### Question:
StringUtil { public static String trailingSlash(String value) { if (value == null || (value != null && value.endsWith("/"))) { return value; } return value.concat("/"); } private  StringUtil(); static String join(String separator, Iterable<?> elements); static String join(String separator, Object... elements); static String asString(final InputStream is, Charset charset); static String trailingSlash(String value); static String slug(String value);  }### Answer:
@Test(dataProvider = "validInputs") public void shouldAppendTrailingSlash(final String given, final String expected) { assertThat(trailingSlash(given)).isEqualTo(expected); }