trunk/src/testcases/org/apache/poi/ss/formula/eval/forked/TestForkedEvaluator.java

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   this work for additional information regarding copyright ownership.
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package org.apache.poi.ss.formula.eval.forked;

import static org.junit.Assert.assertEquals;

import java.io.IOException;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.formula.IStabilityClassifier;
import org.apache.poi.ss.formula.eval.NumberEval;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

public class TestForkedEvaluator {
    
    @Rule
    public ExpectedException expectedEx = ExpectedException.none();
    
    protected Workbook newWorkbook() {
        return new HSSFWorkbook();
    }
    
	/**
	 * set up a calculation workbook with input cells nicely segregated on a
	 * sheet called "Inputs"
	 */
	protected Workbook createWorkbook() {
		Workbook wb = newWorkbook();
		Sheet sheet1 = wb.createSheet("Inputs");
		Sheet sheet2 = wb.createSheet("Calculations");
		Row row;
		row = sheet2.createRow(0);
		row.createCell(0).setCellFormula("B1*Inputs!A1-Inputs!B1");
		row.createCell(1).setCellValue(5.0); // Calculations!B1

		// some default input values
		row = sheet1.createRow(0);
		row.createCell(0).setCellValue(2.0); // Inputs!A1
		row.createCell(1).setCellValue(3.0); // Inputs!B1
		return wb;
	}

	/**
	 * Shows a basic use-case for {@link ForkedEvaluator}
	 */
	@Test
	public void testBasic() throws IOException {
		Workbook wb = createWorkbook();

		// The stability classifier is useful to reduce memory consumption of caching logic
		IStabilityClassifier stabilityClassifier = new IStabilityClassifier() {
			@Override
            public boolean isCellFinal(int sheetIndex, int rowIndex, int columnIndex) {
				return sheetIndex == 1;
			}
		};

		ForkedEvaluator fe1 = ForkedEvaluator.create(wb, stabilityClassifier, null);
		ForkedEvaluator fe2 = ForkedEvaluator.create(wb, stabilityClassifier, null);

		// fe1 and fe2 can be used concurrently on separate threads

		fe1.updateCell("Inputs", 0, 0, new NumberEval(4.0));
		fe1.updateCell("Inputs", 0, 1, new NumberEval(1.1));

		fe2.updateCell("Inputs", 0, 0, new NumberEval(1.2));
		fe2.updateCell("Inputs", 0, 1, new NumberEval(2.0));

		assertEquals(18.9, ((NumberEval) fe1.evaluate("Calculations", 0, 0)).getNumberValue(), 0.0);
		assertEquals(4.0, ((NumberEval) fe2.evaluate("Calculations", 0, 0)).getNumberValue(), 0.0);
		fe1.updateCell("Inputs", 0, 0, new NumberEval(3.0));
		assertEquals(13.9, ((NumberEval) fe1.evaluate("Calculations", 0, 0)).getNumberValue(), 0.0);
		
		wb.close();
	}

	/**
	 * As of Sep 2009, the Forked evaluator can update values from existing cells (this is because
	 * the underlying 'master' cell is used as a key into the calculation cache.  Prior to the fix
	 * for this bug, an attempt to update a missing cell would result in NPE.  This junit tests for
	 * a more meaningful error message.<br/>
	 *
	 * An alternate solution might involve allowing empty cells to be created as necessary.  That
	 * was considered less desirable because so far, the underlying 'master' workbook is strictly
	 * <i>read-only</i> with respect to the ForkedEvaluator.
	 */
	@Test
	public void testMissingInputCellH() throws IOException {
	    expectedEx.expect(UnsupportedOperationException.class);
	    expectedEx.expectMessage("Underlying cell 'A2' is missing in master sheet.");
	    
		Workbook wb = createWorkbook();

		try {
    		ForkedEvaluator fe = ForkedEvaluator.create(wb, null, null);
    		// attempt update input at cell A2 (which is missing)
            fe.updateCell("Inputs", 1, 0, new NumberEval(4.0));
		} finally {
		    wb.close();
		}
	}
}