[3.11] gh-79871: IDLE - Fix and test debugger module (GH-11451) (#112257)

Add docstrings to the debugger module. Fix two bugs: initialize Idb.botframe (should be in Bdb); In Idb.in_rpc_code, check whether prev_frame is None before trying to use it. Make other code changes.

Expand test_debugger coverage from 19% to 66%.
---------

(cherry picked from commit adedcfa06b553242d8033f6d9bebbcb3bc0dbb4d)

Co-authored-by: Anthony Shaw <anthony.p.shaw@gmail.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

5 files changed, 400 insertions, 77 deletions

diff --git a/Lib/idlelib/debugger.py b/Lib/idlelib/debugger.py
index a92bb98..f487b4c 100644
--- a/Lib/idlelib/debugger.py
+++ b/Lib/idlelib/debugger.py
@@ -1,3 +1,20 @@
+"""Debug user code with a GUI interface to a subclass of bdb.Bdb.
+
+The Idb idb and Debugger gui instances each need a reference to each
+other or to an rpc proxy for each other.
+
+If IDLE is started with '-n', so that user code and idb both run in the
+IDLE process, Debugger is called without an idb.  Debugger.__init__
+calls Idb with its incomplete self.  Idb.__init__ stores gui and gui
+then stores idb.
+
+If IDLE is started normally, so that user code executes in a separate
+process, debugger_r.start_remote_debugger is called, executing in the
+IDLE process.  It calls 'start the debugger' in the remote process,
+which calls Idb with a gui proxy.  Then Debugger is called in the IDLE
+for more.
+"""
+
 import bdb
 import os
 
@@ -10,66 +27,95 @@ from idlelib.window import ListedToplevel
 
 
 class Idb(bdb.Bdb):
+    "Supply user_line and user_exception functions for Bdb."
 
     def __init__(self, gui):
-        self.gui = gui  # An instance of Debugger or proxy of remote.
-        bdb.Bdb.__init__(self)
+        self.gui = gui  # An instance of Debugger or proxy thereof.
+        super().__init__()
 
     def user_line(self, frame):
-        if self.in_rpc_code(frame):
+        """Handle a user stopping or breaking at a line.
+
+        Convert frame to a string and send it to gui.
+        """
+        if _in_rpc_code(frame):
             self.set_step()
             return
-        message = self.__frame2message(frame)
+        message = _frame2message(frame)
         try:
             self.gui.interaction(message, frame)
         except TclError:  # When closing debugger window with [x] in 3.x
             pass
 
-    def user_exception(self, frame, info):
-        if self.in_rpc_code(frame):
+    def user_exception(self, frame, exc_info):
+        """Handle an the occurrence of an exception."""
+        if _in_rpc_code(frame):
             self.set_step()
             return
-        message = self.__frame2message(frame)
-        self.gui.interaction(message, frame, info)
-
-    def in_rpc_code(self, frame):
-        if frame.f_code.co_filename.count('rpc.py'):
-            return True
-        else:
-            prev_frame = frame.f_back
-            prev_name = prev_frame.f_code.co_filename
-            if 'idlelib' in prev_name and 'debugger' in prev_name:
-                # catch both idlelib/debugger.py and idlelib/debugger_r.py
-                # on both Posix and Windows
-                return False
-            return self.in_rpc_code(prev_frame)
-
-    def __frame2message(self, frame):
-        code = frame.f_code
-        filename = code.co_filename
-        lineno = frame.f_lineno
-        basename = os.path.basename(filename)
-        message = f"{basename}:{lineno}"
-        if code.co_name != "?":
-            message = f"{message}: {code.co_name}()"
-        return message
+        message = _frame2message(frame)
+        self.gui.interaction(message, frame, exc_info)
+
+def _in_rpc_code(frame):
+    "Determine if debugger is within RPC code."
+    if frame.f_code.co_filename.count('rpc.py'):
+        return True  # Skip this frame.
+    else:
+        prev_frame = frame.f_back
+        if prev_frame is None:
+            return False
+        prev_name = prev_frame.f_code.co_filename
+        if 'idlelib' in prev_name and 'debugger' in prev_name:
+            # catch both idlelib/debugger.py and idlelib/debugger_r.py
+            # on both Posix and Windows
+            return False
+        return _in_rpc_code(prev_frame)
+
+def _frame2message(frame):
+    """Return a message string for frame."""
+    code = frame.f_code
+    filename = code.co_filename
+    lineno = frame.f_lineno
+    basename = os.path.basename(filename)
+    message = f"{basename}:{lineno}"
+    if code.co_name != "?":
+        message = f"{message}: {code.co_name}()"
+    return message
 
