Fix racy output matching in gdb.base/completion.exp

Testing with:
 $ make check-read1 TESTS="gdb.base/completion.exp"

Exposes a testcase bug that can result in racy fails:

  FAIL: gdb.base/completion.exp: command-name completion limiting using tab character
  ERROR: Undefined command "".
  FAIL: gdb.base/completion.exp: symbol-name completion limiting using tab character
  FAIL: gdb.base/completion.exp: symbol-name completion limiting using complete command

testsuite/gdb.log shows:

  (gdb) PASS: gdb.base/completion.exp: set max-completions 5
  p^G
  passcount     path          print         print-object  printf
  *** List may be truncated, max-completions reached. ***
  (gdb) FAIL: gdb.base/completion.exp: command-name completion limiting using tab character
  pcomplete p
  Undefined command: "pcomplete".  Try "help".
  (gdb) ERROR: Undefined command "".

The problem is that the expect buffer can get filled with partial
output that ends in the gdb prompt, and so the default FAIL inside
gdb_test_multiple matches.

Fix that by splitting the gdb_test_multiple in two stages.  Since that
is done in more than one place in the testcase, move the otherwise
duplicate code to helper procedures.

gdb/testsuite/ChangeLog:
2017-11-09  Pedro Alves  <palves@redhat.com>

	* gdb.base/completion.exp (ignore_and_resync, test_tab_complete):
	New procedures, factored out from ...
	(top level): ... here, and adjusted to avoid expecting beyond the
	prompt in one go.

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 8566dc14aa30384dc3b3318f3ad97ac85d371bab..0886647daa38bf22c297c1a903f63a39c7081c3b 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2017-11-09  Pedro Alves  <palves@redhat.com>
+
+       * gdb.base/completion.exp (ignore_and_resync, test_tab_complete):
+       New procedures, factored out from ...
+       (top level): ... here, and adjusted to avoid expecting beyond the
+       prompt in one go.
+
 2017-11-09  Pedro Alves  <palves@redhat.com>
 
        * gdb.asm/asm-source.exp ("kill" test): Match the whole query

diff --git a/gdb/testsuite/gdb.base/completion.exp b/gdb/testsuite/gdb.base/completion.exp
index f03bfc3ea217e0c9d5fcdd6859f103afd9c7b921..9c7c17a0d1dc5c2314c3ba91865d9d6f8f221077 100644 (file)
--- a/gdb/testsuite/gdb.base/completion.exp
+++ b/gdb/testsuite/gdb.base/completion.exp
@@ -863,36 +863,45 @@ gdb_test "complete break $srcfile:ma" "break\.c:main"
 
 gdb_test_no_output "set max-completions 5"
 
-set test "command-name completion limiting using tab character"
-send_gdb "p\t"
-gdb_test_multiple "" "$test" {
-    -re "^p\\\x07$" {
-       send_gdb "\t"
-       gdb_test_multiple "" "$test" {
-           -re "List may be truncated, max-completions reached.*\r\n$gdb_prompt p$" {
-               # Complete the command and ignore the output to resync
-               # gdb for the next test.
-               send_gdb "\n"
-               gdb_test_multiple "" "$test" {
-                   -re "$gdb_prompt $" {
-                       pass "$test"
-                   }
+proc ignore_and_resync {cmd result test} {
+    global gdb_prompt
+
+    gdb_test_multiple "" "$test" {
+       -re "^${cmd}$" {
+           # Complete the command and ignore the output
+           # to resync gdb for the next test.
+           send_gdb "\n"
+           gdb_test_multiple "" "$test" {
+               -re "$gdb_prompt $" {
+                   $result $test
                }
            }
-           -re "$gdb_prompt p$" {
-               # Complete the command and ignore the output to resync
-               # gdb for the next test.
-               send_gdb "\n"
-               gdb_test_multiple "" "$test" {
-                   -re "$gdb_prompt $" {
-                       fail "$test"
-                   }
+       }
+    }
+}
+
+proc test_tab_complete {cmd test} {
+    global gdb_prompt
+
+    send_gdb "${cmd}\t"
+    gdb_test_multiple "" "$test" {
+       -re "^${cmd}\\\x07$" {
+           send_gdb "\t"
+           gdb_test_multiple "" "$test" {
+               -re "List may be truncated, max-completions reached.*\r\n$gdb_prompt " {
+                   ignore_and_resync $cmd pass $test
+               }
+               -re "$gdb_prompt " {
+                   ignore_and_resync $cmd fail $test
                }
            }
-        }
+       }
     }
 }
 
+test_tab_complete "p" \
+    "command-name completion limiting using tab character"
+
 set test "command-name completion limiting using complete command"
 send_gdb "complete p\n"
 gdb_test_multiple "" "$test" {
@@ -903,35 +912,8 @@ gdb_test_multiple "" "$test" {
 
 gdb_test_no_output "set max-completions 3"
 
-set test "symbol-name completion limiting using tab character"
-send_gdb "p marker\t"
-gdb_test_multiple "" "$test" {
-    -re "^p marker\\\x07$" {
-       send_gdb "\t"
-       gdb_test_multiple "" "$test" {
-           -re "List may be truncated, max-completions reached.*\r\n$gdb_prompt p marker$" {
-               # Complete the command and ignore the output to resync
-               # gdb for the next test.
-               send_gdb "\n"
-               gdb_test_multiple "" "$test" {
-                   -re "$gdb_prompt $" {
-                       pass "$test"
-                   }
-               }
-           }
-           -re "$gdb_prompt p marker$" {
-               # Complete the command and ignore the output to resync
-               # gdb for the next test.
-               send_gdb "\n"
-               gdb_test_multiple "" "$test" {
-                   -re "$gdb_prompt $" {
-                       fail "$test"
-                   }
-               }
-           }
-        }
-    }
-}
+test_tab_complete "p marker" \
+    "symbol-name completion limiting using tab character"
 
 set test "symbol-name completion limiting using complete command"
 send_gdb "complete p mark\n"