### Question:
Writer implements StartsConstants { public static String pathToString(List<String> classPath) { long start = System.currentTimeMillis(); StringBuilder sb = new StringBuilder(); Iterator<String> iterator = classPath.iterator(); while (iterator.hasNext()) { sb.append(iterator.next()); if (iterator.hasNext()) { sb.append(File.pathSeparator); } } long end = System.currentTimeMillis(); LOGGER.log(Level.FINE, "[PROFILE] updateForNextRun(pathToString): " + millsToSeconds(end - start)); return sb.toString(); }  static void writeToFile(Collection col, String filename, String artifactsDir); static void writeToFile(Collection col, String filename); static void writeMapToFile(Map map, String filename); static void writeClassPath(String sfPathString, String artifactsDir); static void writeJarChecksums(List<String> sfPathString, String artifactsDir, List<Pair> jarCheckSums); static void writeGraph(DirectedGraph<String> graph, String artifactsDir, boolean print, String graphFile); static void writeDepsToFile(Map<String, Set<String>> deps, String fileName); static void writeTCSimple(Map<String, Set<String>> testDeps, String artifactsDir, String tcFile); static BufferedWriter getWriter(String filePath); static String pathToString(List<String> classPath); static List<String> fqnsToExcludePath(Collection<String> fqns); static String fqnToExcludePath(String fqn); static void writeToLog(Set<String> set, String title, Logger logger); static String millsToSeconds(long value); static Pair<String, String> getJarToChecksumMapping(String jar); static String urlToFQN(String url);  }### Answer:
@Test public void testPathToString() { List<String> list = new ArrayList<String>(); list.add("a"); list.add("b"); String result = "a" + File.pathSeparator + "b"; assertEquals(result, writer.pathToString(list)); }
@Test public void testEmptyPathToString() { List<String> list = new ArrayList<String>(); list.add(""); assertEquals("", writer.pathToString(list)); }
@Test public void testSinglePathToString() { List<String> list = new ArrayList<String>(); list.add("a"); assertEquals("a", writer.pathToString(list)); }