if (expectedLines.isEmpty()) {
      assertThat(source.readFirstLine()).isNull();
    } else {
      assertThat(source.readFirstLine()).isEqualTo(expectedLines.get(0));
    }
  }

  public void testReadLines_toList() throws IOException {
    assertExpectedLines(source.readLines());
  }

  public void testIsEmpty() throws IOException {
    assertEquals(expected.isEmpty(), source.isEmpty());
  }

    TestCharSource lines = new TestCharSource(LINES);
    assertThat(lines.readFirstLine()).isEqualTo("foo");
    assertTrue(lines.wasStreamOpened() && lines.wasStreamClosed());
  }

  public void testReadLines_toList() throws IOException {
    TestCharSource lines = new TestCharSource(LINES);
    assertEquals(ImmutableList.of("foo", "bar", "baz", "something"), lines.readLines());