[PATCH][gdb/testsuite] Reimplement gdb.gdb/python-interrupts.exp as unittest

[Tom de Vries via Gdb-patches <gdb-patches@sourceware.org>]

Hi,

The test-case gdb.gdb/python-interrupts.exp:
- runs to captured_command_loop
- sets a breakpoint at set_active_ext_lang
- calls a python command
- verifies the command triggers the breakpoint
- sends a signal and verifies the result

The test-case is fragile, because (f.i. with -flto) it cannot be guaranteed
that captured_command_loop and set_active_ext_lang are available for setting
breakpoints.

Reimplement the test-case as unittest, using:
- execute_command_to_string to capture the output
- try/catch to catch the "Error while executing Python code" exception
- a new hook selftests::hook_set_active_ext_lang to raise the signal

Tested on x86_64-linux.

Any comments?

Thanks,
- Tom

[gdb/testsuite] Reimplement gdb.gdb/python-interrupts.exp as unittest

---
 gdb/extension.c     | 12 +++++++++++
 gdb/python/python.c | 62 ++++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 59 insertions(+), 15 deletions(-)

diff --git a/gdb/extension.c b/gdb/extension.c
index 27dce9befa0..3edecb21d6b 100644
--- a/gdb/extension.c
+++ b/gdb/extension.c
@@ -682,6 +682,13 @@ install_gdb_sigint_handler (struct signal_handler *previous)
     previous->handler_saved = 0;
 }
 
+#if GDB_SELF_TEST
+namespace selftests {
+extern void (*hook_set_active_ext_lang) (void);
+void (*hook_set_active_ext_lang) (void) = nullptr;
+}
+#endif
+
 /* Set the currently active extension language to NOW_ACTIVE.
    The result is a pointer to a malloc'd block of memory to pass to
    restore_active_ext_lang.
@@ -708,6 +715,11 @@ install_gdb_sigint_handler (struct signal_handler *previous)
 struct active_ext_lang_state *
 set_active_ext_lang (const struct extension_language_defn *now_active)
 {
+#if GDB_SELF_TEST
+  if (selftests::hook_set_active_ext_lang)
+    selftests::hook_set_active_ext_lang ();
+#endif
+
   struct active_ext_lang_state *previous
     = XCNEW (struct active_ext_lang_state);
 
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 34c1be76a16..b17b6b69268 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1883,6 +1883,14 @@ do_start_initialization ()
 #if GDB_SELF_TEST
 namespace selftests {
 
+extern void (*hook_set_active_ext_lang) (void);
+
+static void
+raise_sigint (void)
+{
+  raise (SIGINT);
+}
+
 /* Entry point for python unit tests.  */
 
 static void
@@ -1897,21 +1905,45 @@ test_python ()
   output.clear ();
 
   bool saw_exception = false;
-  scoped_restore reset_gdb_python_initialized
-    = make_scoped_restore (&gdb_python_initialized, 0);
-  try
-    {
-      CMD (output);
-    }
-  catch (const gdb_exception &e)
-    {
-      saw_exception = true;
-      SELF_CHECK (e.reason == RETURN_ERROR);
-      SELF_CHECK (e.error == GENERIC_ERROR);
-      SELF_CHECK (*e.message == "Python not initialized");
-    }
-  SELF_CHECK (saw_exception);
-  SELF_CHECK (output.empty ());
+  {
+    scoped_restore reset_gdb_python_initialized
+      = make_scoped_restore (&gdb_python_initialized, 0);
+    try
+      {
+	CMD (output);
+      }
+    catch (const gdb_exception &e)
+      {
+	saw_exception = true;
+	SELF_CHECK (e.reason == RETURN_ERROR);
+	SELF_CHECK (e.error == GENERIC_ERROR);
+	SELF_CHECK (*e.message == "Python not initialized");
+      }
+    SELF_CHECK (saw_exception);
+    SELF_CHECK (output.empty ());
+  }
+
+  saw_exception = false;
+  {
+    scoped_restore save_hook
+      = make_scoped_restore (&hook_set_active_ext_lang, raise_sigint);
+    try
+      {
+	CMD (output);
+      }
+    catch (const gdb_exception &e)
+      {
+	saw_exception = true;
+	SELF_CHECK (e.reason == RETURN_ERROR);
+	SELF_CHECK (e.error == GENERIC_ERROR);
+	SELF_CHECK (*e.message == "Error while executing Python code.");
+      }
+    SELF_CHECK (saw_exception);
+    std::string ref_output("Traceback (most recent call last):\n"
+			   "  File \"<string>\", line 1, in <module>\n"
+			   "KeyboardInterrupt\n");
+    SELF_CHECK (output == ref_output);
+  }
 
 #undef CMD
 }