poi-examples/src/test/java/org/apache/poi/integration/TestXLSX2CSV.java

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   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.integration;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import org.apache.poi.examples.xssf.eventusermodel.XLSX2CSV;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.openxml4j.opc.PackageAccess;
import org.apache.poi.xssf.XSSFTestDataSamples;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class TestXLSX2CSV {
	private PrintStream err;
	private final ByteArrayOutputStream errorBytes = new ByteArrayOutputStream();

	@BeforeEach
	public void setUp() {
		// remember and replace default error streams
		err = System.err;

		PrintStream error = new PrintStream(errorBytes);
		System.setErr(error);
	}

	@AfterEach
	public void tearDown() throws Exception {
		// restore output-streams again
		System.setErr(err);

		// Print out found error
		if (errorBytes.size() > 0) {
			System.err.println("Had stderr: " + errorBytes.toString("UTF-8"));
		}
	}

	@Test
	public void testNoArgument() throws Exception {
		// returns with some System.err
		XLSX2CSV.main(new String[0]);

		String output = errorBytes.toString("UTF-8");
		assertTrue(output.contains("XLSX2CSV <xlsx file>"), "Had: " + output);
	}

	@Test
	public void testInvalidFile() throws Exception {
		// returns with some System.err
		XLSX2CSV.main(new String[] { "not-existing-file.xlsx" });

		String output = errorBytes.toString("UTF-8");
		assertTrue(output.contains("Not found or not a file: not-existing-file.xlsx"), "Had: " + output);
	}

	@Test
	public void testSampleFile() throws Exception {
		final ByteArrayOutputStream outputBytes = new ByteArrayOutputStream();
		PrintStream out = new PrintStream(outputBytes);

		// The package open is instantaneous, as it should be.
		try (OPCPackage p = OPCPackage.open(XSSFTestDataSamples.getSampleFile("sample.xlsx").getAbsolutePath(), PackageAccess.READ)) {
			XLSX2CSV xlsx2csv = new XLSX2CSV(p, out, -1);
			xlsx2csv.process();
		}

		String errorOutput = errorBytes.toString("UTF-8");
		assertEquals(errorOutput.length(), 0);

		String output = outputBytes.toString("UTF-8");
		assertTrue(output.contains("\"Lorem\",111"), "Had: " + output);
		assertTrue(output.contains(",\"hello, xssf\",,\"hello, xssf\""), "Had: " + output);
	}

	@Test
	public void testMinColumns() throws Exception {
		final ByteArrayOutputStream outputBytes = new ByteArrayOutputStream();
		PrintStream out = new PrintStream(outputBytes);

		// The package open is instantaneous, as it should be.
		try (OPCPackage p = OPCPackage.open(XSSFTestDataSamples.getSampleFile("sample.xlsx").getAbsolutePath(), PackageAccess.READ)) {
			XLSX2CSV xlsx2csv = new XLSX2CSV(p, out, 5);
			xlsx2csv.process();
		}

		String errorOutput = errorBytes.toString("UTF-8");
		assertEquals(errorOutput.length(), 0);

		String output = outputBytes.toString("UTF-8");
		assertTrue(output.contains("\"Lorem\",111,,,"), "Had: " + output);
		assertTrue(output.contains(",\"hello, xssf\",,\"hello, xssf\","), "Had: " + output);
	}
}