 
 class Debugger:
-
-    vstack = vsource = vlocals = vglobals = None
+    """The debugger interface.
+
+    This class handles the drawing of the debugger window and
+    the interactions with the underlying debugger session.
+    """
+    vstack = None
+    vsource = None
+    vlocals = None
+    vglobals = None
+    stackviewer = None
+    localsviewer = None
+    globalsviewer = None
 
     def __init__(self, pyshell, idb=None):
+        """Instantiate and draw a debugger window.
+
+        :param pyshell: An instance of the PyShell Window
+        :type  pyshell: :class:`idlelib.pyshell.PyShell`
+
+        :param idb: An instance of the IDLE debugger (optional)
+        :type  idb: :class:`idlelib.debugger.Idb`
+        """
         if idb is None:
             idb = Idb(self)
         self.pyshell = pyshell
         self.idb = idb  # If passed, a proxy of remote instance.
         self.frame = None
         self.make_gui()
-        self.interacting = 0
+        self.interacting = False
         self.nesting_level = 0
 
     def run(self, *args):
+        """Run the debugger."""
         # Deal with the scenario where we've already got a program running
         # in the debugger and we want to start another. If that is the case,
         # our second 'run' was invoked from an event dispatched not from
@@ -104,12 +150,13 @@ class Debugger:
             self.root.after(100, lambda: self.run(*args))
             return
         try:
-            self.interacting = 1
+            self.interacting = True
             return self.idb.run(*args)
         finally:
-            self.interacting = 0
+            self.interacting = False
 
     def close(self, event=None):
+        """Close the debugger and window."""
         try:
             self.quit()
         except Exception:
@@ -127,6 +174,7 @@ class Debugger:
         self.top.destroy()
 
