### Question:
DefaultProblem implements Problem { public String getSource() { return source; } DefaultProblem( String message, Severity severity, String source, int lineNumber, int columnNumber,
                                   Exception exception ); String getSource(); int getLineNumber(); int getColumnNumber(); String getLocation(); Exception getException(); String getMessage(); Severity getSeverity(); @Override String toString();  }### Answer:
@Test public void testGetSource() { DefaultProblem problem = new DefaultProblem( null, null, null, -1, -1, null ); assertEquals( "", problem.getSource() ); problem = new DefaultProblem( null, null, "", -1, -1, null ); assertEquals( "", problem.getSource() ); problem = new DefaultProblem( null, null, "SOURCE", -1, -1, null ); assertEquals( "SOURCE", problem.getSource() ); }