### Question:
NamedParamsDefault implements NamedParams { @Override public void copyParametersFrom( NamedParams aParam ) { if ( params != null && aParam != null ) { params.clear(); String[] keys = aParam.listParameters(); for ( int idx = 0; idx < keys.length; idx++ ) { String desc; try { desc = aParam.getParameterDescription( keys[idx] ); } catch ( UnknownParamException e ) { desc = ""; } String defValue; try { defValue = aParam.getParameterDefault( keys[idx] ); } catch ( UnknownParamException e ) { defValue = ""; } String value; try { value = aParam.getParameterValue( keys[idx] ); } catch ( UnknownParamException e ) { value = ""; } try { addParameterDefinition( keys[idx], defValue, desc ); } catch ( DuplicateParamException e ) { } setParameterValue( keys[idx], value ); } } } NamedParamsDefault(); @Override void addParameterDefinition( String key, String defValue, String description ); @Override String getParameterDescription( String key ); @Override String getParameterValue( String key ); @Override String getParameterDefault( String key ); @Override String[] listParameters(); @Override void setParameterValue( String key, String value ); @Override void eraseParameters(); @Override void clearParameters(); @Override void activateParameters(); @Override void copyParametersFrom( NamedParams aParam ); @Override void mergeParametersWith( NamedParams aParam, boolean replace );  }### Answer:
@Test public void testCopyParametersFromNullChecks() throws Exception { namedParams.copyParametersFrom( null ); NamedParams namedParams2 = new NamedParamsDefault(); ( (NamedParamsDefault) namedParams ).params = null; namedParams.copyParametersFrom( namedParams2 ); }
@Test public void testCopyParametersFrom() throws Exception { NamedParams namedParams2 = new NamedParamsDefault(); namedParams2.addParameterDefinition( "key", "default value", "description" ); namedParams2.setParameterValue( "key", "value" ); assertNull( namedParams.getParameterValue( "key" ) ); namedParams.copyParametersFrom( namedParams2 ); assertEquals( "value", namedParams.getParameterValue( "key" ) ); }