     def make_gui(self):
+        """Draw the debugger gui on the screen."""
         pyshell = self.pyshell
         self.flist = pyshell.flist
         self.root = root = pyshell.root
@@ -135,11 +183,11 @@ class Debugger:
         self.top.wm_iconname("Debug")
         top.wm_protocol("WM_DELETE_WINDOW", self.close)
         self.top.bind("<Escape>", self.close)
-        #
+
         self.bframe = bframe = Frame(top)
         self.bframe.pack(anchor="w")
         self.buttons = bl = []
-        #
+
         self.bcont = b = Button(bframe, text="Go", command=self.cont)
         bl.append(b)
         self.bstep = b = Button(bframe, text="Step", command=self.step)
@@ -150,14 +198,14 @@ class Debugger:
         bl.append(b)
         self.bret = b = Button(bframe, text="Quit", command=self.quit)
         bl.append(b)
-        #
+
         for b in bl:
             b.configure(state="disabled")
             b.pack(side="left")
-        #
+
         self.cframe = cframe = Frame(bframe)
         self.cframe.pack(side="left")
-        #
+
         if not self.vstack:
             self.__class__.vstack = BooleanVar(top)
             self.vstack.set(1)
@@ -180,20 +228,20 @@ class Debugger:
         self.bglobals = Checkbutton(cframe,
             text="Globals", command=self.show_globals, variable=self.vglobals)
         self.bglobals.grid(row=1, column=1)
-        #
+
         self.status = Label(top, anchor="w")
         self.status.pack(anchor="w")
         self.error = Label(top, anchor="w")
         self.error.pack(anchor="w", fill="x")
         self.errorbg = self.error.cget("background")
-        #
+
         self.fstack = Frame(top, height=1)
         self.fstack.pack(expand=1, fill="both")
         self.flocals = Frame(top)
         self.flocals.pack(expand=1, fill="both")
         self.fglobals = Frame(top, height=1)
         self.fglobals.pack(expand=1, fill="both")
-        #
+
         if self.vstack.get():
             self.show_stack()
         if self.vlocals.get():
@@ -204,7 +252,7 @@ class Debugger:
     def interaction(self, message, frame, info=None):
         self.frame = frame
         self.status.configure(text=message)
-        #
+
         if info:
             type, value, tb = info
             try:
@@ -223,28 +271,28 @@ class Debugger:
             tb = None
             bg = self.errorbg
         self.error.configure(text=m1, background=bg)
-        #
+
         sv = self.stackviewer
         if sv:
             stack, i = self.idb.get_stack(self.frame, tb)
             sv.load_stack(stack, i)
-        #
+
         self.show_variables(1)
-        #
+
         if self.vsource.get():
             self.sync_source_line()
-        #
+
         for b in self.buttons:
             b.configure(state="normal")
-        #
+
         self.top.wakeup()
         # Nested main loop: Tkinter's main loop is not reentrant, so use
         # Tcl's vwait facility, which reenters the event loop until an
-        # event handler sets the variable we're waiting on
+        # event handler sets the variable we're waiting on.
         self.nesting_level += 1
         self.root.tk.call('vwait', '::idledebugwait')
         self.nesting_level -= 1
-        #
+
         for b in self.buttons:
             b.configure(state="disabled")
         self.status.configure(text="")
@@ -288,8 +336,6 @@ class Debugger:
     def abort_loop(self):
         self.root.tk.call('set', '::idledebugwait', '1')
 
-    stackviewer = None
-
     def show_stack(self):
         if not self.stackviewer and self.vstack.get():
             self.stackviewer = sv = StackViewer(self.fstack, self.flist, self)
@@ -311,9 +357,6 @@ class Debugger:
         self.frame = stackitem[0]  # lineno is stackitem[1]
         self.show_variables()
 
-    localsviewer = None
-    globalsviewer = None
-
     def show_locals(self):
         lv = self.localsviewer
         if self.vlocals.get():
@@ -354,26 +397,32 @@ class Debugger:
         if gv:
             gv.load_dict(gdict, force, self.pyshell.interp.rpcclt)
 
-    def set_breakpoint_here(self, filename, lineno):
+    def set_breakpoint(self, filename, lineno):
+        """Set a filename-lineno breakpoint in the debugger.
+
+        Called from self.load_breakpoints and EW.setbreakpoint
+        """
         self.idb.set_break(filename, lineno)
 
-    def clear_breakpoint_here(self, filename, lineno):
+    def clear_breakpoint(self, filename, lineno):
         self.idb.clear_break(filename, lineno)
 
     def clear_file_breaks(self, filename):
         self.idb.clear_all_file_breaks(filename)
 
     def load_breakpoints(self):
-        "Load PyShellEditorWindow breakpoints into subprocess debugger"
+        """Load PyShellEditorWindow breakpoints into subprocess debugger."""
         for editwin in self.pyshell.flist.inversedict:
             filename = editwin.io.filename
             try:
                 for lineno in editwin.breakpoints:
-                    self.set_breakpoint_here(filename, lineno)
+                    self.set_breakpoint(filename, lineno)
             except AttributeError:
                 continue
 
+
 class StackViewer(ScrolledList):
+    "Code stack viewer for debugger GUI."
 
