Strip default headers from recorded files case-insensitively

CHANGES

@@ -6,6 +6,10 @@
   `content_type` is now used.
 * Added strict_match to urlencoded_params_matcher, enabling partial request parameter
   matching.
+* Default headers (such as ``Content-Type``, ``Date`` and ``Server``) are now stripped
+  from recorded files regardless of header name case. Previously, responses recorded from
+  servers that send lowercase header names (for example over HTTP/2) kept these redundant
+  headers in the generated file.
 
 0.26.0
 ------

responses/_recorder.py

@@ -52,11 +52,15 @@ def _remove_default_headers(data: "Any") -> "Any":
             "Connection",
             "Content-Encoding",
         ]
+        # HTTP header names are case-insensitive, and HTTP/2 servers send them
+        # lowercase, so match without regard to case.
+        keys_to_remove_lower = {key.lower() for key in keys_to_remove}
         for i, response in enumerate(data["responses"]):
-            for key in keys_to_remove:
-                if key in response["response"]["headers"]:
-                    del data["responses"][i]["response"]["headers"][key]
-            if not response["response"]["headers"]:
+            headers = data["responses"][i]["response"]["headers"]
+            for key in list(headers):
+                if key.lower() in keys_to_remove_lower:
+                    del headers[key]
+            if not headers:
                 del data["responses"][i]["response"]["headers"]
     return data
 

responses/tests/test_recorder.py

@@ -8,6 +8,7 @@
 import responses
 from responses import _recorder
 from responses._recorder import _dump
+from responses._recorder import _remove_default_headers
 
 try:
     import tomli as _toml
@@ -67,6 +68,44 @@ def get_data(host, port):
     return data
 
 
+def test_remove_default_headers_is_case_insensitive():
+    """Default headers should be stripped regardless of their case.
+
+    HTTP/2 servers send header names in lowercase, so the recorded file may
+    contain e.g. ``content-type`` / ``date`` rather than ``Content-Type`` /
+    ``Date``. These still need to be removed, otherwise the recorded file
+    keeps verbose default headers (and, for content-type, a value that is
+    already stored in the ``content_type`` field).
+    """
+    data = {
+        "responses": [
+            {
+                "response": {
+                    # mixed lower/title/upper case to pin the case-insensitive contract
+                    "headers": {
+                        "content-type": "application/json",
+                        "Date": "Mon, 01 Jan 2024 00:00:00 GMT",
+                        "SERVER": "nginx",
+                        "x-custom": "keep-me",
+                    }
+                }
+            },
+            {
+                # a response whose headers are all default ones is left without a
+                # "headers" key at all
+                "response": {
+                    "headers": {"content-length": "12", "connection": "keep-alive"}
+                }
+            },
+        ]
+    }
+
+    result = _remove_default_headers(data)
+
+    assert result["responses"][0]["response"]["headers"] == {"x-custom": "keep-me"}
+    assert "headers" not in result["responses"][1]["response"]
+
+
 class TestRecord:
     def setup_method(self):
         self.out_file = Path("response_record")