### Question:
PromotionBuilder { public PromotionBuilder timestampDate(Date timestampDate) { if (timestampDate == null) { throw new IllegalArgumentException("Cannot format a null date."); } this.timestamp = new SimpleDateFormat(Build.STARTED_FORMAT).format(timestampDate); return this; } PromotionBuilder(); PromotionBuilder status(String status); PromotionBuilder comment(String comment); PromotionBuilder ciUser(String ciUser); PromotionBuilder timestamp(String timestamp); PromotionBuilder timestampDate(Date timestampDate); PromotionBuilder dryRun(boolean dryRun); PromotionBuilder targetRepo(String targetRepo); PromotionBuilder sourceRepo(String sourceRepo); PromotionBuilder copy(boolean copy); PromotionBuilder artifacts(boolean artifacts); PromotionBuilder dependencies(boolean dependencies); PromotionBuilder scopes(Set<String> scopes); PromotionBuilder addScope(String scope); PromotionBuilder properties(Map<String, Collection<String>> properties); PromotionBuilder addProperty(String key, String value); PromotionBuilder failFast(boolean failFast); Promotion build(); boolean isFailFast();  }### Answer:
@Test(expectedExceptions = IllegalArgumentException.class) public void testNullDateForTimestamp() { new PromotionBuilder().timestampDate(null); }