### Question:
Strings { public static String toCsv(List<String> src) { return join(src, ", "); } private  Strings(); static String toCsv(List<String> src); static String join(List<String> src, String delimiter); static String capitaliseFirstLetter(String string); static String lowercaseFirstLetter(String string); static String zeros(int n); static String repeat(char value, int n); static boolean isEmpty(String s);  }### Answer:
@Test public void testToCsv() { assertThat(toCsv(Collections.<String>emptyList()), is("")); assertThat(toCsv(Collections.singletonList("a")), is("a")); assertThat(toCsv(Arrays.asList("a", "b", "c")), is("a, b, c")); }
@Test public void testToCsv() { assertEquals(toCsv(Collections.<String>emptyList()), ("")); assertEquals(toCsv(Collections.singletonList("a")), ("a")); assertEquals(toCsv(Arrays.asList("a", "b", "c")), ("a, b, c")); }