Tests: .ai object limit tests check the symbol's limit and derive the mask's

The symbol test now requires a warning and at most the given number of
objects at every limit below what the reader reads. The mask test takes
its limits from the objects the reader reads and finds where the mask
first fits.

crates/eps/src/ai_editing/tests.rs

@@ -941,9 +941,16 @@ fn a_mask_whose_art_passes_the_object_limit_is_left_out() {
         let limited = out.warnings.iter().any(|w| w == writer::OBJECT_LIMIT);
         (String::from_utf8_lossy(&out.program).replace("\r\n", "\n"), limited)
     };
-    let (all, limited) = text(4);
+    let read = crate::import::objects_read(&export_ai_editing(&doc, &opts()).unwrap().program).unwrap();
+    let (all, limited) = text(read);
     assert!(!limited && all.contains("(AI9_Mask)"), "{all}");
-    let (short, limited) = text(2);
+    let has_mask = |max: usize| text(max).0.contains("(AI9_Mask)");
+    let Some(fit) = (0..=read).find(|&max| has_mask(max)) else { panic!("the mask fits with room for {read} objects") };
+    assert!(fit > 2, "the mask needs room beyond the two squares: {fit}");
+    for max in fit..=read {
+        assert!(has_mask(max), "room for {max} of {read}, the mask fits in {fit}");
+    }
+    let (short, limited) = text(fit - 1);
     assert!(limited);
     assert!(!short.contains("(AI9_Mask)") && !short.contains("%_/ArtDictionary :\n%_/Mask"), "{short}");
     assert_eq!(short.matches("\nf\n").count(), 2, "both squares are written: {short}");
@@ -970,6 +977,9 @@ fn a_symbol_definition_is_written_only_with_room_for_its_instance() {
         let text = String::from_utf8_lossy(&out.program).replace("\r\n", "\n");
         let defined = text.contains("%AI14_BeginSymbol");
         assert_eq!(defined, text.contains("/SymbolInstance :"), "room for {max} of {read}: {text}");
+        assert!(out.warnings.iter().any(|w| w == writer::OBJECT_LIMIT), "art is left out with room for {max} of {read} objects");
+        let objects = crate::import::objects_read(&out.program).unwrap();
+        assert!(objects <= max, "{objects} objects read with room for {max}");
     }
 }