Wrong test in haspmaps3.rs exercise

[cscherrNT]

While solving the rustlings to learn the Language, I think i found a wrongly configured test in exercises/hashmaps/hashmaps3.rs

    fn get_results() -> String {                                                                    
        let results = "".to_string()                                                                
            + "England,France,4,2\n"                                                                
            + "France,Italy,3,1\n"                                                                  
            + "Poland,Spain,2,0\n"                                                                  
            + "Germany,England,2,1\n";  // <---- This line says England scored 1 and conceided 2.                                                            
        results                                                                                     
    }
// some other test ...
    #[test]
    fn validate_team_score_1() {
        let scores = build_scores_table(get_results());
        let team = scores.get("England").unwrap();
        assert_eq!(team.goals_scored, 5); // <---- Yet this and the following lines say that England should have scored 5 and conceded 4.
        assert_eq!(team.goals_conceded, 4); // ( affected aswell )
    }

This of course makes solving the challenge with logical code impossible.

Proposed fix:

    fn get_results() -> String {                                                                    
        let results = "".to_string()                                                                
            + "England,France,4,2\n"                                                                
            + "France,Italy,3,1\n"                                                                  
            + "Poland,Spain,2,0\n"                                                                  
            + "Germany,England,2,1\n";  // <---- This line says England scored 1 and conceided 2.                                                            
        results                                                                                     
    }
// some other test ...
    #[test]
    fn validate_team_score_1() {
        let scores = build_scores_table(get_results());
        let team = scores.get("England").unwrap();
        assert_eq!(team.goals_scored, 1); // This line says England scored 1 now
        assert_eq!(team.goals_conceded, 2); // This line says England conceded 2 now
    }

Appendix: This is my complete and solved hashmap3.rs file, i have tweaked the test as shown in the proposed fix:

// A list of scores (one per line) of a soccer match is given. Each line
// is of the form :
// <team_1_name>,<team_2_name>,<team_1_goals>,<team_2_goals>
// Example: England,France,4,2 (England scored 4 goals, France 2).

// You have to build a scores table containing the name of the team, goals
// the team scored, and goals the team conceded. One approach to build
// the scores table is to use a Hashmap. The solution is partially
// written to use a Hashmap, complete it to pass the test.

// Make me pass the tests!

// Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::collections::HashMap;

// A structure to store team name and its goal details.
struct Team {
    name: String,
    goals_scored: u8,
    goals_conceded: u8,
}

fn build_scores_table(results: String) -> HashMap<String, Team> {
    // The name of the team is the key and its associated struct is the value.
    let mut scores: HashMap<String, Team> = HashMap::new();

    for r in results.lines() {
        let v: Vec<&str> = r.split(',').collect();
        let team_1_name = v[0].to_string();
        let team_1_score: u8 = v[2].parse().unwrap();
        let team_2_name = v[1].to_string();
        let team_2_score: u8 = v[3].parse().unwrap();
        // TODO: Populate the scores table with details extracted from the
        // current line. Keep in mind that goals scored by team_1
        // will be the number of goals conceded from team_2, and similarly
        // goals scored by team_2 will be the number of goals conceded by
        // team_1.
        let team1 = Team {
            name: team_1_name, 
            goals_scored: team_1_score, 
            goals_conceded: team_2_score
        };
        let team2 = Team {
            name: team_2_name, 
            goals_scored: team_2_score, 
            goals_conceded: team_1_score
        };
        scores.insert(team1.name.clone(), team1);
        scores.insert(team2.name.clone(), team2);
    }
    scores
}

#[cfg(test)]
mod tests {
    use super::*;

    fn get_results() -> String {
        let results = "".to_string()
            + "England,France,4,2\n"
            + "France,Italy,3,1\n"
            + "Poland,Spain,2,0\n"
            + "Germany,England,2,1\n";
        results
    }

    #[test]
    fn build_scores() {
        let scores = build_scores_table(get_results());

        let mut keys: Vec<&String> = scores.keys().collect();
        keys.sort();
        assert_eq!(
            keys,
            vec!["England", "France", "Germany", "Italy", "Poland", "Spain"]
        );
    }

    #[test]
    fn validate_team_score_1() {
        let scores = build_scores_table(get_results());
        let team = scores.get("England").unwrap();
        assert_eq!(team.goals_scored, 1);
        assert_eq!(team.goals_conceded, 2);
    }

    #[test]
    fn validate_team_score_2() {
        let scores = build_scores_table(get_results());
        let team = scores.get("Spain").unwrap();
        assert_eq!(team.goals_scored, 0);
        assert_eq!(team.goals_conceded, 2);
    }
}

[shadows-withal]

There's another match where England scored 4 and conceded 2. Add that up with the Germany game and you get 5 scored and 4 conceded total. I think your logic doesn't account for that, but the exericse tests are correct in this instance.

[mcheremnov]

@cscherrNT Hi there, have the same problem but I manage to solve it with .and_modify that takes the anonymous function |team| and updates values of scored and conceded values. I place .and_modify between .entry and .or_insert. In that way, before adding value we check if there are already value with the same key. Hope it would help

[plaes]

While solving the rustlings to learn the Language, I think i found a wrongly configured test in exercises/hashmaps/hashmaps3.rs

Appendix: This is my complete and solved hashmap3.rs file, i have tweaked the test as shown in the proposed fix:

[...]

for r in results.lines() {
    let v: Vec<&str> = r.split(',').collect();
    let team_1_name = v[0].to_string();
    let team_1_score: u8 = v[2].parse().unwrap();
    let team_2_name = v[1].to_string();
    let team_2_score: u8 = v[3].parse().unwrap();
    // TODO: Populate the scores table with details extracted from the
    // current line. Keep in mind that goals scored by team_1
    // will be the number of goals conceded from team_2, and similarly
    // goals scored by team_2 will be the number of goals conceded by
    // team_1.
    let team1 = Team {
        name: team_1_name, 
        goals_scored: team_1_score, 
        goals_conceded: team_2_score
    };
    let team2 = Team {
        name: team_2_name, 
        goals_scored: team_2_score, 
        goals_conceded: team_1_score
    };
    scores.insert(team1.name.clone(), team1);
    scores.insert(team2.name.clone(), team2);

@cscherrNT - You are overwriting existing entries in the hashmap when just using .insert(..). That's why you end up with failing tests.

Although, existing tests should also include checks for France as well.

[cscherrNT]

It seems this is not an issue but an oversight on my part. I still think this is confusing but it doesn't seem to be wrong, so i'm closing this issue as not planned for now.