(fix) get_response_headers for Azure OpenAI (#6344)

* fix get_response_headers

* unit testing for get headers

* unit testing for anthropic / azure openai headers

* increase test coverage for test_completion_response_ratelimit_headers

* fix test rate limit headers

tests/llm_translation/test_llm_response_utils/test_get_headers.py

@@ -0,0 +1,79 @@
+import json
+import os
+import sys
+from datetime import datetime
+
+sys.path.insert(
+    0, os.path.abspath("../../")
+)  # Adds the parent directory to the system path
+
+import litellm
+import pytest
+
+from litellm.litellm_core_utils.llm_response_utils.get_headers import (
+    get_response_headers,
+    _get_llm_provider_headers,
+)
+
+
+def test_get_response_headers_empty():
+    result = get_response_headers()
+    assert result == {}, "Expected empty dictionary for no input"
+
+
+def test_get_response_headers_with_openai_headers():
+    """
+    OpenAI headers are forwarded as is
+    Other headers are prefixed with llm_provider-
+    """
+    input_headers = {
+        "x-ratelimit-limit-requests": "100",
+        "x-ratelimit-remaining-requests": "50",
+        "x-ratelimit-limit-tokens": "1000",
+        "x-ratelimit-remaining-tokens": "500",
+        "other-header": "value",
+    }
+    expected_output = {
+        "x-ratelimit-limit-requests": "100",
+        "x-ratelimit-remaining-requests": "50",
+        "x-ratelimit-limit-tokens": "1000",
+        "x-ratelimit-remaining-tokens": "500",
+        "llm_provider-x-ratelimit-limit-requests": "100",
+        "llm_provider-x-ratelimit-remaining-requests": "50",
+        "llm_provider-x-ratelimit-limit-tokens": "1000",
+        "llm_provider-x-ratelimit-remaining-tokens": "500",
+        "llm_provider-other-header": "value",
+    }
+    result = get_response_headers(input_headers)
+    assert result == expected_output, "Unexpected output for OpenAI headers"
+
+
+def test_get_response_headers_without_openai_headers():
+    """
+    Non-OpenAI headers are prefixed with llm_provider-
+    """
+    input_headers = {"custom-header-1": "value1", "custom-header-2": "value2"}
+    expected_output = {
+        "llm_provider-custom-header-1": "value1",
+        "llm_provider-custom-header-2": "value2",
+    }
+    result = get_response_headers(input_headers)
+    assert result == expected_output, "Unexpected output for non-OpenAI headers"
+
+
+def test_get_llm_provider_headers():
+    """
+    If non OpenAI headers are already prefixed with llm_provider- they are not prefixed with llm_provider- again
+    """
+    input_headers = {
+        "header1": "value1",
+        "header2": "value2",
+        "llm_provider-existing": "existing_value",
+    }
+    expected_output = {
+        "llm_provider-header1": "value1",
+        "llm_provider-header2": "value2",
+        "llm_provider-existing": "existing_value",
+    }
+    result = _get_llm_provider_headers(input_headers)
+    assert result == expected_output, "Unexpected output for _get_llm_provider_headers"