     def __init__(self, master, flist, gui):
         if macosx.isAquaTk():
@@ -414,12 +463,12 @@ class StackViewer(ScrolledList):
             self.select(index)
 
     def popup_event(self, event):
-        "override base method"
+        "Override base method."
         if self.stack:
             return ScrolledList.popup_event(self, event)
 
     def fill_menu(self):
-        "override base method"
+        "Override base method."
         menu = self.menu
         menu.add_command(label="Go to source line",
                          command=self.goto_source_line)
@@ -427,12 +476,12 @@ class StackViewer(ScrolledList):
                          command=self.show_stack_frame)
 
     def on_select(self, index):
-        "override base method"
+        "Override base method."
         if 0 <= index < len(self.stack):
             self.gui.show_frame(self.stack[index])
 
     def on_double(self, index):
-        "override base method"
+        "Override base method."
         self.show_source(index)
 
     def goto_source_line(self):
@@ -457,6 +506,7 @@ class StackViewer(ScrolledList):
 
 
 class NamespaceViewer:
+    "Global/local namespace viewer for debugger GUI."
 
     def __init__(self, master, title, dict=None):
         width = 0
@@ -544,6 +594,7 @@ class NamespaceViewer:
     def close(self):
         self.frame.destroy()
 
+
 if __name__ == "__main__":
     from unittest import main
     main('idlelib.idle_test.test_debugger', verbosity=2, exit=False)
diff --git a/Lib/idlelib/idle_test/test_debugger.py b/Lib/idlelib/idle_test/test_debugger.py
index 35efb34..db01a89 100644
--- a/Lib/idlelib/idle_test/test_debugger.py
+++ b/Lib/idlelib/idle_test/test_debugger.py
@@ -1,11 +1,279 @@
 "Test debugger, coverage 19%"
 
 from idlelib import debugger
-import unittest
-from test.support import requires
-requires('gui')
+from collections import namedtuple
+from textwrap import dedent
 from tkinter import Tk
 
