jdk/test/jdk/java/nio/file/Files/StreamLinesTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/* @test
 * @bug 8072773
 * @library /test/lib
 * @build jdk.test.lib.RandomFactory
 * @run junit/othervm StreamLinesTest
 * @summary Tests streams returned from Files.lines, primarily focused on
 *          testing the file-channel-based stream stream with supported
 *          character sets
 * @key randomness
 */


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.EnumSet;
import java.util.List;
import java.util.Random;
import java.util.function.IntFunction;
import java.util.stream.Stream;
import jdk.test.lib.RandomFactory;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

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

public class StreamLinesTest {

    enum LineSeparator {
        NONE(""),
        N("\n"),
        R("\r"),
        RN("\r\n");

        public final String value;

        LineSeparator(String value) {
            this.value = value;
        }

        public String toString() {
            return name();
        }
    }

    static Path generateTempFileWithLines(IntFunction<String> lineGenerator,
                                          IntFunction<LineSeparator> lineSeparatorGenerator,
                                          int lines, Charset cs, boolean endLineSep) throws IOException {
        Path p = Files.createTempFile("lines", null);
        BufferedWriter bw = Files.newBufferedWriter(p, cs);

        for (int i = 0; i < lines - 1; i++) {
            bw.write(lineGenerator.apply(i));
            bw.write(lineSeparatorGenerator.apply(i).value);
        }
        if (lines > 0) {
            bw.write(lineGenerator.apply(lines - 1));
            if (endLineSep)
                bw.write(lineSeparatorGenerator.apply(lines - 1).value);
        }

        bw.flush();
        bw.close();
        p.toFile().deleteOnExit();

        return p;
    }

    static void writeLineSeparator(Path p,
                                   IntFunction<LineSeparator> lineSeparatorGenerator,
                                   int lines, Charset cs) throws IOException {
        BufferedWriter bw = Files.newBufferedWriter(p, cs, StandardOpenOption.APPEND);
        bw.write(lineSeparatorGenerator.apply(lines - 1).value);
        bw.flush();
        bw.close();
    }

    static List<String> readAllLines(Path path, Charset cs) throws IOException {
        try (BufferedReader reader = Files.newBufferedReader(path, cs)) {
            List<String> result = new ArrayList<>();
            for (; ; ) {
                String line = reader.readLine();
                if (line == null)
                    break;
                result.add(line);
            }
            return result;
        }
    }

    static Arguments of(String description, IntFunction<String> lineGenerator,
                       IntFunction<LineSeparator> separatorGenerator, int n, Charset cs) {
        return Arguments.argumentSet(description, lineGenerator, separatorGenerator, n, cs);
    }

    private static final Random random = RandomFactory.getRandom();

    static Stream<Arguments> lines() {
        List<Arguments> l = new ArrayList<>();

        // Include the three supported optimal-line charsets and one
        // which does not
        List<Charset> charsets = Arrays.asList(StandardCharsets.UTF_8,
                                               StandardCharsets.US_ASCII,
                                               StandardCharsets.ISO_8859_1,
                                               StandardCharsets.UTF_16);
        String[] lines = {"", "A", "AB", "ABC", "ABCD"};
        int[] linesSizes = {0, 1, 2, 3, 4, 16, 256, 1024};

        for (Charset charset : charsets) {
            for (int linesSize : linesSizes) {
                if (linesSize > 0) {
                    for (String line : lines) {
                        for (LineSeparator ls : EnumSet.complementOf(EnumSet.of(LineSeparator.NONE))) {
                            String description = String.format("%d lines of \"%s\" with separator %s", linesSize, line, ls);
                            l.add(of(description,
                                    i -> line,
                                    i -> ls,
                                    linesSize, charset));
                        }
                    }
                } else {
                    l.add(of("Empty file: 0 lines",
                            i -> "",
                            i -> LineSeparator.NONE,
                            0, charset));
                }
            }
        }

        for (Charset charset : charsets) {
            l.add(of("A maximum of 1024 random lines and separators",
                     i -> lines[1 + random.nextInt(lines.length - 1)],
                     i -> LineSeparator.values()[random.nextInt(LineSeparator.values().length)],
                     1024, charset));
        }

        for (Charset charset : charsets) {
            l.add(of("One large line with no separators",
                     i -> "ABCD",
                     i -> LineSeparator.NONE,
                     1024, charset));
        }

        return l.stream();
    }

    @ParameterizedTest
    @MethodSource("lines")
    public void test(IntFunction<String> lineGenerator, IntFunction<LineSeparator> separatorGenerator,
                     int lines, Charset cs) throws IOException {
        Path p = generateTempFileWithLines(lineGenerator, separatorGenerator, lines, cs, false);

        // Test without a separator at the end
        List<String> expected = readAllLines(p, cs);
        try (Stream<String> s = Files.lines(p, cs)) {
            assertEquals(expected, s.toList());
        }

        // Test with a separator at the end
        writeLineSeparator(p, separatorGenerator, lines, cs);
        expected = readAllLines(p, cs);
        try (Stream<String> s = Files.lines(p, cs)) {
            assertEquals(expected, s.toList());
        }
    }
}