backhopper-core 0.37.0

// Copyright (C) 2026 Michael S. Klishin and Contributors
// SPDX-License-Identifier: Apache-2.0 OR MIT
// See LICENSE-APACHE and LICENSE-MIT for details.

use std::path::PathBuf;

use backhopper_core::compat::patch::{EvaluationContext, EvaluationFiles, Patch};
use backhopper_core::compat::scope::PinScope;
use backhopper_core::model::names::{ProjectName, TagName};
use backhopper_core::model::pin::Pin;
use backhopper_core::model::snapshot::{Snapshot, state};
use backhopper_core::model::verdict::{Reason, SeriesVerdict};
use backhopper_test_support::{canonical_snapshot, module_with, snapshot_header};

const ORIGINAL: &str = "-module(demo).\n-export([greet/1]).\ngreet(Name) -> Name.\n";
const PATCH: &str = "\
diff --git a/src/demo.erl b/src/demo.erl
--- a/src/demo.erl
+++ b/src/demo.erl
@@ -1,3 +1,4 @@
 -module(demo).
 -export([greet/1]).
+example() -> demo:greet(<<\"x\">>).
 greet(Name) -> Name.
";

fn snapshot() -> Snapshot<state::Canonical> {
    canonical_snapshot(
        snapshot_header("demo", "v1.0.0"),
        vec![module_with("demo", &[("greet", 1)])],
    )
}

fn pin() -> Pin {
    Pin::new(
        ProjectName::new("demo").unwrap(),
        TagName::new("v1.0.0").unwrap(),
    )
}

fn evaluate(snap: Snapshot<state::Canonical>, files: EvaluationFiles) -> SeriesVerdict {
    let scope = PinScope::from_snapshot(pin().project.clone(), &snap, Vec::new());
    let ctx = EvaluationContext::for_pin(pin(), snap)
        .with_scope(scope)
        .with_files(files);
    Patch::parse(PATCH.as_bytes())
        .unwrap()
        .analyze()
        .evaluate_series(&[ctx])
        .verdict
}

#[test]
fn file_absent_when_path_missing_at_pin() {
    // a snapshot without the demo module: a missing demo.erl is a genuine FileAbsent, not a relocation
    let empty_snap = canonical_snapshot(snapshot_header("demo", "v1.0.0"), vec![]);
    let files = EvaluationFiles::new().with(PathBuf::from("src/demo.erl"), None);
    let series = evaluate(empty_snap, files);
    let r0 = &series.results[0];
    assert!(
        r0.verdict
            .reasons()
            .iter()
            .any(|r| matches!(r, Reason::FileAbsent { path } if path.ends_with("demo.erl")))
    );
}

#[test]
fn no_drift_when_context_matches() {
    let files = EvaluationFiles::new().with(
        PathBuf::from("src/demo.erl"),
        Some(ORIGINAL.as_bytes().to_vec()),
    );
    let series = evaluate(snapshot(), files);
    let r0 = &series.results[0];
    assert!(
        !r0.verdict
            .reasons()
            .iter()
            .any(|r| matches!(r, Reason::ContextDrift { .. }))
    );
}

#[test]
fn preimage_missing_reported_when_target_diverges() {
    let drifted = "-module(demo).\n-export([greet/2]).\ngreet(Name, _) -> Name.\n";
    let files = EvaluationFiles::new().with(
        PathBuf::from("src/demo.erl"),
        Some(drifted.as_bytes().to_vec()),
    );
    let series = evaluate(snapshot(), files);
    let r0 = &series.results[0];
    assert!(
        r0.verdict
            .reasons()
            .iter()
            .any(|r| matches!(r, Reason::PreimageMissing { hunk_index: 0, .. }))
    );
}

#[test]
fn pin_files_unset_for_path_yields_no_file_check() {
    let files = EvaluationFiles::new();
    let series = evaluate(snapshot(), files);
    let r0 = &series.results[0];
    assert!(
        !r0.verdict
            .reasons()
            .iter()
            .any(|r| matches!(r, Reason::FileAbsent { .. } | Reason::ContextDrift { .. }))
    );
}