Add a test to SensorDataModelTest to ensure QTransposeProxyModel is correct

Commit 74db33b1 reported QTransposeProxyModel as broken. Since the code
has now changed again, let's make sure we verify that things still work
correctly.

autotests/sensordatamodeltest.cpp

@@ -20,6 +20,7 @@
 
 #include <QTest>
 #include <QAbstractItemModelTester>
+#include <QTransposeProxyModel>
 
 #include <QDBusInterface>
 
@@ -94,6 +95,28 @@ private Q_SLOTS:
         QCOMPARE(model.headerData(1, Qt::Horizontal, unit).value<KSysGuard::Unit>(), KSysGuard::UnitByteRate);
         QCOMPARE(model.headerData(2, Qt::Horizontal, unit).value<KSysGuard::Unit>(), KSysGuard::UnitPercent);
     }
+
+    void testTransposeProxy()
+    {
+        KSysGuard::SensorDataModel model;
+        QAbstractItemModelTester tester{&model};
+        Q_UNUSED(tester)
+
+        QTransposeProxyModel transpose;
+        transpose.setSourceModel(&model);
+
+        model.setSensors({
+            qs("cpu/all/usage"),
+            qs("memory/physical/used"),
+            qs("network/all/download"),
+            qs("disk/all/used")
+        });
+
+        QTRY_VERIFY(model.isReady());
+
+        QCOMPARE(model.columnCount(), transpose.rowCount());
+        QCOMPARE(model.rowCount(), transpose.columnCount());
+    }
 };
 
 QTEST_MAIN(SensorDataModelTest);