TestNBitInteger.java

package test.codec.http2.hpack;

import static org.junit.Assert.assertEquals;

import java.nio.ByteBuffer;

import org.junit.Assert;
import org.junit.Test;

import com.firefly.codec.http2.hpack.NBitInteger;
import com.firefly.utils.io.BufferUtils;
import com.firefly.utils.lang.TypeUtils;

public class TestNBitInteger {

	@Test
	public void testOctetsNeeded() {
		assertEquals(0, NBitInteger.octectsNeeded(5, 10));
		assertEquals(2, NBitInteger.octectsNeeded(5, 1337));
		assertEquals(1, NBitInteger.octectsNeeded(8, 42));
		assertEquals(3, NBitInteger.octectsNeeded(8, 1337));

		assertEquals(0, NBitInteger.octectsNeeded(6, 62));
		assertEquals(1, NBitInteger.octectsNeeded(6, 63));
		assertEquals(1, NBitInteger.octectsNeeded(6, 64));
		assertEquals(2, NBitInteger.octectsNeeded(6, 63 + 0x00 + 0x80 * 0x01));
		assertEquals(3, NBitInteger.octectsNeeded(6, 63 + 0x00 + 0x80 * 0x80));
		assertEquals(4, NBitInteger.octectsNeeded(6, 63 + 0x00 + 0x80 * 0x80 * 0x80));
	}

	@Test
	public void testEncode() {
		testEncode(6, 0, "00");
		testEncode(6, 1, "01");
		testEncode(6, 62, "3e");
		testEncode(6, 63, "3f00");
		testEncode(6, 63 + 1, "3f01");
		testEncode(6, 63 + 0x7e, "3f7e");
		testEncode(6, 63 + 0x7f, "3f7f");
		testEncode(6, 63 + 0x00 + 0x80 * 0x01, "3f8001");
		testEncode(6, 63 + 0x01 + 0x80 * 0x01, "3f8101");
		testEncode(6, 63 + 0x7f + 0x80 * 0x01, "3fFf01");
		testEncode(6, 63 + 0x00 + 0x80 * 0x02, "3f8002");
		testEncode(6, 63 + 0x01 + 0x80 * 0x02, "3f8102");
		testEncode(6, 63 + 0x7f + 0x80 * 0x7f, "3fFf7f");
		testEncode(6, 63 + 0x00 + 0x80 * 0x80, "3f808001");
		testEncode(6, 63 + 0x7f + 0x80 * 0x80 * 0x7f, "3fFf807f");
		testEncode(6, 63 + 0x00 + 0x80 * 0x80 * 0x80, "3f80808001");

		testEncode(8, 0, "00");
		testEncode(8, 1, "01");
		testEncode(8, 128, "80");
		testEncode(8, 254, "Fe");
		testEncode(8, 255, "Ff00");
		testEncode(8, 255 + 1, "Ff01");
		testEncode(8, 255 + 0x7e, "Ff7e");
		testEncode(8, 255 + 0x7f, "Ff7f");
		testEncode(8, 255 + 0x80, "Ff8001");
		testEncode(8, 255 + 0x00 + 0x80 * 0x80, "Ff808001");
	}

	public void testEncode(int n, int i, String expected) {
		ByteBuffer buf = BufferUtils.allocate(16);
		int p = BufferUtils.flipToFill(buf);
		if (n < 8)
			buf.put((byte) 0x00);
		NBitInteger.encode(buf, n, i);
		BufferUtils.flipToFlush(buf, p);
		String r = TypeUtils.toHexString(BufferUtils.toArray(buf));
		assertEquals(expected, r);

		assertEquals(expected.length() / 2, (n < 8 ? 1 : 0) + NBitInteger.octectsNeeded(n, i));
	}

