tst_QMessageAuthenticationCode: check that setKey() reset()s

It's documented as such.

Manual conflict resolutions:
  - QCryptographicHash::supportsAlgorithm() is 6.5+, remove the QSKIP

Change-Id: I7299d289117e52dcefe3c4ab917d7ecad6dd02be
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit a62aa1817863880fd340aab54d5b86aa4f8b1e53)
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 43 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qmessageauthenticationcode/tst_qmessageauthenticationcode.cpp b/tests/auto/corelib/tools/qmessageauthenticationcode/tst_qmessageauthenticationcode.cpp
index 3c8f8e13d1..277301ced1 100644
--- a/tests/auto/corelib/tools/qmessageauthenticationcode/tst_qmessageauthenticationcode.cpp
+++ b/tests/auto/corelib/tools/qmessageauthenticationcode/tst_qmessageauthenticationcode.cpp
@@ -37,6 +37,8 @@ class tst_QMessageAuthenticationCode : public QObject
 {
     Q_OBJECT
 private slots:
+    void repeated_setKey_data();
+    void repeated_setKey();
     void result_data();
     void result();
     void result_incremental_data();
@@ -47,6 +49,47 @@ private slots:
 
 Q_DECLARE_METATYPE(QCryptographicHash::Algorithm)
 
+void tst_QMessageAuthenticationCode::repeated_setKey_data()
+{
+    using A = QCryptographicHash::Algorithm;
+    QTest::addColumn<A>("algo");
+
+    const auto me = QMetaEnum::fromType<A>();
+    for (int i = 0, value; (value = me.value(i)) != -1; ++i)
+        QTest::addRow("%s", me.key(i)) << A(value);
+}
+
+void tst_QMessageAuthenticationCode::repeated_setKey()
+{
+    QFETCH(const QCryptographicHash::Algorithm, algo);
+
+    // GIVEN: two long keys, so we're sure the key needs to be hashed in order
+    //        to fit into the hash algorithm's block
+
+    static const QByteArray key1(1024, 'a');
+    static const QByteArray key2(2048, 'b');
+
+    // WHEN: processing the same message
+
+    QMessageAuthenticationCode macX(algo);
+    QMessageAuthenticationCode mac1(algo, key1);
+    QMessageAuthenticationCode mac2(algo, key2);
+
+    const auto check = [](QMessageAuthenticationCode &mac) {
+        mac.addData("This is nonsense, ignore it, please.");
+        return mac.result();
+    };
+
+    macX.setKey(key1);
+    QCOMPARE(check(macX), check(mac1));
+
+    // THEN: the result does not depend on whether a new QMAC instance was used
+    //       or an old one re-used (iow: setKey() reset()s)
+
+    macX.setKey(key2);
+    QCOMPARE(check(macX), check(mac2));
+}
+
 void tst_QMessageAuthenticationCode::result_data()
 {
     QTest::addColumn<QCryptographicHash::Algorithm>("algo");