Module quality_gate 

Declarative quality gates over a ProfileReport.

A pipeline that wants to stop on a bad extract has to turn a report into a decision. Doing that by hand means re-deciding, at every call site, what an absent metric means, whether a sampled scan can answer a question about the whole source, and which number belongs in the log line. This module makes that decision data: a QualityPolicy states the requirements and QualityPolicy::evaluate returns a GateResult describing what was checked and what happened.

Evaluation never exits the process, prints, or mutates the report.

Verdicts and evidence

The verdict is three-valued, because a decision and the evidence behind it are separate facts. A requirement about the full source cannot be passed by a truncated or sampled scan: nothing was observed that rules the failure out. It can still be failed by one, when the scan witnessed a violation that more scanning cannot retract. So:

• Verdict::Fail — at least one requirement was conclusively violated.
• Verdict::Inconclusive — nothing was violated, and at least one requirement could not be evaluated (a metric was not analyzed, a column was not profiled, the evidence does not reach as far as the requirement).
• Verdict::Pass — every requirement was evaluated and met.

Fail wins over Inconclusive: a witnessed violation is a decision.

Example

use dataprof_runtime::{ProfileReport, QualityPolicy, Verdict};

fn gate(report: &ProfileReport) -> Result<bool, Box<dyn std::error::Error>> {
    let result = QualityPolicy::new()
        .min_quality_score(90.0)
        .max_null_percentage("customer_id", 0.0)
        .max_null_percentage_any(20.0)
        .require_quality()
        .evaluate(report)?;

    if result.verdict != Verdict::Pass {
        for violation in result.violations() {
            eprintln!("{}: {}", violation.code, violation.message);
        }
    }
    Ok(result.passed())
}

Structs

Check

One requirement and what the report said about it.

CheckBounds

The interval a sampled score was decided on.

GateResult

The structured result of evaluating a QualityPolicy.

QualityPolicy

What a report must satisfy.

Enums

CheckCode

Stable identifier for the requirement a check came from.

CheckStatus

What happened to one requirement.

Evidence

Whether the data behind a number covers the whole source.

EvidenceGap

Why the data behind a number falls short of the whole source.

Expectation

The constraint a check applied.

MetricValue

A number a check read, or a threshold it compared against.

NotEvaluated

Why a requirement was not evaluated.

PolicyError

A policy that cannot be evaluated as written.

PolicyScope

What the requirements in a policy are statements about.

RequiredMetric

A metric a policy requires to have been analyzed.

Verdict

The overall outcome of a policy.