test: 添加 Gemini 流式解析和格式转换相关测试

- 添加 Gemini JSON-array 兜底解析测试
- 添加 Gemini stream_parser 单元测试
- 添加 provider transport URL 构建测试

tests/api/handlers/gemini/test_stream_parser.py

@@ -0,0 +1,20 @@
+from src.api.handlers.gemini.stream_parser import GeminiStreamParser
+
+
+def test_is_done_event_true_for_new_finish_reason_values() -> None:
+    parser = GeminiStreamParser()
+    event = {"candidates": [{"finishReason": "MALFORMED_FUNCTION_CALL"}]}
+    assert parser.is_done_event(event) is True
+
+
+def test_is_done_event_false_for_unspecified() -> None:
+    parser = GeminiStreamParser()
+    event = {"candidates": [{"finishReason": "FINISH_REASON_UNSPECIFIED"}]}
+    assert parser.is_done_event(event) is False
+
+
+def test_is_done_event_false_when_no_candidates_or_reason() -> None:
+    parser = GeminiStreamParser()
+    assert parser.is_done_event({}) is False
+    assert parser.is_done_event({"candidates": [{}]}) is False
+