Nc/combining output parser (#3014)

Co-authored-by: vowelparrot <130414180+vowelparrot@users.noreply.github.com>

tests/unit_tests/output_parsers/test_combining_parser.py

@@ -0,0 +1,45 @@
+"""Test in memory docstore."""
+from langchain.output_parsers.combining import CombiningOutputParser
+from langchain.output_parsers.regex import RegexParser
+from langchain.output_parsers.structured import ResponseSchema, StructuredOutputParser
+
+DEF_EXPECTED_RESULT = {
+    "answer": "Paris",
+    "source": "https://en.wikipedia.org/wiki/France",
+    "confidence": "A",
+    "explanation": "Paris is the capital of France according to Wikipedia.",
+}
+
+DEF_README = """```json
+{
+    "answer": "Paris",
+    "source": "https://en.wikipedia.org/wiki/France"
+}
+```
+
+//Confidence: A, Explanation: Paris is the capital of France according to Wikipedia."""
+
+
+def test_combining_dict_result() -> None:
+    """Test combining result."""
+    parsers = [
+        StructuredOutputParser(
+            response_schemas=[
+                ResponseSchema(
+                    name="answer", description="answer to the user's question"
+                ),
+                ResponseSchema(
+                    name="source",
+                    description="source used to answer the user's question",
+                ),
+            ]
+        ),
+        RegexParser(
+            regex=r"Confidence: (A|B|C), Explanation: (.*)",
+            output_keys=["confidence", "explanation"],
+            default_output_key="noConfidence",
+        ),
+    ]
+    combining_parser = CombiningOutputParser(parsers=parsers)
+    result_dict = combining_parser.parse(DEF_README)
+    assert DEF_EXPECTED_RESULT == result_dict