+from test.support import requires
+import unittest
+from unittest import mock
+from unittest.mock import Mock, patch
+
+"""A test python script for the debug tests."""
+TEST_CODE = dedent("""
+    i = 1
+    i += 2
+    if i == 3:
+       print(i)
+    """)
+
+
+class MockFrame:
+    "Minimal mock frame."
+
+    def __init__(self, code, lineno):
+        self.f_code = code
+        self.f_lineno = lineno
+
+
+class IdbTest(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        cls.gui = Mock()
+        cls.idb = debugger.Idb(cls.gui)
+
+        # Create test and code objects to simulate a debug session.
+        code_obj = compile(TEST_CODE, 'idlelib/file.py', mode='exec')
+        frame1 = MockFrame(code_obj, 1)
+        frame1.f_back = None
+        frame2 = MockFrame(code_obj, 2)
+        frame2.f_back = frame1
+        cls.frame = frame2
+        cls.msg = 'file.py:2: <module>()'
+
+    def test_init(self):
+        # Test that Idb.__init_ calls Bdb.__init__.
+        idb = debugger.Idb(None)
+        self.assertIsNone(idb.gui)
+        self.assertTrue(hasattr(idb, 'breaks'))
+
+    def test_user_line(self):
+        # Test that .user_line() creates a string message for a frame.
+        self.gui.interaction = Mock()
+        self.idb.user_line(self.frame)
+        self.gui.interaction.assert_called_once_with(self.msg, self.frame)
+
+    def test_user_exception(self):
+        # Test that .user_exception() creates a string message for a frame.
+        exc_info = (type(ValueError), ValueError(), None)
+        self.gui.interaction = Mock()
+        self.idb.user_exception(self.frame, exc_info)
+        self.gui.interaction.assert_called_once_with(
+                self.msg, self.frame, exc_info)
+
+
+class FunctionTest(unittest.TestCase):
+    # Test module functions together.
+
+    def test_functions(self):
+        rpc_obj = compile(TEST_CODE,'rpc.py', mode='exec')
+        rpc_frame = MockFrame(rpc_obj, 2)
+        rpc_frame.f_back = rpc_frame
+        self.assertTrue(debugger._in_rpc_code(rpc_frame))
+        self.assertEqual(debugger._frame2message(rpc_frame),
+                         'rpc.py:2: <module>()')
+
+        code_obj = compile(TEST_CODE, 'idlelib/debugger.py', mode='exec')
+        code_frame = MockFrame(code_obj, 1)
+        code_frame.f_back = None
+        self.assertFalse(debugger._in_rpc_code(code_frame))
+        self.assertEqual(debugger._frame2message(code_frame),
+                         'debugger.py:1: <module>()')
+
+        code_frame.f_back = code_frame
+        self.assertFalse(debugger._in_rpc_code(code_frame))
+        code_frame.f_back = rpc_frame
+        self.assertTrue(debugger._in_rpc_code(code_frame))
+
+
+class DebuggerTest(unittest.TestCase):
+    "Tests for Debugger that do not need a real root."
+
+    @classmethod
+    def setUpClass(cls):
+        cls.pyshell = Mock()
+        cls.pyshell.root = Mock()
+        cls.idb = Mock()
+        with patch.object(debugger.Debugger, 'make_gui'):
+            cls.debugger = debugger.Debugger(cls.pyshell, cls.idb)
+        cls.debugger.root = Mock()
+
+    def test_cont(self):
+        self.debugger.cont()
+        self.idb.set_continue.assert_called_once()
+
+    def test_step(self):
+        self.debugger.step()
+        self.idb.set_step.assert_called_once()
+
+    def test_quit(self):
+        self.debugger.quit()
+        self.idb.set_quit.assert_called_once()
+
+    def test_next(self):
+        with patch.object(self.debugger, 'frame') as frame:
+            self.debugger.next()
+            self.idb.set_next.assert_called_once_with(frame)
+
+    def test_ret(self):
+        with patch.object(self.debugger, 'frame') as frame:
+            self.debugger.ret()
+            self.idb.set_return.assert_called_once_with(frame)
+
+    def test_clear_breakpoint(self):
+        self.debugger.clear_breakpoint('test.py', 4)
+        self.idb.clear_break.assert_called_once_with('test.py', 4)
+
+    def test_clear_file_breaks(self):
+        self.debugger.clear_file_breaks('test.py')
+        self.idb.clear_all_file_breaks.assert_called_once_with('test.py')
+
+    def test_set_load_breakpoints(self):
+        # Test the .load_breakpoints() method calls idb.
+        FileIO = namedtuple('FileIO', 'filename')
+
+        class MockEditWindow(object):
+            def __init__(self, fn, breakpoints):
+                self.io = FileIO(fn)
+                self.breakpoints = breakpoints
+
+        self.pyshell.flist = Mock()
+        self.pyshell.flist.inversedict = (
+            MockEditWindow('test1.py', [4, 4]),
+            MockEditWindow('test2.py', [13, 44, 45]),
+        )
+        self.debugger.set_breakpoint('test0.py', 1)
