Use supported_features=['debugger'] in kernel info reply

ipykernel/kernelbase.py

@@ -891,6 +891,12 @@ def kernel_info(self):
         }
         if self._supports_kernel_subshells:
             info["supported_features"] = ["kernel subshells"]
+
+        from .debugger import _is_debugpy_available
+
+        if _is_debugpy_available:
+            info["supported_features"].append("debugger")
+
         return info
 
     async def kernel_info_request(self, socket, ident, parent):

tests/test_debugger.py

@@ -96,6 +96,17 @@ def test_debug_initialize(kernel):
         assert reply == {}
 
 
+def test_supported_features(kernel_with_debug):
+    kernel_with_debug.kernel_info()
+    reply = kernel_with_debug.get_shell_msg(timeout=TIMEOUT)
+    supported_features = reply["content"]["supported_features"]
+
+    if debugpy:
+        assert "debugger" in supported_features
+    else:
+        assert "debugger" not in supported_features
+
+
 def test_attach_debug(kernel_with_debug):
     reply = wait_for_debug_request(
         kernel_with_debug, "evaluate", {"expression": "'a' + 'b'", "context": "repl"}