[dexter] Correctly identify stop-reason while driving VisualStudio (#94754)

Prior to this patch VisualStudio._get_step_info incorrectly identifies
the reason the debugger has stopped. e.g., stepping through a program
would be reported as a StopReason.Breakpoint rather than
StopReason.Step.

Fix. No test added as there are no VisualStudio tests (tested locally).

cross-project-tests/debuginfo-tests/dexter/dex/debugger/visualstudio/VisualStudio.py

@@ -10,6 +10,7 @@ import abc
 import imp
 import os
 import sys
+from enum import IntEnum
 from pathlib import PurePath, Path
 from collections import defaultdict, namedtuple
 
@@ -37,6 +38,26 @@ def _load_com_module():
 VSBreakpoint = namedtuple("VSBreakpoint", "path, line, col, cond")
 
 
+# Visual Studio events.
+# https://learn.microsoft.com/en-us/dotnet/api/envdte.dbgeventreason?view=visualstudiosdk-2022
+class DbgEvent(IntEnum):
+    dbgEventReasonNone = 1
+    dbgEventReasonGo = 2
+    dbgEventReasonAttachProgram = 3
+    dbgEventReasonDetachProgram = 4
+    dbgEventReasonLaunchProgram = 5
+    dbgEventReasonEndProgram = 6
+    dbgEventReasonStopDebugging = 7
+    dbgEventReasonStep = 8
+    dbgEventReasonBreakpoint = 9
+    dbgEventReasonExceptionThrown = 10
+    dbgEventReasonExceptionNotHandled = 11
+    dbgEventReasonUserBreak = 12
+    dbgEventReasonContextSwitch = 13
+
+    first = dbgEventReasonNone
+    last = dbgEventReasonContextSwitch
+
 class VisualStudio(
     DebuggerBase, metaclass=abc.ABCMeta
 ):  # pylint: disable=abstract-method
@@ -307,6 +328,20 @@ class VisualStudio(
                 )
             )
 
+    def _translate_stop_reason(self, reason):
+        if reason == DbgEvent.dbgEventReasonNone:
+            return None
+        if reason == DbgEvent.dbgEventReasonBreakpoint:
+            return StopReason.BREAKPOINT
+        if reason == DbgEvent.dbgEventReasonStep:
+            return StopReason.STEP
+        if reason == DbgEvent.dbgEventReasonEndProgram:
+            return StopReason.PROGRAM_EXIT
+        if reason == DbgEvent.dbgEventReasonExceptionNotHandled:
+            return StopReason.ERROR
+        assert reason <= DbgEvent.last and reason >= DbgEvent.first
+        return StopReason.OTHER
+
     def _get_step_info(self, watches, step_index):
         thread = self._debugger.CurrentThread
         stackframes = thread.StackFrames
@@ -347,16 +382,13 @@ class VisualStudio(
             frames[0].loc = loc
             state_frames[0].location = SourceLocation(**self._location)
 
-        reason = StopReason.BREAKPOINT
-        if loc.path is None:  # pylint: disable=no-member
-            reason = StopReason.STEP
-
+        stop_reason = self._translate_stop_reason(self._debugger.LastBreakReason)
         program_state = ProgramState(frames=state_frames)
 
         return StepIR(
             step_index=step_index,
             frames=frames,
-            stop_reason=reason,
+            stop_reason=stop_reason,
             program_state=program_state,
         )