diff --git a/tests/unit/secrets/test_secrets_handler.py b/tests/unit/secrets/test_secrets_handler.py
new file mode 100644
index 0000000..4d39fed
--- /dev/null
+++ b/tests/unit/secrets/test_secrets_handler.py
@@ -0,0 +1,149 @@
+# Copyright 2021 - 2024 Universität Tübingen, DKFZ, EMBL, and Universität zu Köln
+# for the German Human Genome-Phenome Archive (GHGA)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unit tests for the SecretsHandler class"""
+
+from unittest.mock import Mock, call
+
+import pytest
+from hvac.exceptions import InvalidPath
+
+from sms.core.secrets_handler import SecretsHandler
+from tests.fixtures.config import DEFAULT_TEST_CONFIG
+
+
+@pytest.mark.parametrize(
+    "secrets",
+    [[], ["key1"], ["key1", "key2"]],
+    ids=["empty", "single", "multiple"],
+)
+def test_get_secrets(monkeypatch: pytest.MonkeyPatch, secrets: list[str]):
+    """Test get_secrets method without errors"""
+    # patch the hvac client with a mock
+    mock_client = Mock()
+    mock_client.secrets.kv.v2.list_secrets.return_value = {"data": {"keys": secrets}}
+    monkeypatch.setattr(SecretsHandler, "client", mock_client)
+    secrets_handler = SecretsHandler(config=DEFAULT_TEST_CONFIG)
+
+    assert secrets_handler.get_secrets() == secrets
+    mock_client.secrets.kv.v2.list_secrets.assert_called_once()
+
+
+def test_get_secrets_error(monkeypatch: pytest.MonkeyPatch, caplog):
+    """Test get_secrets method with an error"""
+    # patch the hvac client with a mock
+    mock_client = Mock()
+    mock_client.secrets.kv.v2.list_secrets.side_effect = InvalidPath("Invalid path")
+    monkeypatch.setattr(SecretsHandler, "client", mock_client)
+    secrets_handler = SecretsHandler(config=DEFAULT_TEST_CONFIG)
+
+    # Make sure the error is logged as a warning but an empty list is still returned
+    caplog.clear()
+    secrets = secrets_handler.get_secrets()
+    assert len(caplog.messages) == 1
+    assert caplog.messages[0] == (
+        "Invalid path error when fetching secrets. The path might be invalid,"
+        + " or no secrets may exist."
+    )
+    assert caplog.records[0].levelname == "WARNING"
+    assert secrets == []
+    mock_client.secrets.kv.v2.list_secrets.assert_called_once()
+
+
+def test_delete_secrets_error(monkeypatch: pytest.MonkeyPatch):
+    """Test delete_secrets method on empty vault and without specifying secrets."""
+    # patch the hvac client with a mock
+    mock_client = Mock()
+    mock_client.secrets.kv.v2.list_secrets.side_effect = InvalidPath("Invalid path")
+    monkeypatch.setattr(SecretsHandler, "client", mock_client)
+    secrets_handler = SecretsHandler(config=DEFAULT_TEST_CONFIG)
+
+    # Call delete_secrets() without specifying secrets in order to trigger get_secrets
+    secrets_handler.delete_secrets()
+    mock_client.secrets.kv.v2.list_secrets.assert_called_once()
+    mock_client.secrets.kv.v2.delete_metadata_and_all_versions.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "secrets_to_delete",
+    [
+        None,
+        [],
+        ["key1"],
+        ["key2"],
+        ["key1", "key2"],
+    ],
+    ids=[
+        "None",
+        "Empty",
+        "DeleteKey1",
+        "DeleteKey2",
+        "DeleteBoth",
+    ],
+)
+@pytest.mark.parametrize(
+    "stored_secrets",
+    [[], ["key1"], ["key1", "key2"]],
+    ids=["Empty", "OneSecret", "TwoSecrets"],
+)
+def test_delete_successful(
+    monkeypatch: pytest.MonkeyPatch,
+    secrets_to_delete: list[str] | None,
+    stored_secrets: list[str],
+):
+    """Test delete_secrets method.
+
+    Use a variety of combinations of stored secrets and secrets to delete.
+    """
+    # create a mock for the hvac client
+    list_stored_secrets = {"data": {"keys": stored_secrets}}
+    mock_client = Mock()
+
+    # list_secrets either returns all keys or raises an InvalidPath error
+    if stored_secrets:
+        mock_client.secrets.kv.v2.list_secrets.return_value = list_stored_secrets
+    else:
+        mock_client.secrets.kv.v2.list_secrets.side_effect = InvalidPath("Invalid path")
+
+    # apply the mock to the SecretsHandler
+    monkeypatch.setattr(SecretsHandler, "client", mock_client)
+    secrets_handler = SecretsHandler(config=DEFAULT_TEST_CONFIG)
+
+    # call delete_secrets()
+    secrets_handler.delete_secrets(secrets=secrets_to_delete)
+
+    # list_secrets is ONLY called if secrets_to_delete is None or empty list
+    if not secrets_to_delete:
+        mock_client.secrets.kv.v2.list_secrets.assert_called_once()
+    else:
+        mock_client.secrets.kv.v2.list_secrets.assert_not_called()
+
+    # delete_metadata_and_all_versions is called for each secret in secrets_to_delete
+    #   if that's not supplied, then it is called for each value in list_secrets
+    calls = (
+        [
+            call(path=f"{DEFAULT_TEST_CONFIG.vault_path}/{secret}")
+            for secret in stored_secrets
+        ]
+        if not secrets_to_delete
+        else [
+            call(path=f"{DEFAULT_TEST_CONFIG.vault_path}/{secret}")
+            for secret in secrets_to_delete
+        ]
+    )
+    mock_client.secrets.kv.v2.delete_metadata_and_all_versions.assert_has_calls(
+        calls,
+        any_order=True,
+    )