[issue-487] add tests for the document_utils.py module

tests/spdx/test_document_utils.py

@@ -0,0 +1,28 @@
+#  SPDX-FileCopyrightText: 2023 spdx contributors
+#
+#  SPDX-License-Identifier: Apache-2.0
+from unittest import TestCase
+
+import pytest
+
+from spdx.document_utils import get_element_from_spdx_id, get_contained_spdx_element_ids
+from tests.spdx.fixtures import document_fixture, snippet_fixture, package_fixture, file_fixture
+
+
+@pytest.fixture
+def variables():
+    return document_fixture(), package_fixture(), file_fixture(), snippet_fixture()
+
+
+def test_contained_element_ids(variables):
+    document, package, file, snippet = variables
+    element_ids = get_contained_spdx_element_ids(document)
+    TestCase().assertCountEqual(element_ids, [package.spdx_id, file.spdx_id, snippet.spdx_id])
+
+
+def test_get_element_from_spdx_id(variables):
+    document, package, file, snippet = variables
+    assert get_element_from_spdx_id(document, package.spdx_id) == package
+    assert get_element_from_spdx_id(document, file.spdx_id) == file
+    assert get_element_from_spdx_id(document, snippet.spdx_id) == snippet
+    assert get_element_from_spdx_id(document, "unknown_id") is None