test(script): per-key methods in another comp leave both key selections alone (#1531)

The worse half of #1531: when the property's comp remembers a key the user
selected, the old code didn't just do nothing, it eased, held or removed
that selected key instead of the one named. This test, written by
@switch87 in #1558, pins it: only the named keys change, removeKey(1)
removes key 1, the active comp stays active with its own key selection,
and the other comp's remembered selection comes back as it was. It fails
on the code before #1558 and passes on main.

crates/script/src/tests.rs

@@ -1326,6 +1326,50 @@ fn key_interpolation_and_ease_apply_outside_the_active_comp() {
     assert!(v[3].as_f64().is_some_and(|x| (x - -44.5).abs() > 1.0), "{v}");
 }
 
+/// #1531: a key the user selected in the property's comp stays selected, and only the named key
+/// changes (on the old code the change went to the selected key instead).
+/// The active comp's own key selection is untouched.
+#[test]
+fn a_per_key_method_in_another_comp_changes_only_its_key_and_keeps_both_selections() {
+    let mut s = session();
+    let o = ok(
+        &mut s,
+        r#"
+        var C = app.project.items.addComp('C', 100, 100, 1, 10, 20);
+        var p = C.layers.addNull().transform.rotation;
+        p.setValuesAtTimes([0, 1, 2], [0, 90, 180]);
+        var A = app.project.items.addComp('A', 100, 100, 1, 10, 20);
+        A.openInViewer();
+        var q = A.layers.addNull().transform.opacity;
+        q.setValuesAtTimes([0, 1], [0, 100]);
+        app.run('edit.deselectAll', {});
+        q.setSelectedAtKey(2, true);
+        // the user selected key 3 of C earlier: C remembers it while A is active
+        p.setSelectedAtKey(3, true);
+        p.setInterpolationTypeAtKey(1, KeyframeInterpolationType.HOLD);
+        p.setTemporalEaseAtKey(2, [new KeyframeEase(0, 80)]);
+        var hold = KeyframeInterpolationType.HOLD;
+        var out = [p.keyOutInterpolationType(1) == hold, p.keyOutInterpolationType(3) == hold, p.keyInInterpolationType(3) == hold,
+          p.keyInTemporalEase(2)[0].influence, p.keyInTemporalEase(3)[0].influence,
+          q.keySelected(1), q.keySelected(2)];
+        p.removeKey(1);
+        out.push(p.numKeys, p.keyTime(1), p.keyValue(1), q.keySelected(2), app.project.activeItem.name);
+        // C's remembered selection is live again once C is active: still the user's key (now 2)
+        C.openInViewer();
+        out.push(p.keySelected(1), p.keySelected(2));
+        out;
+        "#,
+    );
+    let v = o.result.as_array().unwrap();
+    let ease = |i: usize| v[i].as_f64().unwrap();
+    assert_eq!(&v[..3], &[json!(true), json!(false), json!(false)], "only key 1 holds: {v:?}");
+    assert!((ease(3) - 80.0).abs() < 1e-6, "key 2 eased: {v:?}");
+    assert!((ease(4) - 80.0).abs() > 1e-6, "key 3 untouched: {v:?}");
+    assert_eq!(&v[5..7], &[json!(false), json!(true)], "A's key selection kept: {v:?}");
+    assert_eq!(&v[7..12], &[json!(2), json!(1), json!(90), json!(true), json!("A")], "key 1 removed, A still active: {v:?}");
+    assert_eq!(&v[12..], &[json!(false), json!(true)], "C's key selection kept, the target key not added: {v:?}");
+}
+
 /// #808: sourcePointToComp and compPointToSource follow the layer's transform.
 #[test]
 fn source_point_conversions_follow_the_layer_transform() {