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#[cfg(test)]
pub mod test_utils {
/// Return true iff `s` contains exactly one occurrence of substring `t`.
pub fn contains_once(s: &str, t: &str) -> bool {
match (s.find(t), s.rfind(t)) {
(Some(i), Some(j)) => i == j,
_ => false,
}
}
#[allow(dead_code)]
pub fn print_with_line_numbers(s: &str) {
for (i, t) in s.lines().enumerate() {
println!("{:>2}│ {}", i + 1, t);
}
}
}
#[cfg(test)]
mod tests {
use crate::tests::test_utils::test_utils::*;
#[test]
fn test_contains_once_1() {
assert!(contains_once("", ""));
}
#[test]
fn test_contains_once_2() {
assert!(contains_once("a", "a"));
}
#[test]
fn test_contains_once_3() {
assert!(!contains_once("", "a"));
}
#[test]
fn test_contains_once_4() {
assert!(!contains_once("a", "b"));
}
#[test]
fn test_contains_once_5() {
assert!(!contains_once("a a", "a"));
}
#[test]
fn test_contains_once_6() {
assert!(contains_once("a b", "b"));
}
}
|
