diff --git a/tests/unit/llms/anthropic/test_anthropic_common_utils.py b/tests/unit/llms/anthropic/test_anthropic_common_utils.py
index aa0aebaa9c9..3feb730b2e1 100644
--- a/tests/unit/llms/anthropic/test_anthropic_common_utils.py
+++ b/tests/unit/llms/anthropic/test_anthropic_common_utils.py
@@ -4692,6 +4692,18 @@ def test_requires_native_compaction_beta_is_false_without_a_signal(
     assert requires_native_compaction_beta(provider, optional_params, messages) is False
 
 
+def test_merge_header_sources_keeps_only_the_string_betas_of_a_mixed_list() -> None:
+    merged: Final = merge_header_sources(
+        {"anthropic-beta": ["context-1m-2025-08-07", b"bytes-beta", ("nested",), object(), 3]},
+        {"Anthropic-Beta": "message-threads-2026-08-12", "x-other": "kept"},
+    )
+
+    assert dict(merged) == {
+        "anthropic-beta": "context-1m-2025-08-07,message-threads-2026-08-12",
+        "x-other": "kept",
+    }
+
+
 @pytest.mark.parametrize(
     ("custom_llm_provider", "model", "expected"),
     [
@@ -4733,15 +4745,3 @@ def test_tools_without_strict_drops_only_the_strict_key_and_counts_the_strict_to
     assert tools_without_strict(tools) == ToolsWithoutStrict(
         tools=({"name": "a"}, {"name": "b"}, {"name": "c"}), dropped_count=1
     )
-
-
-def test_merge_header_sources_keeps_only_the_string_betas_of_a_mixed_list() -> None:
-    merged: Final = merge_header_sources(
-        {"anthropic-beta": ["context-1m-2025-08-07", b"bytes-beta", ("nested",), object(), 3]},
-        {"Anthropic-Beta": "message-threads-2026-08-12", "x-other": "kept"},
-    )
-
-    assert dict(merged) == {
-        "anthropic-beta": "context-1m-2025-08-07,message-threads-2026-08-12",
-        "x-other": "kept",
-    }