tst_QImageReader: it's a rotate^Wadjacent_find!

Instead of copying a list, sorting it just to check it's sorted, and
making a QSet out of it just to check the size is the same as that of
the list (thereby checking there were no duplicates), simply apply
adjacent_find with greater_equal. If none of the elements is ≥ their
successor, that means all elements are < their successor, and _that_
means the range is sorted and has no duplicates.               q.e.d.

Pick-to: 6.6 6.5
Change-Id: Id73c674ad4e29117370e8fc6af9fdfc690a3fba9
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 18 insertions, 29 deletions

diff --git a/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp b/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp
index c8ef8ff839..10f3a813c3 100644
--- a/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp
+++ b/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp
@@ -11,7 +11,6 @@
 #include <QImageReader>
 #include <QImageWriter>
 #include <QPixmap>
-#include <QSet>
 #include <QScopeGuard>
 #include <QTcpSocket>
 #include <QTcpServer>
@@ -595,41 +594,31 @@ void tst_QImageReader::multiWordNamedColorXPM()
     QCOMPARE(image.pixel(0, 2), qRgb(255, 250, 205)); // lemon chiffon
 }
 
-void tst_QImageReader::supportedFormats()
+namespace {
+template <typename ForwardIterator>
+bool is_sorted_unique(ForwardIterator first, ForwardIterator last)
 {
-    QList<QByteArray> formats = QImageReader::supportedImageFormats();
-    QList<QByteArray> sortedFormats = formats;
-    std::sort(sortedFormats.begin(), sortedFormats.end());
-
-    // check that the list is sorted
-    QCOMPARE(formats, sortedFormats);
-
-    QSet<QByteArray> formatSet;
-    foreach (QByteArray format, formats)
-        formatSet << format;
+    // a range is sorted with no dups iff each *i < *(i+1), so check that none are >=:
+    return std::adjacent_find(first, last, std::greater_equal<>{}) == last;
+}
+}
 
-    // check that the list does not contain duplicates
-    QCOMPARE(formatSet.size(), formats.size());
+void tst_QImageReader::supportedFormats()
+{
+    const QList<QByteArray> formats = QImageReader::supportedImageFormats();
+    auto printOnFailure = qScopeGuard([&] { qDebug() << formats; });
+    QVERIFY(is_sorted_unique(formats.begin(), formats.end()));
+    printOnFailure.dismiss();
 }
 
 void tst_QImageReader::supportedMimeTypes()
 {
-    QList<QByteArray> mimeTypes = QImageReader::supportedMimeTypes();
-    QList<QByteArray> sortedMimeTypes = mimeTypes;
-    std::sort(sortedMimeTypes.begin(), sortedMimeTypes.end());
-
-    // check that the list is sorted
-    QCOMPARE(mimeTypes, sortedMimeTypes);
-
-    QSet<QByteArray> mimeTypeSet;
-    foreach (QByteArray mimeType, mimeTypes)
-        mimeTypeSet << mimeType;
-
+    const QList<QByteArray> mimeTypes = QImageReader::supportedMimeTypes();
+    auto printOnFailure = qScopeGuard([&] { qDebug() << mimeTypes; });
+    QVERIFY(is_sorted_unique(mimeTypes.begin(), mimeTypes.end()));
     // check the list as a minimum contains image/bmp
-    QVERIFY(mimeTypeSet.contains("image/bmp"));
-
-    // check that the list does not contain duplicates
-    QCOMPARE(mimeTypeSet.size(), mimeTypes.size());
+    QVERIFY(mimeTypes.contains("image/bmp"));
+    printOnFailure.dismiss();
 }
 
 void tst_QImageReader::setBackgroundColor_data()