test obfuscate_sensitive_headers via public api (#3063)

Author: T-256

tests/test_utils.py

@@ -12,7 +12,6 @@
     get_ca_bundle_from_env,
     get_environment_proxies,
     is_https_redirect,
-    obfuscate_sensitive_headers,
     parse_header_links,
     same_origin,
 )
@@ -215,10 +214,9 @@ def test_get_environment_proxies(environment, proxies):
     ],
 )
 def test_obfuscate_sensitive_headers(headers, output):
-    bytes_headers = [(k.encode(), v.encode()) for k, v in headers]
-    bytes_output = [(k.encode(), v.encode()) for k, v in output]
-    assert list(obfuscate_sensitive_headers(headers)) == output
-    assert list(obfuscate_sensitive_headers(bytes_headers)) == bytes_output
+    as_dict = {k: v for k, v in output}
+    headers_class = httpx.Headers({k: v for k, v in headers})
+    assert repr(headers_class) == f"Headers({as_dict!r})"
 
 
 def test_same_origin():