+        self.idb.set_break.assert_called_once_with('test0.py', 1)
+        self.debugger.load_breakpoints()  # Call set_breakpoint 5 times.
+        self.idb.set_break.assert_has_calls(
+            [mock.call('test0.py', 1),
+             mock.call('test1.py', 4),
+             mock.call('test1.py', 4),
+             mock.call('test2.py', 13),
+             mock.call('test2.py', 44),
+             mock.call('test2.py', 45)])
+
+    def test_sync_source_line(self):
+        # Test that .sync_source_line() will set the flist.gotofileline with fixed frame.
+        test_code = compile(TEST_CODE, 'test_sync.py', 'exec')
+        test_frame = MockFrame(test_code, 1)
+        self.debugger.frame = test_frame
+
+        self.debugger.flist = Mock()
+        with patch('idlelib.debugger.os.path.exists', return_value=True):
+            self.debugger.sync_source_line()
+        self.debugger.flist.gotofileline.assert_called_once_with('test_sync.py', 1)
+
+
+class DebuggerGuiTest(unittest.TestCase):
+    """Tests for debugger.Debugger that need tk root.
+
+    close needs debugger.top set in make_gui.
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        requires('gui')
+        cls.root = root = Tk()
+        root.withdraw()
+        cls.pyshell = Mock()
+        cls.pyshell.root = root
+        cls.idb = Mock()
+# stack tests fail with debugger here.
+##        cls.debugger = debugger.Debugger(cls.pyshell, cls.idb)
+##        cls.debugger.root = root
+##        # real root needed for real make_gui
+##        # run, interacting, abort_loop
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.root.destroy()
+        del cls.root
+
+    def setUp(self):
+        self.debugger = debugger.Debugger(self.pyshell, self.idb)
+        self.debugger.root = self.root
+        # real root needed for real make_gui
+        # run, interacting, abort_loop
+
+    def test_run_debugger(self):
+        self.debugger.run(1, 'two')
+        self.idb.run.assert_called_once_with(1, 'two')
+        self.assertEqual(self.debugger.interacting, 0)
+
+    def test_close(self):
+        # Test closing the window in an idle state.
+        self.debugger.close()
+        self.pyshell.close_debugger.assert_called_once()
+
+    def test_show_stack(self):
+        self.debugger.show_stack()
+        self.assertEqual(self.debugger.stackviewer.gui, self.debugger)
+
+    def test_show_stack_with_frame(self):
+        test_frame = MockFrame(None, None)
+        self.debugger.frame = test_frame
+
+        # Reset the stackviewer to force it to be recreated.
+        self.debugger.stackviewer = None
+        self.idb.get_stack.return_value = ([], 0)
+        self.debugger.show_stack()
+
+        # Check that the newly created stackviewer has the test gui as a field.
+        self.assertEqual(self.debugger.stackviewer.gui, self.debugger)
+        self.idb.get_stack.assert_called_once_with(test_frame, None)
+
+
+class StackViewerTest(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        requires('gui')
+        cls.root = Tk()
+        cls.root.withdraw()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.root.destroy()
+        del cls.root
+
+    def setUp(self):
+        self.code = compile(TEST_CODE, 'test_stackviewer.py', 'exec')
+        self.stack = [
+            (MockFrame(self.code, 1), 1),
+            (MockFrame(self.code, 2), 2)
+        ]
+        # Create a stackviewer and load the test stack.
+        self.sv = debugger.StackViewer(self.root, None, None)
+        self.sv.load_stack(self.stack)
+
+    def test_init(self):
+        # Test creation of StackViewer.
+        gui = None
+        flist = None
+        master_window = self.root
+        sv = debugger.StackViewer(master_window, flist, gui)
+        self.assertTrue(hasattr(sv, 'stack'))
+
+    def test_load_stack(self):
+        # Test the .load_stack() method against a fixed test stack.
+        # Check the test stack is assigned and the list contains the repr of them.
+        self.assertEqual(self.sv.stack, self.stack)
+        self.assertTrue('?.<module>(), line 1:' in self.sv.get(0))
+        self.assertEqual(self.sv.get(1), '?.<module>(), line 2: ')
+
+    def test_show_source(self):
+        # Test the .show_source() method against a fixed test stack.
+        # Patch out the file list to monitor it
+        self.sv.flist = Mock()
+        # Patch out isfile to pretend file exists.
+        with patch('idlelib.debugger.os.path.isfile', return_value=True) as isfile:
+            self.sv.show_source(1)
+            isfile.assert_called_once_with('test_stackviewer.py')
+            self.sv.flist.open.assert_called_once_with('test_stackviewer.py')
+
 
