Revert "Revert fix to ensure tests catches the issue"

This reverts commit 39e2f87.

Author: ishymko

src/a2a/client/transports/http_helpers.py

@@ -6,7 +6,7 @@
 
 import httpx
 
-from httpx_sse import EventSource, SSEError, aconnect_sse
+from httpx_sse import EventSource, SSEError
 
 from a2a.client.client import ClientCallContext
 from a2a.client.errors import A2AClientError, A2AClientTimeoutError
@@ -75,7 +75,7 @@ async def send_http_stream_request(
 ) -> AsyncGenerator[str]:
     """Sends a streaming HTTP request, yielding SSE data strings and handling exceptions."""
     with handle_http_exceptions(status_error_handler):
-        async with aconnect_sse(
+        async with _SSEEventSource(
             httpx_client, method, url, **kwargs
         ) as event_source:
             try:

tests/client/transports/test_jsonrpc_client.py

@@ -433,7 +433,7 @@ async def test_close(self, transport, mock_httpx_client):
 
 class TestStreamingErrors:
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_sse_error(
         self,
         mock_aconnect_sse: AsyncMock,
@@ -457,7 +457,7 @@ async def test_send_message_streaming_sse_error(
                 pass
 
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_request_error(
         self,
         mock_aconnect_sse: AsyncMock,
@@ -483,7 +483,7 @@ async def test_send_message_streaming_request_error(
                 pass
 
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_timeout(
         self,
         mock_aconnect_sse: AsyncMock,
@@ -560,7 +560,7 @@ async def test_extensions_added_to_request(
         )
 
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_server_error_propagates(
         self,
         mock_aconnect_sse: AsyncMock,

tests/client/transports/test_rest_client.py

@@ -70,7 +70,7 @@ def _assert_extensions_header(mock_kwargs: dict, expected_extensions: set[str]):
 
 class TestRestTransport:
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_timeout(
         self,
         mock_aconnect_sse: AsyncMock,
@@ -280,7 +280,7 @@ async def test_send_message_with_default_extensions(
         )
 
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_with_new_extensions(
         self,
         mock_aconnect_sse: AsyncMock,
@@ -329,7 +329,7 @@ async def test_send_message_streaming_with_new_extensions(
         )
 
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_send_message_streaming_server_error_propagates(
         self,
         mock_aconnect_sse: AsyncMock,
@@ -693,7 +693,7 @@ async def test_rest_get_task_prepend_empty_tenant(
         ],
     )
     @pytest.mark.asyncio
-    @patch('a2a.client.transports.http_helpers.aconnect_sse')
+    @patch('a2a.client.transports.http_helpers._SSEEventSource')
     async def test_rest_streaming_methods_prepend_tenant(  # noqa: PLR0913
         self,
         mock_aconnect_sse,