not in ('win32', 'darwin'))
-
     def test_resolve_xdg_os_default_no_env_var(self, monkeypatch):
         # ensure that XDG_CONFIG_HOME_ENV_VAR doesn't to resolve XDG-like OS
         monkeypatch.delenv(XDG_CONFIG_HOME_ENV_VAR, raising=False)
diff --git a/test/unit/conftest.py b/test/unit/conftest.py
index cbf31e35..8d208fb0 100644
--- a/test/unit/conftest.py
+++ b/test/unit/conftest.py
@@ -149,6 +149,11 @@ def test_function(self):
                 pytest.skip('test requires apiver to be in range: [%d, %d]' % (from_ver, to_ver))
 
 
+@pytest.fixture(scope='session', autouse=True)
+def auto_change_account_info_dir(change_account_info_dir):
+    pass
+
+
 @pytest.fixture(scope='session')
 def apiver(request):
     """Get apiver as a v-prefixed string, e.g. "v2"."""