Prepare gdb.python/mi-py-events.exp for Python/MI in separate channels

Similarly to 5068630ad34dce5fefbe68d70d3a50cd8b92f71e
(gdb.python/py-events.exp and normal_stop observers ordering) [1],
this commit makes the gdb.python/py-mi-events.exp test not rely on
order in which MI and Python observers run, or even on where each
observer sends its output to.

This shows up as a problem when testing with MI running as a separate
terminal, for example, where Python event output and MI output go to
different channels, even.  But in any case, relying on the order in
which observers run is always going to be fragile.

The fix is to save the string output in the handlers in some variables
and then having MI print them explicitly, instead of printing them
directly from the Python events.

Tested on x86_64 Fedora 23.

https://sourceware.org/ml/gdb-patches/2015-07/msg00290.html

gdb/testsuite/ChangeLog:
2016-06-21  Pedro Alves  <palves@redhat.com>

	* gdb.python/py-mi-events-gdb.py (stop_handler_str)
	(cont_handler_str): New.
	(signal_stop_handler): Set stop_handler_str instead of printing to
	stdout.
	(continue_handler): Set cont_handler_str instead of printing to
	stdout.
	* gdb.python/py-mi-events.exp: Ues mi_execute_to instead of
	mi_send_resuming_command.  Print stop_handler_str and
	cont_handler_str instead of expecting the python events print
	directly.

3 files changed, 33 insertions, 13 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e5f1c54..b33e1be 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,16 @@
+2016-06-21  Pedro Alves  <palves@redhat.com>
+
+	* gdb.python/py-mi-events-gdb.py (stop_handler_str)
+	(cont_handler_str): New.
+	(signal_stop_handler): Set stop_handler_str instead of printing to
+	stdout.
+	(continue_handler): Set cont_handler_str instead of printing to
+	stdout.
+	* gdb.python/py-mi-events.exp: Ues mi_execute_to instead of
+	mi_send_resuming_command.  Print stop_handler_str and
+	cont_handler_str instead of expecting the python events print
+	directly.
+
 2016-06-17  Sanjoy Das  <sanjoy@playingwithpointers.com>
 
 	* gdb.base/jit-reader.exp: New file.
diff --git a/gdb/testsuite/gdb.python/py-mi-events-gdb.py b/gdb/testsuite/gdb.python/py-mi-events-gdb.py
index 975ff2f..2bcb1fa 100644
--- a/gdb/testsuite/gdb.python/py-mi-events-gdb.py
+++ b/gdb/testsuite/gdb.python/py-mi-events-gdb.py
@@ -19,19 +19,23 @@
 
 import gdb
 
+stop_handler_str = ""
+cont_handler_str = ""
 
 def signal_stop_handler (event):
     """Stop event handler"""
     assert (isinstance (event, gdb.StopEvent))
-    print ("stop_handler")
-    print (gdb.execute("info break", False, True))
+    global stop_handler_str
+    stop_handler_str = "stop_handler\n"
+    stop_handler_str += gdb.execute("info break", False, True)
 
 
 def continue_handler (event):
     """Continue event handler"""
     assert (isinstance (event, gdb.ContinueEvent))
-    print ("continue_handler")
-    print (gdb.execute("info break", False, True))
+    global cont_handler_str
+    cont_handler_str = "continue_handler\n"
+    cont_handler_str += gdb.execute("info break", False, True)
 
 
 class test_events (gdb.Command):
diff --git a/gdb/testsuite/gdb.python/py-mi-events.exp b/gdb/testsuite/gdb.python/py-mi-events.exp
index 6f063e1..d20ae98 100644
--- a/gdb/testsuite/gdb.python/py-mi-events.exp
+++ b/gdb/testsuite/gdb.python/py-mi-events.exp
@@ -58,14 +58,16 @@ mi_gdb_test "test-events" \
     "register events"
 
 
+set lineno [gdb_get_line_number "i++;"]
+
 # set a breakpoint into the for loop
-mi_gdb_test "break ${srcfile}:[gdb_get_line_number "i++;"]" \
+mi_gdb_test "break ${srcfile}:$lineno" \
     ".*Breakpoint $decimal at 0x\[0-9a-fA-F\]+: file .*${srcfile}.*\\\.*\\^done" \
     "set the breakpoint"
 
 
 # resume the program
-mi_send_resuming_command "exec-continue" "continue"
+mi_execute_to "exec-continue" "breakpoint-hit" "main" "" ".*$srcfile" "$lineno" { "" "disp=\"keep\"" } "continue"
 
 
 # test the python event handlers execution. The following checks are performed:
@@ -73,12 +75,13 @@ mi_send_resuming_command "exec-continue" "continue"
 # - the continue handler prints "info breakpoints" output in console format
 # - breakpoint is hit and python stop handler is executed
 # - the stop handler prints "info breakpoints" output in console format
-mi_gdb_test "" ".*continue_handler.*
-.*Num.*Type.*Disp.*Enb.*Address.*\
-.*$decimal.*breakpoint.*keep.*y.* 0x\[0-9a-fA-F\]+.*${srcfile}.*
-.*stop_handler.*
-.*Num.*Type.*Disp.*Enb.*Address.*\
-.*$decimal.*breakpoint.*keep.*y.* 0x\[0-9a-fA-F\]+.*${srcfile}.*" \
-"check python continue and stop handlers"
+
+mi_gdb_test "python print (stop_handler_str)" \
+".*stop_handler.*Num.*Type.*Disp.*Enb.*Address.*$decimal.*breakpoint.*keep.*y.* 0x\[0-9a-fA-F\]+.*${srcfile}.*" \
+"python stop handler ran"
+
+mi_gdb_test "python print (cont_handler_str)" \
+".*continue_handler.*Num.*Type.*Disp.*Enb.*Address.*$decimal.*breakpoint.*keep.*y.* 0x\[0-9a-fA-F\]+.*${srcfile}.*" \
+"python continue handler ran"
 
 mi_gdb_exit