Is it possible to use QCustomPlot in unit testing?

Question

I need to create a family of plots during a test of my program. I want to use QCustomPlot for such purposes, but I have a problem. For creating and saving my plot in the file, I have to create QApplication, after I need to reimplement my class from QMainWindow and after that, I can Use my QCustomPlot in the function that creates all needed plots and saves them in to file. Is it possible to avoid creating QApplication instance or QMainWindow instance or them both?

See code of my function below:

void MainWindow::print_image(std::vector<double> az, std::vector<double> el, std::vector<double> za, char *image_path){

QVector<double> azFunct;// =// QVector<double>::fromStdVector(az);
QVector<double> elFunct;// =// QVector<double>::fromStdVector(el);
QVector<double> zFunct = QVector<double>::fromStdVector(za);
QVector<double> xAxisValue(az.size());

//Filling axes of x with values
std::iota(xAxisValue.begin(),xAxisValue.end(),0);

QCustomPlot customPlot;

customPlot.setLocale(QLocale(QLocale::English, QLocale::UnitedKingdom)); // period as decimal separator and comma as thousand separator
customPlot.legend->setVisible(true);
QFont legendFont = font();  // start out with MainWindow's font..
legendFont.setPointSize(9); // and make a bit smaller for legend
customPlot.legend->setFont(legendFont);
customPlot.legend->setBrush(QBrush(QColor(255,255,255,230)));
// by default, the legend is in the inset layout of the main axis rect. So this is how we access it to change legend placement:
customPlot.axisRect()->insetLayout()->setInsetAlignment(0, Qt::AlignTop|Qt::AlignRight);

//Adding new graph for displaying, all on the same plot.
customPlot.addGraph(customPlot.yAxis, customPlot.xAxis);
customPlot.graph(0)->setPen(QPen(QColor(255, 100, 0)));
customPlot.graph(0)->setName("Azimuth function");

//Adding new graph for displaying, all on the same plot.
customPlot.addGraph();
customPlot.graph(1)->setPen(QPen(Qt::red));
customPlot.graph(1)->setName("Elevation function");

//Adding new graph for displaying, all on the same plot.
customPlot.addGraph();
customPlot.graph(2)->setPen(QPen(Qt::green));
customPlot.graph(2)->setName("Z-axis function");


for(int i = 0; i < az.size(); ++i){
    azFunct[i] = sin(az[i]*M_PI/180);
    elFunct[i] = cos(el[i]*M_PI/180);
}

double minZ = *std::min_element(zFunct.constBegin(), zFunct.constEnd());
double maxZ = *std::max_element(zFunct.constBegin(), zFunct.constEnd());

// pass data points to graphs:
customPlot.graph(0)->setData(xAxisValue, azFunct);
customPlot.graph(1)->setData(xAxisValue, elFunct);
customPlot.graph(2)->setData(xAxisValue,zFunct);

customPlot.xAxis->setVisible(true);
customPlot.xAxis->setTickLabels(false);
customPlot.xAxis2->setVisible(true);
customPlot.xAxis2->setTickLabels(false);
customPlot.yAxis2->setVisible(true);
// set ranges appropriate to show data:
customPlot.yAxis->setRange(-1, 1);
customPlot.yAxis2->setRange(minZ, maxZ);

customPlot.plotLayout()->insertRow(0);
//customPlot.plotLayout()->addElement(0, 0, new QCPTextElement(customPlot, "Z axis", QFont("sans", 12, QFont::Bold)));

// set labels:
customPlot.yAxis->setLabel("sin/cos value");
customPlot.yAxis2->setLabel("Z - axis");
//Under big question have to be tested!
customPlot.replot();
customPlot.savePng(QString(image_path),1500,500,1);}

score 0 · Answer 1 · answered Jul 15 '18 at 00:37

Of course you don't need a QMainWindow, you could instantiate a QCustomPlot instance by itself, not as a sub-widget of anything else. Furthermore, you don't need to show that widget to have it plot. So the tests can be non-interactive, even though they instantiate QApplication.

Of course, the design of QCustomPlot is broken; there's no need for it to be a QWidget. Only a particular view of a plot needs to be a widget. But that's another story.

Is it possible to use QCustomPlot in unit testing?

1 Answers1