fix: Escaping header values in VCR cassettes

Ref: #783

docs/changelog.rst

@@ -15,10 +15,11 @@ Changelog
 
 **Fixed**
 
-- Fix ``User-Agent`` header overriding the passed one. `#757`_
+- ``User-Agent`` header overriding the passed one. `#757`_
 - Default ``User-Agent`` header in ``Case.call``. `#717`_
 - Status of individual interactions in VCR cassettes. Before this change, all statuses were taken from the overall test outcome,
   rather than from the check results for a particular response. `#695`_
+- Escaping header values in VCR cassettes. `#783`_
 
 **Changed**
 
@@ -1378,6 +1379,7 @@ Deprecated
 .. _0.3.0: https://github.com/schemathesis/schemathesis/compare/v0.2.0...v0.3.0
 .. _0.2.0: https://github.com/schemathesis/schemathesis/compare/v0.1.0...v0.2.0
 
+.. _#783: https://github.com/schemathesis/schemathesis/issues/783
 .. _#768: https://github.com/schemathesis/schemathesis/issues/768
 .. _#757: https://github.com/schemathesis/schemathesis/issues/757
 .. _#748: https://github.com/schemathesis/schemathesis/issues/748

src/schemathesis/cli/cassettes.py

@@ -1,4 +1,5 @@
 import base64
+import json
 import re
 import sys
 import threading
@@ -103,7 +104,7 @@ def worker(file_handle: click.utils.LazyFile, queue: Queue) -> None:
     stream = file_handle.open()
 
     def format_header_values(values: List[str]) -> str:
-        return "\n".join(f"      - '{v}'" for v in values)
+        return "\n".join(f"      - {json.dumps(v)}" for v in values)
 
     def format_headers(headers: Dict[str, List[str]]) -> str:
         return "\n".join(f"      {name}:\n{format_header_values(values)}" for name, values in headers.items())

test/cli/test_cassettes.py

@@ -188,6 +188,26 @@ async def test_replay(openapi_version, cli, schema_url, app, reset_app, cassette
         compare_headers(request, serialized["headers"])
 
 
+@pytest.mark.endpoints("headers")
+async def test_headers_serialization(cli, openapi2_schema_url, cassette_path):
+    # See GH-783
+    # When headers contain control characters that are not directly representable in YAML
+    result = cli.run(
+        openapi2_schema_url,
+        f"--store-network-log={cassette_path}",
+        "--hypothesis-max-examples=100",
+        "--hypothesis-seed=1",
+        "--validate-schema=false",
+    )
+    # Then tests should pass
+    assert result.exit_code == ExitCode.OK, result.stdout
+    # And cassette can be replayed
+    result = cli.replay(str(cassette_path))
+    assert result.exit_code == ExitCode.OK, result.stdout
+    # And should be loadable
+    load_cassette(cassette_path)
+
+
 def test_multiple_cookies(base_url):
     headers = {"User-Agent": USER_AGENT}
     response = requests.get(f"{base_url}/success", cookies={"foo": "bar", "baz": "spam"}, headers=headers)

test/conftest.py

@@ -109,6 +109,12 @@ def schema_url(server, app):
     return f"http://127.0.0.1:{server['port']}/schema.yaml"
 
 
+@pytest.fixture()
+def openapi2_schema_url(server, openapi_2_app):
+    """URL of the schema of the running application."""
+    return f"http://127.0.0.1:{server['port']}/schema.yaml"
+
+
 @pytest.fixture()
 def openapi3_schema_url(server, openapi_3_app):
     """URL of the schema of the running application."""