}

  public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
    Builder<String, Integer> builder =
        new Builder<String, Integer>()
            .put("one", 1)
            .put("one", 1); // throwing on this line might be better but it's too late to change

    try {
      builder.buildOrThrow();
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

 * <p>Several methods in this class, such as {@link #readLines()}, break the contents of the source
 * into lines. Like {@link BufferedReader}, these methods break lines on any of {@code \n}, {@code
 * \r} or {@code \r\n}, do not include the line separator in each line and do not consider there to
 * be an empty line at the end if the contents are terminated with a line separator.
 *

    TestCharSource lines = new TestCharSource(LINES);
    assertEquals("foo", lines.readFirstLine());
    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());

    return ensureInUnitRange(sumOfProductsOfDeltas / Math.sqrt(productOfSumsOfSquaresOfDeltas));
  }

  /**
   * Returns a linear transformation giving the best fit to the data according to <a
   * href="http://mathworld.wolfram.com/LeastSquaresFitting.html">Ordinary Least Squares linear
   * regression</a> of {@code y} as a function of {@code x}. The count must be greater than one, and

org.checkerframework.checker.initialization
org.checkerframework.checker.initialization.qual
org.checkerframework.checker.interning
org.checkerframework.checker.interning.qual
org.checkerframework.checker.linear
org.checkerframework.checker.linear.qual
org.checkerframework.checker.lock
org.checkerframework.checker.lock.qual
org.checkerframework.checker.nullness
org.checkerframework.checker.nullness.compatqual

org.checkerframework.checker.initialization
org.checkerframework.checker.initialization.qual
org.checkerframework.checker.interning
org.checkerframework.checker.interning.qual
org.checkerframework.checker.linear
org.checkerframework.checker.linear.qual
org.checkerframework.checker.lock
org.checkerframework.checker.lock.qual
org.checkerframework.checker.nullness
org.checkerframework.checker.nullness.compatqual

  /** File separator ("/" on UNIX). */
  FILE_SEPARATOR("file.separator"),

  /** Path separator (":" on UNIX). */
  PATH_SEPARATOR("path.separator"),

  /** Line separator ("\n" on UNIX). */
  LINE_SEPARATOR("line.separator"),

  /** User's account name. */
  USER_NAME("user.name"),

  /** User's home directory. */
  USER_HOME("user.home"),

  /** User's current working directory. */

        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            if (line.length() > 0) {
              collector.add(line);
            }
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;
          }

   * @return a mutable {@link List} containing all the lines
   * @throws IOException if an I/O error occurs
   */
  public static List<String> readLines(Readable r) throws IOException {
    List<String> result = new ArrayList<>();
    LineReader lineReader = new LineReader(r);
    String line;
    while ((line = lineReader.readLine()) != null) {
      result.add(line);
    }
    return result;
  }

  /**

        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            collector.add(whitespace().trimFrom(line));
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;
          }
        };