migration-test: Only hide error if !QTEST_LOG

The errors are very useful when debugging qtest failures, especially when
QTEST_LOG=1 is set.  Let's allow override MigrateStart.hide_stderr when
QTEST_LOG=1 is specified, because that means the user wants to be verbose.

Not very nice to introduce the first QTEST_LOG env access in migration-test.c,
however it should be handy.  Without this patch, I was hacking error_report()
when debugging such errors.  Let's make things easier.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201021212721.440373-7-peterx@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index f410ec5996..f2142fbd3c 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -464,6 +464,10 @@ static void migrate_postcopy_start(QTestState *from, QTestState *to)
 }
 
 typedef struct {
+    /*
+     * QTEST_LOG=1 may override this.  When QTEST_LOG=1, we always dump errors
+     * unconditionally, because it means the user would like to be verbose.
+     */
     bool hide_stderr;
     bool use_shmem;
     /* only launch the target process */
@@ -557,7 +561,7 @@ static int test_migrate_start(QTestState **from, QTestState **to,
 
     g_free(bootpath);
 
-    if (args->hide_stderr) {
+    if (!getenv("QTEST_LOG") && args->hide_stderr) {
         ignore_stderr = "2>/dev/null";
     } else {
         ignore_stderr = "";