https://ch.mathworks.com/help/matlab/ref/matlab.unittest.diagnostics.figurediagnostic-class.html
matlab.unittest.diagnostics.FigureDiagnostic - Diagnostic to save specified figure - MATLAB
Use the matlab.unittest.diagnostics.FigureDiagnostic class to create a diagnostic for saving a MATLAB figure during a test run.
to savematlabunittestdiagnosticsfigure