Merge surrogate pairs in Windows VT100 console input

src/prompt_toolkit/input/win32.py

@@ -639,7 +639,13 @@ def read(self) -> Iterable[KeyPress]:
 
         # First, get all the keys from the input buffer, in order to determine
         # whether we should consider this a paste event or not.
-        for key_data in self._get_keys(read, input_records):
+        # Non-BMP characters are passed as separate surrogate codes; combine
+        # paired surrogates into a single character.
+        data = "".join(self._get_keys(read, input_records))
+        data = data.encode("utf-16-le", "surrogatepass").decode(
+            "utf-16-le", "surrogatepass"
+        )
+        for key_data in data:
             self._vt100_parser.feed(key_data)
 
         # Return result.

tests/test_win32_input.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+import sys
+
+import pytest
+
+pytestmark = pytest.mark.skipif(sys.platform != "win32", reason="Windows only")
+
+
+def test_vt100_console_input_reader_combines_surrogate_pairs(monkeypatch):
+    from prompt_toolkit.input import win32
+
+    # U+1F132 is sent by the console as two key events: a high and a low
+    # UTF-16 surrogate.
+    units = ["a", "\ud83c", "\udd32", "b"]
+
+    class FakeKernel32:
+        def GetStdHandle(self, handle):
+            return 0
+
+        def ReadConsoleInputW(self, handle, records, max_count, read):
+            for i, unit in enumerate(units):
+                record = records.contents[i]
+                record.EventType = 1  # KEY_EVENT
+                record.Event.KeyEvent.KeyDown = 1
+                record.Event.KeyEvent.uChar.UnicodeChar = unit
+            read.contents.value = len(units)
+
+    class FakeWindll:
+        kernel32 = FakeKernel32()
+
+    class FakeStdin:
+        def isatty(self):
+            return True
+
+    monkeypatch.setattr(win32, "windll", FakeWindll())
+    monkeypatch.setattr(win32, "wait_for_handles", lambda handles, timeout: True)
+    monkeypatch.setattr(sys, "stdin", FakeStdin())
+
+    reader = win32.Vt100ConsoleInputReader()
+    keys = list(reader.read()) + reader.flush_keys()
+
+    assert [key.key for key in keys] == ["a", "\U0001f132", "b"]