Testlib: Fix minor leak and crash when comparing lists

1) toString does not track the string it returns, thus it has to be
deleted by the caller
2) on some platforms vsnprintf crashes if a null string is in the
va_list

Change-Id: Iecf94e93d3a2ddf4186ee20de1f495f2f92dcc60
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/src/testlib/qtest.h b/src/testlib/qtest.h
index 7c9a7b2b3f..7d2f3cea72 100644
--- a/src/testlib/qtest.h
+++ b/src/testlib/qtest.h
@@ -201,11 +201,17 @@ inline bool qCompare(QList<T> const &t1, QList<T> const &t2, const char *actual,
     }
     for (int i = 0; isOk && i < actualSize; ++i) {
         if (!(t1.at(i) == t2.at(i))) {
+            char *val1 = toString(t1.at(i));
+            char *val2 = toString(t2.at(i));
+
             qsnprintf(msg, sizeof(msg), "Compared lists differ at index %d.\n"
                       "   Actual   (%s): %s\n"
-                      "   Expected (%s): %s", i, actual, toString(t1.at(i)),
-                      expected, toString(t2.at(i)));
+                      "   Expected (%s): %s", i, actual, val1 ? val1 : "<null>",
+                      expected, val2 ? val2 : "<null>");
             isOk = false;
+
+            delete [] val1;
+            delete [] val2;
         }
     }
     return compare_helper(isOk, msg, 0, 0, actual, expected, file, line);