chore: import upstream snapshot with attribution

test/components/joiners/test_string_joiner.py

@@ -0,0 +1,37 @@
+# SPDX-FileCopyrightText: 2022-present deepset GmbH <info@deepset.ai>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from haystack.components.joiners.string_joiner import StringJoiner
+from haystack.core.serialization import component_from_dict, component_to_dict
+
+
+class TestStringJoiner:
+    def test_init(self):
+        joiner = StringJoiner()
+        assert isinstance(joiner, StringJoiner)
+
+    def test_to_dict(self):
+        joiner = StringJoiner()
+        data = component_to_dict(joiner, name="string_joiner")
+        assert data == {"type": "haystack.components.joiners.string_joiner.StringJoiner", "init_parameters": {}}
+
+    def test_from_dict(self):
+        data = {"type": "haystack.components.joiners.string_joiner.StringJoiner", "init_parameters": {}}
+        string_joiner = component_from_dict(StringJoiner, data=data, name="string_joiner")
+        assert isinstance(string_joiner, StringJoiner)
+
+    def test_empty_list(self):
+        joiner = StringJoiner()
+        result = joiner.run([])
+        assert result == {"strings": []}
+
+    def test_single_string(self):
+        joiner = StringJoiner()
+        result = joiner.run("a")
+        assert result == {"strings": ["a"]}
+
+    def test_two_strings(self):
+        joiner = StringJoiner()
+        result = joiner.run(["a", "b"])
+        assert result == {"strings": ["a", "b"]}