TwoLoopsTest

import java.io.*;
import junit.framework.TestCase;

public class TwoLoopsTest extends TestCase {

    public void testGaganAjayBansal() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            GaganAjayBansal.main(new String[0]);
        });
        assertEquals("Expected System output;", multipleLines(
                "1 ",
                "1 2 1 ",
                "1 2 3 2 1 ",
                "1 2 3 4 3 2 1 ",
                "1 2 3 4 5 4 3 2 1 ",
                "1 2 3 4 5 6 5 4 3 2 1 ",
                "1 2 3 4 5 6 7 6 5 4 3 2 1 "),
                systemOutput);
    }

    public void testNiteshPatil() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            NiteshPatil.main(new String[0]);
        });
        assertEquals("Expected System output;", multipleLines(
                "1",
                "121",
                "12321",
                "1234321",
                "123454321",
                "12345654321",
                "1234567654321"),
                systemOutput);
    }

    public void testJeffGriggOneLoop_Default_is7() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            JeffGriggOneLoop.main(new String[0]);
        });
        assertEquals("Expected System output;", multipleLines(
                "1 ",
                "1 2 1 ",
                "1 2 3 2 1 ",
                "1 2 3 4 3 2 1 ",
                "1 2 3 4 5 4 3 2 1 ",
                "1 2 3 4 5 6 5 4 3 2 1 ",
                "1 2 3 4 5 6 7 6 5 4 3 2 1 "),
                systemOutput);
    }

    public void testJeffGriggOneLoop_printLinesWithValuesUpTo_3() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            JeffGriggOneLoop.printLinesWithValuesUpTo(3);
        });
        assertEquals("Expected System output;", multipleLines(
                "1 ",
                "1 2 1 ",
                "1 2 3 2 1 "),
                systemOutput);
    }

    public void testJeffGriggOneLoop_printLinesWithValuesUpTo_2() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            JeffGriggOneLoop.printLinesWithValuesUpTo(2);
        });
        assertEquals("Expected System output;", multipleLines(
                "1 ",
                "1 2 1 "),
                systemOutput);
    }

    public void testJeffGriggOneLoop_printLinesWithValuesUpTo_1() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            JeffGriggOneLoop.printLinesWithValuesUpTo(1);
        });
        assertEquals("Expected System output;", multipleLines(
                "1 "),
                systemOutput);
    }

    public void testJeffGriggOneLoop_printLinesWithValuesUpTo_ZERO_NoOutput() throws Exception {
        final String systemOutput = captureSystemOut(() -> {
            JeffGriggOneLoop.printLinesWithValuesUpTo(0);
        });
        assertEquals("Expected System output;", "", systemOutput);
    }

    private static String captureSystemOut(final Runnable runnable) throws IOException {
        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        try (final OutputStream os = outputStream) {
            final PrintStream oldSystemOut = System.out;
            try (final PrintStream outputPrintStream = new PrintStream(outputStream)) {
                System.setOut(outputPrintStream);
                try {
                    runnable.run();
                } finally {
                    System.setOut(oldSystemOut);
                }
            }
        }
        return outputStream.toString();
    }

    private String multipleLines(final String... lines) {
        final String lineSeparator = System.getProperty("line.separator");
        final StringBuilder result = new StringBuilder();
        for (final String line : lines) {
            result.append(line).append(lineSeparator);
        }
        return result.toString();
    }

}