Test: a DWG keeps an OLE2FRAME's data and frame corners (#2422)

The DWG object has no corner fields; the position travels in the start of the OLE
data, which the bridge keeps. The test builds that header with known corners and
checks them at 2000, 2010 and 2018.

crates/io/tests/it/ole_frame.rs

@@ -1,15 +1,40 @@
-//! An OLE2FRAME is kept as an unknown entity; a DWG save carries it with its data (#2422).
+//! An OLE2FRAME is kept as an unknown entity; a DWG save carries it with its data and frame
+//! position (#2422). A DWG's OLE2FRAME object has no corner fields: the position travels in the
+//! start of the OLE data (a 2-byte marker, then the frame's four corners as three little-endian
+//! doubles each: upper left, upper right, lower right, lower left), which is how the DXF's
+//! groups 10 and 11 come back. That layout is read from the acadrust dependency's decoder.
 
 use cadcraft_doc::EntityKind;
 use cadcraft_io::{SaveOptions, Version, read, read_dxf, write_with};
 
+const UL: (f64, f64) = (30.14, -18.99);
+const LR: (f64, f64) = (35.27, -22.39);
+
+/// The OLE data: the envelope with the frame's corners.
+fn blob() -> Vec<u8> {
+    let mut b = vec![1u8, 0];
+    for (x, y) in [UL, (LR.0, UL.1), LR, (UL.0, LR.1)] {
+        for v in [x, y, 0.0] {
+            b.extend_from_slice(&v.to_le_bytes());
+        }
+    }
+    b
+}
+
 /// A 2000 DXF with one OLE2FRAME: corners, the binary data and the end marker (DXF Reference).
 fn dxf() -> String {
-    String::from(
+    let data = blob();
+    let hex: String = data.iter().map(|b| format!("{b:02X}")).collect();
+    format!(
         "0\nSECTION\n2\nHEADER\n9\n$ACADVER\n1\nAC1015\n0\nENDSEC\n0\nSECTION\n2\nENTITIES\n\
          0\nOLE2FRAME\n5\n2B\n100\nAcDbEntity\n8\n0\n100\nAcDbOle2Frame\n70\n2\n3\nOLE Object\n\
-         10\n30.14\n20\n-18.99\n30\n0\n11\n35.27\n21\n-22.39\n31\n0\n71\n2\n72\n0\n90\n8\n310\n0102030405060708\n1\nOLE\n\
+         10\n{}\n20\n{}\n30\n0\n11\n{}\n21\n{}\n31\n0\n71\n2\n72\n0\n90\n{}\n310\n{hex}\n1\nOLE\n\
          0\nENDSEC\n0\nEOF\n",
+        UL.0,
+        UL.1,
+        LR.0,
+        LR.1,
+        data.len()
     )
 }
 
@@ -21,16 +46,17 @@ fn ole(d: &cadcraft_doc::Drawing) -> Option<cadcraft_doc::Unknown> {
 }
 
 #[test]
-fn a_dwg_keeps_an_ole_frame_with_its_data() {
+fn a_dwg_keeps_an_ole_frame_with_its_data_and_position() {
     let d = read_dxf(dxf().as_bytes()).unwrap();
     assert!(ole(&d).is_some());
+    let want: String = blob().iter().map(|b| format!("{b:02X}")).collect();
     for v in [Version::R2000, Version::R2010, Version::R2018] {
         let dwg = write_with(&d, "x.dwg", &SaveOptions { version: Some(v), binary: false }).unwrap();
         let back = read(&dwg, "x.dwg").unwrap();
         let u = ole(&back).unwrap_or_else(|| panic!("{v:?}: the OLE2FRAME is gone"));
         let data: String = u.tags.iter().filter(|t| t.code == 310).map(|t| t.value.to_ascii_uppercase()).collect();
-        assert_eq!(data, "0102030405060708", "{v:?}: data");
-        // Only the data is compared: with this stand-in blob the DWG round trip returns default
-        // corners (1,1)/(0,0), which a real object might not do; not verified without a real file.
+        let corner = |code: i32| u.tags.iter().find(|t| t.code == code).and_then(|t| t.value.trim().parse::<f64>().ok());
+        assert_eq!(data, want, "{v:?}: data");
+        assert_eq!((corner(10), corner(20), corner(11), corner(21)), (Some(UL.0), Some(UL.1), Some(LR.0), Some(LR.1)), "{v:?}: frame corners");
     }
 }