refactor(engine): move tests_*.rs to tests/<topic>.rs

crates/engine/src/tests/transparencygrid.rs

@@ -0,0 +1,28 @@
+//! View → Show Transparency Grid is engine view state of each open document (M3.88).
+
+use serde_json::json;
+
+use crate::*;
+
+#[test]
+fn transparency_grid_is_per_document_view_state() {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({})).unwrap();
+    let grid = |s: &Session| s.doc().unwrap().transparency_grid;
+    assert!(!grid(&s));
+    assert_eq!(s.execute("view.transparencyGrid", &json!({})).unwrap(), json!({"on": true}));
+    assert!(grid(&s));
+    // Not an edit: nothing to undo, the document stays clean, the journal skips it.
+    let st = s.doc().unwrap();
+    assert!(st.history.undo.is_empty() && !st.is_dirty());
+    // Another document has its own setting.
+    s.execute("file.new", &json!({})).unwrap();
+    assert!(!grid(&s));
+    assert_eq!(s.execute("view.transparencyGrid", &json!({"on": false})).unwrap(), json!({"on": false}));
+    s.execute("document.activate", &json!({"index": 0})).unwrap();
+    assert!(grid(&s));
+    assert_eq!(s.execute("view.transparencyGrid", &json!({})).unwrap(), json!({"on": false}));
+    assert_eq!(s.execute("view.transparencyGrid", &json!({"on": true})).unwrap(), json!({"on": true}));
+    s.execute("document.activate", &json!({"index": 1})).unwrap();
+    assert!(!grid(&s));
+}