1 files changed, 49 insertions, 0 deletions
diff --git a/tests/auto/abstractoauth/tst_abstractoauth.cpp b/tests/auto/abstractoauth/tst_abstractoauth.cpp
index 36d04f8..a813574 100644
--- a/tests/auto/abstractoauth/tst_abstractoauth.cpp
+++ b/tests/auto/abstractoauth/tst_abstractoauth.cpp
@@ -42,6 +42,8 @@ private:
 
 private Q_SLOTS:
     void authorizationUrlSignal();
+    void generateRandomString_data();
+    void generateRandomString();
 };
 
 void tst_AbstractOAuth::authorizationUrlSignal()
@@ -59,5 +61,52 @@ void tst_AbstractOAuth::authorizationUrlSignal()
     QVERIFY(emitted);
 }
 
+void tst_AbstractOAuth::generateRandomString_data()
+{
+    QTest::addColumn<int>("length");
+    for (int i = 0; i <= 255; ++i)
+        QTest::addRow("%d", i) << i;
+}
+
+// copied from https://xkcd.com/221/
+int getRandomNumber()
+{
+    return 4;   // chosen by fair dice roll.
+                // guaranteed to be random.
+}
+
+void tst_AbstractOAuth::generateRandomString()
+{
+    struct Unprotected : public QAbstractOAuth {
+        using QAbstractOAuth::generateRandomString;
+    };
+
+    QFETCH(int, length);
+    QByteArray random1 = Unprotected::generateRandomString(length);
+    QCOMPARE(random1.size(), length);
+
+    // Check that it is truly random by repeating and checking that it is
+    // different. We don't try it for 1 and 2 characters because the chance of
+    // random coincidence is too high: 1 in 2^(6*n), so 1 in 64 and 1 in 4096
+    // respectively. For 3 characters, that decreases to 1 in 262,144.
+    if (length <= 2)
+        return;
+
+    QByteArray random2 = Unprotected::generateRandomString(length);
+    QCOMPARE_NE(random2, random1);
+
+    // Generate a Base64 string using getRandomNumber() random bytes. Base64
+    // encodes 6 bits per byte, so a 255-character string has 1530 bits of
+    // data.
+    char buf[192] = {};
+    int rawlen = (length * 6 + 7) / 8;
+    for (int i = 0; i < rawlen; ++i)
+        buf[i] = getRandomNumber();
+    QByteArray random3 = QByteArray(buf, rawlen).toBase64(QByteArray::Base64UrlEncoding);
+    Q_ASSERT(random3.size() >= length);
+    random3.truncate(length);
+    QCOMPARE_NE(random3, random1);
+}
+
 QTEST_MAIN(tst_AbstractOAuth)
 #include "tst_abstractoauth.moc"