QByteArray: make (ap|pre)pend(const QByteArray &) consider reserved

Append was previously optimized for lhs being empty but it should've
also taken into account if space had been reserved.
Apply the same optimization to prepend while we're at it.

Change-Id: I5e5d33a3189b9ad88d45e858a2ac412cbc294f79
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
index 2f0f5654ca..cf70a7bbaa 100644
--- a/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
+++ b/tests/auto/corelib/text/qbytearray/tst_qbytearray.cpp
@@ -838,6 +838,12 @@ void tst_QByteArray::prepend()
     QCOMPARE(ba.prepend(-1, 'x'), QByteArray("321foo"));
     QCOMPARE(ba.prepend(3, 'x'), QByteArray("xxx321foo"));
     QCOMPARE(ba.prepend("\0 ", 2), QByteArray::fromRawData("\0 xxx321foo", 11));
+
+    QByteArray tenChars;
+    tenChars.reserve(10);
+    QByteArray twoChars("ab");
+    tenChars.prepend(twoChars);
+    QCOMPARE(tenChars.capacity(), 10);
 }
 
 void tst_QByteArray::prependExtended_data()
@@ -882,6 +888,12 @@ void tst_QByteArray::append()
     QCOMPARE(ba.append("\0"), QByteArray("foo123xxx"));
     QCOMPARE(ba.append("\0", 1), QByteArray::fromRawData("foo123xxx\0", 10));
     QCOMPARE(ba.size(), 10);
+
+    QByteArray tenChars;
+    tenChars.reserve(10);
+    QByteArray twoChars("ab");
+    tenChars.append(twoChars);
+    QCOMPARE(tenChars.capacity(), 10);
 }
 
 void tst_QByteArray::appendExtended_data()