Use V4 double-to-string conversion instead of QVariant's

V4's version makes an effort to find the shortest possible
representation, which QVariant doesn't do.

Task-number: QTBUG-47070
Change-Id: I49ce130020496592325074e0db29a6984ee7649a
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

2 files changed, 32 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlproperty/data/floatToStringPrecision.qml b/tests/auto/qml/qqmlproperty/data/floatToStringPrecision.qml
new file mode 100644
index 0000000000..a0429e0cc8
--- /dev/null
+++ b/tests/auto/qml/qqmlproperty/data/floatToStringPrecision.qml
@@ -0,0 +1,10 @@
+import QtQuick 2.0
+
+QtObject {
+    property double a: 3.4
+    property string b: a
+
+    property double c: 0.035003945
+    property string d: c
+}
+
diff --git a/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp b/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
index d6b1c86b88..6ada14ce79 100644
--- a/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
+++ b/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
@@ -147,6 +147,7 @@ private slots:
     void registeredCompositeTypeProperty();
     void deeplyNestedObject();
     void readOnlyDynamicProperties();
+    void floatToStringPrecision();
 
     void copy();
 private:
@@ -2054,6 +2055,27 @@ void tst_qqmlproperty::readOnlyDynamicProperties()
     delete obj;
 }
 
+void tst_qqmlproperty::floatToStringPrecision()
+{
+    QQmlComponent comp(&engine, testFileUrl("floatToStringPrecision.qml"));
+    QObject *obj = comp.create();
+    QVERIFY(obj != 0);
+
+    QCOMPARE(obj->property("a").toDouble(), 3.4);
+    QEXPECT_FAIL("", "QVariant's double-to-string conversion is worse than V4's.", Continue);
+    QCOMPARE(obj->property("a").toString(), QLatin1String("3.4"));
+    QCOMPARE(obj->property("b").toDouble(), 3.4);
+    QCOMPARE(obj->property("b").toString(), QLatin1String("3.4"));
+
+    QCOMPARE(obj->property("c").toDouble(), 0.035003945);
+    QEXPECT_FAIL("", "QVariant's double-to-string conversion is worse than V4's.", Continue);
+    QCOMPARE(obj->property("c").toString(), QLatin1String("0.035003945"));
+    QCOMPARE(obj->property("d").toDouble(), 0.035003945);
+    QCOMPARE(obj->property("d").toString(), QLatin1String("0.035003945"));
+
+    delete obj;
+}
+
 void tst_qqmlproperty::initTestCase()
 {
     QQmlDataTest::initTestCase();