 class NameSpaceTest(unittest.TestCase):
 
@@ -23,7 +291,5 @@ class NameSpaceTest(unittest.TestCase):
         debugger.NamespaceViewer(self.root, 'Test')
 
 
-# Other classes are Idb, Debugger, and StackViewer.
-
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/Lib/idlelib/pyshell.py b/Lib/idlelib/pyshell.py
index 0a7ee59..3c3d715 100755
--- a/Lib/idlelib/pyshell.py
+++ b/Lib/idlelib/pyshell.py
@@ -133,8 +133,8 @@ class PyShellEditorWindow(EditorWindow):
     def __init__(self, *args):
         self.breakpoints = []
         EditorWindow.__init__(self, *args)
-        self.text.bind("<<set-breakpoint-here>>", self.set_breakpoint_here)
-        self.text.bind("<<clear-breakpoint-here>>", self.clear_breakpoint_here)
+        self.text.bind("<<set-breakpoint>>", self.set_breakpoint_event)
+        self.text.bind("<<clear-breakpoint>>", self.clear_breakpoint_event)
         self.text.bind("<<open-python-shell>>", self.flist.open_shell)
 
         #TODO: don't read/write this from/to .idlerc when testing
@@ -155,8 +155,8 @@ class PyShellEditorWindow(EditorWindow):
         ("Copy", "<<copy>>", "rmenu_check_copy"),
         ("Paste", "<<paste>>", "rmenu_check_paste"),
         (None, None, None),
-        ("Set Breakpoint", "<<set-breakpoint-here>>", None),
-        ("Clear Breakpoint", "<<clear-breakpoint-here>>", None)
+        ("Set Breakpoint", "<<set-breakpoint>>", None),
+        ("Clear Breakpoint", "<<clear-breakpoint>>", None)
     ]
 
     def color_breakpoint_text(self, color=True):
@@ -181,11 +181,11 @@ class PyShellEditorWindow(EditorWindow):
             self.breakpoints.append(lineno)
         try:    # update the subprocess debugger
             debug = self.flist.pyshell.interp.debugger
-            debug.set_breakpoint_here(filename, lineno)
+            debug.set_breakpoint(filename, lineno)
         except: # but debugger may not be active right now....
             pass
 
-    def set_breakpoint_here(self, event=None):
+    def set_breakpoint_event(self, event=None):
         text = self.text
         filename = self.io.filename
         if not filename:
@@ -194,7 +194,7 @@ class PyShellEditorWindow(EditorWindow):
         lineno = int(float(text.index("insert")))
         self.set_breakpoint(lineno)
 
-    def clear_breakpoint_here(self, event=None):
+    def clear_breakpoint_event(self, event=None):
         text = self.text
         filename = self.io.filename
         if not filename:
@@ -209,7 +209,7 @@ class PyShellEditorWindow(EditorWindow):
                         "insert lineend +1char")
         try:
             debug = self.flist.pyshell.interp.debugger
-            debug.clear_breakpoint_here(filename, lineno)
+            debug.clear_breakpoint(filename, lineno)
         except:
             pass
 
diff --git a/Lib/idlelib/stackviewer.py b/Lib/idlelib/stackviewer.py
index 4858cc6..f8e60fd 100644
--- a/Lib/idlelib/stackviewer.py
+++ b/Lib/idlelib/stackviewer.py
@@ -1,3 +1,5 @@
+# Rename to stackbrowser or possibly consolidate with browser.
+
 import linecache
 import os
 
diff --git a/Misc/NEWS.d/next/IDLE/2019-01-07-06-18-25.bpo-35668.JimxP5.rst b/Misc/NEWS.d/next/IDLE/2019-01-07-06-18-25.bpo-35668.JimxP5.rst
new file mode 100644
index 0000000..8bb5420
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2019-01-07-06-18-25.bpo-35668.JimxP5.rst
@@ -0,0 +1,4 @@
+Add docstrings to the IDLE debugger module. Fix two bugs:
+initialize Idb.botframe (should be in Bdb); in Idb.in_rpc_code,
+check whether prev_frame is None before trying to use it.
+Greatly expand test_debugger.