Line count kata at coding dojo

LineCountTest.scala

package linecount

import org.scalatest._
import matchers.ShouldMatchers

class LineCountTest extends FlatSpec with ShouldMatchers {

  "the Linecounter" should "think an empty string has zero lines" in {
    countLinesIn("") should equal(0)
  }

  it should "think a string with spaces has zero lines" in {
    countLinesIn("") should equal(0)
  }

  it should "count all the lines with text" in {
    countLinesIn(
      """while (true) do durgg();;
        |aa;
        |ee + 33;}""".stripMargin) should equal(3)
  }

  it should "ignore empty lines" in {
    countLinesIn(
      """while (true) do durgg();
        |
        |{
        | 1 ++
        |}
      """.stripMargin) should equal(4)
  }

  it should "ignore inline comments" in {
    countLinesIn(
      """while (true) do durgg();
        |
        |// ignore me
        |22 ++ // but not me
        |{
        |  i++
        |}
      """.stripMargin) should equal(5)
  }

  it should "ignore block comments" in {
    countLinesIn(
      """while (true) do durgg();
        |
        |/**  */
        |
        |/* comment
        |more comment
        |end comment *//***///inline
        |
        |/* don't ignore the command after this */ aCommand(); /* even with this comment after it */ //and this inline one
        |{
        |  i++
        |}
      """.stripMargin) should equal(5)
  }

  it should "ignore nested block comments" in {
    countLinesIn(
      """while (true) do durgg();
        |
        |    /* comment 1 /* /*
        |    comment 2
        |    */
        |    */
        |            */    <--
        |            */
        |
        |/* comment
        |more comment
        |end comment *//***///inline
        |
        |{
        |  i++
        |}
      """.stripMargin) should equal(7)
  }

  it should "correctly count Nigel's first file" in {
    countLinesIn(
      """// This file contains 3 lines of code
        |public interface Dave {
        |  /**
        |* count the number of lines in a file
        |*/
        |  int countLines(File inFile); // not the real signature!
        |}
      """.stripMargin) should equal(3)
  }

  it should "correctly count Nigel's second file" in {
    countLinesIn(
      """/*****
        |* This is a test program with 5 lines of code
        |* \/* no nesting allowed!
        |//*****//***/// Slightly pathological comment ending...
        |
        |  public class Hello {
        |      public static final void main(String [] args) { // gotta love Java
        |          // Say hello
        |        System./*wait*/out./*for*/println/*it*/("Hello/*");
        |      }
        |
        |}
      """.stripMargin) should equal(5)
  }


  def countLinesIn(text: String): Int = {
    val lines = removeBlockComments(text).split("\\n")
    lines.filter(notEmptyOrInlineComment).length
  }

  val notEmptyOrInlineComment: (String => Boolean) = line => {
    val trimmedLine = line.trim()
    trimmedLine.length > 0 && !trimmedLine.startsWith("//")
  }

  def removeBlockComments(text: String) = {
    val regexForBlockComments = "/\\*(\\n|.)*?\\*/"
    text.replaceAll(regexForBlockComments, "")
  }
}