Tests: add test for QuantitySpinBox::setValue(double)

tests/src/Gui/QuantitySpinBox.cpp

@@ -47,6 +47,24 @@ private Q_SLOTS:
         QCOMPARE(result, Base::Quantity(0.1, QLatin1String("mm")));
     }
 
+    void test_KeepFormat()  // NOLINT
+    {
+        auto quant = qsb->value();
+        auto format = quant.getFormat();
+        format.precision = 7;
+        quant.setFormat(format);
+
+        qsb->setValue(quant);
+
+        auto val1 = qsb->value();
+        QCOMPARE(val1.getFormat().precision, 7);
+
+        // format shoudn't change after setting a double
+        qsb->setValue(3.5);
+        auto val2 = qsb->value();
+        QCOMPARE(val2.getFormat().precision, 7);
+    }
+
 private:
     std::unique_ptr<Gui::QuantitySpinBox> qsb;
 };