while ((read = reader.read(buf)) != -1) {
      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    assertExpectedString(writer.toString());
  }

  public void testLines() throws IOException {
    try (Stream<String> lines = source.lines()) {
      assertExpectedLines(lines.collect(toImmutableList()));
    }
  }

  public void testCopyTo_appendable() throws IOException {

      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    assertTrue(source.wasStreamClosed());
    assertThat(writer.toString()).isEqualTo(STRING);
  }

  public void testLines() throws IOException {
    source = new TestCharSource(LINES);

    ImmutableList<String> lines;
    try (Stream<String> linesStream = source.lines()) {
      assertTrue(source.wasStreamOpened());

	{a: "abc\r\nabc", b: []string{"abc\r\n", "abc"}},
	{a: "abc\r\n", b: []string{"abc\r\n"}},
	{a: "\nabc", b: []string{"\n", "abc"}},
	{a: "\nabc\n\n", b: []string{"\n", "abc\n", "\n"}},
}

func TestLines(t *testing.T) {
	for _, s := range linesTests {
		result := sliceOfString(slices.Collect(Lines([]byte(s.a))))
		if !slices.Equal(result, s.b) {
			t.Errorf(`slices.Collect(Lines(%q)) = %q; want %q`, s.a, result, s.b)
		}

Ces validateurs personnalisés sont destinés aux éléments qui peuvent être vérifiés **uniquement** avec les **mêmes données** fournies dans la requête.

///

### Comprendre ce code { #understand-that-code }