	@Test
	public void testDecode() {
		testDecode(6, 0, "00");
		testDecode(6, 1, "01");
		testDecode(6, 62, "3e");
		testDecode(6, 63, "3f00");
		testDecode(6, 63 + 1, "3f01");
		testDecode(6, 63 + 0x7e, "3f7e");
		testDecode(6, 63 + 0x7f, "3f7f");
		testDecode(6, 63 + 0x80, "3f8001");
		testDecode(6, 63 + 0x81, "3f8101");
		testDecode(6, 63 + 0x7f + 0x80 * 0x01, "3fFf01");
		testDecode(6, 63 + 0x00 + 0x80 * 0x02, "3f8002");
		testDecode(6, 63 + 0x01 + 0x80 * 0x02, "3f8102");
		testDecode(6, 63 + 0x7f + 0x80 * 0x7f, "3fFf7f");
		testDecode(6, 63 + 0x00 + 0x80 * 0x80, "3f808001");
		testDecode(6, 63 + 0x7f + 0x80 * 0x80 * 0x7f, "3fFf807f");
		testDecode(6, 63 + 0x00 + 0x80 * 0x80 * 0x80, "3f80808001");

		testDecode(8, 0, "00");
		testDecode(8, 1, "01");
		testDecode(8, 128, "80");
		testDecode(8, 254, "Fe");
		testDecode(8, 255, "Ff00");
		testDecode(8, 255 + 1, "Ff01");
		testDecode(8, 255 + 0x7e, "Ff7e");
		testDecode(8, 255 + 0x7f, "Ff7f");
		testDecode(8, 255 + 0x80, "Ff8001");
		testDecode(8, 255 + 0x00 + 0x80 * 0x80, "Ff808001");
	}

	public void testDecode(int n, int expected, String encoded) {
		ByteBuffer buf = ByteBuffer.wrap(TypeUtils.fromHexString(encoded));
		buf.position(n == 8 ? 0 : 1);
		Assert.assertEquals(expected, NBitInteger.decode(buf, n));
	}

	@Test
	public void testEncodeExampleD_1_1() {
		ByteBuffer buf = BufferUtils.allocate(16);
		int p = BufferUtils.flipToFill(buf);
		buf.put((byte) 0x77);
		buf.put((byte) 0xFF);
		NBitInteger.encode(buf, 5, 10);
		BufferUtils.flipToFlush(buf, p);

		String r = TypeUtils.toHexString(BufferUtils.toArray(buf));

		assertEquals("77Ea", r);

	}

	@Test
	public void testDecodeExampleD_1_1() {
		ByteBuffer buf = ByteBuffer.wrap(TypeUtils.fromHexString("77EaFF"));
		buf.position(2);

		Assert.assertEquals(10, NBitInteger.decode(buf, 5));
	}

	@Test
	public void testEncodeExampleD_1_2() {
		ByteBuffer buf = BufferUtils.allocate(16);
		int p = BufferUtils.flipToFill(buf);
		buf.put((byte) 0x88);
		buf.put((byte) 0x00);
		NBitInteger.encode(buf, 5, 1337);
		BufferUtils.flipToFlush(buf, p);

		String r = TypeUtils.toHexString(BufferUtils.toArray(buf));

		Assert.assertEquals("881f9a0a", r);

	}

	@Test
	public void testDecodeExampleD_1_2() {
		ByteBuffer buf = ByteBuffer.wrap(TypeUtils.fromHexString("881f9a0aff"));
		buf.position(2);

		Assert.assertEquals(1337, NBitInteger.decode(buf, 5));
	}

	@Test
	public void testEncodeExampleD_1_3() {
		ByteBuffer buf = BufferUtils.allocate(16);
		int p = BufferUtils.flipToFill(buf);
		buf.put((byte) 0x88);
		buf.put((byte) 0xFF);
		NBitInteger.encode(buf, 8, 42);
		BufferUtils.flipToFlush(buf, p);

		String r = TypeUtils.toHexString(BufferUtils.toArray(buf));

		Assert.assertEquals("88Ff2a", r);

	}

	@Test
	public void testDecodeExampleD_1_3() {
		ByteBuffer buf = ByteBuffer.wrap(TypeUtils.fromHexString("882aFf"));
		buf.position(1);

		Assert.assertEquals(42, NBitInteger.decode(buf, 8));
	}

}