gh-121499: Fix multi-line history rendering in the REPL

Author: pablogsal

Lib/_pyrepl/historical_reader.py

@@ -264,6 +264,7 @@ def select_item(self, i: int) -> None:
         self.historyi = i
         self.pos = len(self.buffer)
         self.dirty = True
+        self.last_refresh_cache.invalidated = True
 
     def get_item(self, i: int) -> str:
         if i != len(self.history):

Lib/_pyrepl/reader.py

@@ -254,6 +254,7 @@ class RefreshCache:
         pos: int = field(init=False)
         cxy: tuple[int, int] = field(init=False)
         dimensions: tuple[int, int] = field(init=False)
+        invalidated: bool = False
 
         def update_cache(self,
                          reader: Reader,
@@ -266,14 +267,19 @@ def update_cache(self,
             self.pos = reader.pos
             self.cxy = reader.cxy
             self.dimensions = reader.console.width, reader.console.height
+            self.invalidated = False
 
         def valid(self, reader: Reader) -> bool:
+            if self.invalidated:
+                return False
             dimensions = reader.console.width, reader.console.height
             dimensions_changed = dimensions != self.dimensions
             paste_changed = reader.in_bracketed_paste != self.in_bracketed_paste
             return not (dimensions_changed or paste_changed)
 
         def get_cached_location(self, reader: Reader) -> tuple[int, int]:
+            if self.invalidated:
+                raise RuntimeError("Trying to use an invalid cache")
             offset = 0
             earliest_common_pos = min(reader.pos, self.pos)
             num_common_lines = len(self.line_end_offsets)

Lib/site.py

@@ -526,9 +526,8 @@ def register_readline():
 
         def write_history():
             try:
-                # _pyrepl.__main__ is executed as the __main__ module
-                from __main__ import CAN_USE_PYREPL
-            except ImportError:
+                from _pyrepl.main import CAN_USE_PYREPL
+            except ImportError as e:
                 CAN_USE_PYREPL = False
 
             try:

Lib/test/test_pyrepl/support.py

@@ -38,6 +38,16 @@ def code_to_events(code: str):
         yield Event(evt="key", data=c, raw=bytearray(c.encode("utf-8")))
 
 
+def clean_screen(screen: Iterable[str]):
+    """Cleans color and console characters out of a screen output.
+
+    This is useful for screen testing, it increases the test readability since
+    it strips out all the unreadable side of the screen.
+    """
+    return '\n'.join(screen).replace(
+        '\x1b[1;35m>>>\x1b[0m', '').replace('\x1b[1;35m...\x1b[0m', '').strip()
+
+
 def prepare_reader(console: Console, **kwargs):
     config = ReadlineConfig(readline_completer=kwargs.pop("readline_completer", None))
     reader = ReadlineAlikeReader(console=console, config=config)

Lib/test/test_pyrepl/test_pyrepl.py

@@ -17,6 +17,7 @@
     more_lines,
     multiline_input,
     code_to_events,
+    clean_screen
 )
 from _pyrepl.console import Event
 from _pyrepl.readline import ReadlineAlikeReader, ReadlineConfig
@@ -486,6 +487,7 @@ def test_basic(self):
 
         output = multiline_input(reader)
         self.assertEqual(output, "1+1")
+        self.assertEqual(clean_screen(reader.screen), "1+1")
 
     def test_multiline_edit(self):
         events = itertools.chain(
@@ -515,8 +517,10 @@ def test_multiline_edit(self):
 
         output = multiline_input(reader)
         self.assertEqual(output, "def f():\n    ...\n    ")
+        self.assertEqual(clean_screen(reader.screen), "def f():\n    ...")
         output = multiline_input(reader)
         self.assertEqual(output, "def g():\n    pass\n    ")
+        self.assertEqual(clean_screen(reader.screen), "def g():\n    pass")
 
     def test_history_navigation_with_up_arrow(self):
         events = itertools.chain(
@@ -535,12 +539,40 @@ def test_history_navigation_with_up_arrow(self):
 
         output = multiline_input(reader)
         self.assertEqual(output, "1+1")
+        self.assertEqual(clean_screen(reader.screen), "1+1")
         output = multiline_input(reader)
         self.assertEqual(output, "2+2")
+        self.assertEqual(clean_screen(reader.screen), "2+2")
         output = multiline_input(reader)
         self.assertEqual(output, "2+2")
+        self.assertEqual(clean_screen(reader.screen), "2+2")
         output = multiline_input(reader)
         self.assertEqual(output, "1+1")
+        self.assertEqual(clean_screen(reader.screen), "1+1")
+
+    def test_history_with_multiline_entries(self):
+        code = "def foo():\nx = 1\ny = 2\nz = 3\n\ndef bar():\nreturn 42\n\n"
+        events = list(itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+            ]
+        ))
+
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        output = multiline_input(reader)
+        output = multiline_input(reader)
+        self.assertEqual(
+            clean_screen(reader.screen),
+            'def foo():\n    x = 1\n    y = 2\n    z = 3'
+        )
+        self.assertEqual(output, "def foo():\n    x = 1\n    y = 2\n    z = 3\n    ")
+
 
     def test_history_navigation_with_down_arrow(self):
         events = itertools.chain(
@@ -558,6 +590,7 @@ def test_history_navigation_with_down_arrow(self):
 
         output = multiline_input(reader)
         self.assertEqual(output, "1+1")
+        self.assertEqual(clean_screen(reader.screen), "1+1")
 
     def test_history_search(self):
         events = itertools.chain(
@@ -574,18 +607,23 @@ def test_history_search(self):
 
         output = multiline_input(reader)
         self.assertEqual(output, "1+1")
+        self.assertEqual(clean_screen(reader.screen), "1+1")
         output = multiline_input(reader)
         self.assertEqual(output, "2+2")
+        self.assertEqual(clean_screen(reader.screen), "2+2")
         output = multiline_input(reader)
         self.assertEqual(output, "3+3")
+        self.assertEqual(clean_screen(reader.screen), "3+3")
         output = multiline_input(reader)
         self.assertEqual(output, "1+1")
+        self.assertEqual(clean_screen(reader.screen), "1+1")
 
     def test_control_character(self):
         events = code_to_events("c\x1d\n")
         reader = self.prepare_reader(events)
         output = multiline_input(reader)
         self.assertEqual(output, "c\x1d")
+        self.assertEqual(clean_screen(reader.screen), "c")
 
 
 class TestPyReplCompleter(TestCase):