invr 0.2.1

Declarative data validation engine using invariants executed on Polars DataFrames.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

use crate::infrastructure::polars::kind::PolarsKind;
use crate::invariant::Invariant;
use crate::scope::Scope;
use crate::violation::Violation;
use crate::violation::value_object::metric_value::MetricValue;
use polars::prelude::*;

///
/// Builds the Polars expression computing the sum of the
/// target numeric column.
///
/// Scope:
/// - Requires `Scope::Column`
///
/// Behavior:
/// - Casts the column to `Float64`
/// - Computes `sum()` across all rows
/// - Returns a single scalar representing the column sum
///
/// The resulting metric represents the raw sum value and is not
/// validated against bounds at this stage.
pub fn plan(inv: &Invariant<PolarsKind>) -> Option<Expr> {
    let Scope::Column { name } = inv.scope() else {
        return None;
    };

    Some(col(name).cast(DataType::Float64).sum())
}

///
/// Converts the computed sum into a bounded-range violation.
///
/// Required parameters:
/// - `min`: minimum allowed sum (inclusive)
/// - `max`: maximum allowed sum (inclusive)
///
/// Logic:
/// - Reads the computed sum value
/// - Returns a violation if `sum < min` OR `sum > max`
///
/// Produced metric:
/// - `sum` (float)
pub fn map(inv: &Invariant<PolarsKind>, value: AnyValue) -> Option<Violation> {
    let sum = value.try_extract::<f64>().ok()?;
    let min: f64 = inv.require_param("min").ok()?.parse().ok()?;
    let max: f64 = inv.require_param("max").ok()?.parse().ok()?;

    if sum < min || sum > max {
        Some(
            Violation::new(
                inv.id().clone(),
                inv.severity(),
                inv.scope().clone(),
                format!("sum {sum} not in [{min}, {max}]"),
            )
            .with_metric("sum", MetricValue::Float(sum)),
        )
    } else {
        None
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::domain::invariant::value_object::id::InvariantId;
    use crate::infrastructure::polars::kind::PolarsKind;
    use std::collections::BTreeMap;

    fn make_invariant(column: &str, min: f64, max: f64) -> Invariant<PolarsKind> {
        let id = InvariantId::new("sum_between_test").unwrap();
        let mut params = BTreeMap::new();
        params.insert("min".to_string(), min.to_string());
        params.insert("max".to_string(), max.to_string());

        Invariant::new(
            id,
            PolarsKind::SumBetween,
            Scope::Column {
                name: column.to_string(),
            },
        )
        .with_params(params)
    }

    fn df(values: Vec<i32>) -> DataFrame {
        let series = Series::new(PlSmallStr::from("a"), values);
        DataFrame::new_infer_height(vec![series.into()]).unwrap()
    }

    #[test]
    fn test_plan_returns_expr() {
        let inv = make_invariant("a", 0.0, 10.0);
        let expr = plan(&inv);
        assert!(expr.is_some());
    }

    #[test]
    fn test_sum_between_no_violation() {
        let df = df(vec![1, 2, 3]); // sum = 6
        let inv = make_invariant("a", 0.0, 10.0);

        let result = df.lazy().select([plan(&inv).unwrap()]).collect().unwrap();

        let value = result.columns()[0].get(0).unwrap();
        let violation = map(&inv, value);

        assert!(violation.is_none());
    }

    #[test]
    fn test_sum_between_violation_low() {
        let df = df(vec![1, 1, 1]); // sum = 3
        let inv = make_invariant("a", 5.0, 10.0);

        let result = df.lazy().select([plan(&inv).unwrap()]).collect().unwrap();

        let value = result.columns()[0].get(0).unwrap();
        let violation = map(&inv, value);

        assert!(violation.is_some());
    }

    #[test]
    fn test_sum_between_violation_high() {
        let df = df(vec![10, 10, 10]); // sum = 30
        let inv = make_invariant("a", 0.0, 20.0);

        let result = df.lazy().select([plan(&inv).unwrap()]).collect().unwrap();

        let value = result.columns()[0].get(0).unwrap();
        let violation = map(&inv, value);

        assert!(violation.is_some());
    }

    #[test]
    fn test_wrong_scope_returns_none() {
        let id = InvariantId::new("wrong_scope").unwrap();
        let inv = Invariant::new(id, PolarsKind::SumBetween, Scope::Dataset);

        let expr = plan(&inv);
        assert!(expr.is_none());
    }
}