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pub fn join_with_conj(list: &[&str], conj: &str) -> String {
if list.is_empty() { panic!("Array should not be empty"); }
if list.len() == 1 { return String::from(list[0]); }
let first_ones: String = list[0..list.len() - 1].join(", ");
let last: &str = list.last().unwrap();
return format!("{} {} {}", first_ones, conj, last);
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
#[should_panic(expected = "Array should not be empty")]
fn panics_on_empty_array() {
let list: Vec<&str> = Vec::new();
let conj: &str = "whatever";
join_with_conj(&list, conj);
}
#[test]
fn does_not_add_conjunction_to_one_member_list() {
let list: Vec<&str> = vec!("Finnish");
let conj: &str = "and (which should not be printed)";
let expected = "Finnish";
let result = join_with_conj(&list, conj);
assert_eq!(result, expected);
}
#[test]
fn does_not_add_commas_to_two_member_list() {
let list: Vec<&str> = vec!("Finnish", "Karelian");
let conj: &str = "or";
let expected = "Finnish or Karelian";
let result = join_with_conj(&list, conj);
assert_eq!(result, expected);
}
#[test]
fn joins_with_and_conjunction() {
let list: Vec<&str> = vec!("Finnish", "Swedish", "Norwegian", "Danish");
let conj: &str = "and";
let expected = "Finnish, Swedish, Norwegian and Danish";
let result = join_with_conj(&list, conj);
assert_eq!(result, expected);
}
#[test]
fn joins_with_or_conjunction() {
let list: Vec<&str> = vec!("Finnish", "Swedish", "Norwegian", "Danish");
let conj: &str = "or worse";
let expected = "Finnish, Swedish, Norwegian or worse Danish";
let result = join_with_conj(&list, conj);
assert_eq!(result, expected);
}
}