### Question:
StringUtils { public static boolean isPackageFriendly(String moduleName) { return moduleName != null && PACKAGE_PATTERN.matcher(moduleName).matches(); }  static String arrayFormat(String format, Object[] items); static Optional<String> cdr(String name, String... sep); static String car(String name, String... sep); static String lastOf(String qualifiedName, String... sep); static String untill(String qualifiedName, String... sep); static String dotToUpperCamelCase(String input); static String dotToDash(String input); static String camelCaseToDash(String input); static boolean isPackageFriendly(String moduleName); static String withoutTypeArgs(String javaTypeString); static String notEmptytrimmed(String param); static Optional<Tuple<String, String>> splitIntoTwo(String mappingString); static int countMatches(String theString, String... sep);  }### Answer:
@Test void isPackageFriendly_boundary_cases() { assertFalse(isPackageFriendly(null)); }
@Test void testCheckPackageFriendly() { assertTrue(isPackageFriendly("a.b")); assertTrue(isPackageFriendly("a")); assertTrue(isPackageFriendly("a.b.c")); assertFalse(isPackageFriendly("a-b.c")); assertFalse(isPackageFriendly("0a.b.c")); }