test: improve assertions in bug hunt reproductions

Refine assertions in reproduction tests to be more specific and ensure they
correctly validate expected error messages and warnings.

This includes improvements to:
- duplicate_csv_headers_not_silent
- repeated_import_coordinates_not_silently_overwritten
- long_csv_row_is_not_silently_dropped
- wide_cell_clamps_without_overflow

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/gemma-4-26B-A4B-it-qat-GGUF:UD-Q4_K_XL)

tests/bug_hunt_reproductions.rs

@@ -58,7 +58,12 @@ fn csv_nonfinite_is_not_zero() {
 fn duplicate_csv_headers_not_silent() {
     let result = parse_csv_bytes_with_warnings(b"A,A\n1,2\n");
     assert!(
-        result.is_err() || !result.unwrap().1.is_empty(),
+        match result {
+            Err(error) => error.to_string().to_lowercase().contains("duplicate"),
+            Ok((_, warnings)) => warnings.iter().any(|warning| {
+                warning.to_lowercase().contains("duplicate") && warning.contains("A")
+            }),
+        },
         "duplicate headers silently overwrite a field"
     );
 }
@@ -88,7 +93,13 @@ fn repeated_import_coordinates_not_silently_overwritten() {
         .filter_map(|(_, v)| v.as_f64())
         .sum();
     assert!(
-        total == 30.0 || !warnings.is_empty(),
+        total == 30.0
+            || warnings.iter().any(|warning| {
+                let warning = warning.to_lowercase();
+                (warning.contains("duplicate") || warning.contains("overwrite"))
+                    && warning.contains("east")
+                    && warning.contains("revenue")
+            }),
         "total {total}, no warning {warnings:?}"
     );
 }
@@ -159,10 +170,24 @@ fn label_stays_off_axes_in_new_view() {
 fn long_csv_row_is_not_silently_dropped() {
     let r = parse_csv_bytes_with_warnings(b"A,B\n1,2,3\n");
     assert!(
-        r.is_err() || !r.unwrap().1.is_empty(),
+        match r {
+            Err(error) => {
+                let message = error.to_string().to_lowercase();
+                message.contains("3")
+                    && message.contains("2")
+                    && (message.contains("field") || message.contains("column"))
+            }
+            Ok((_, warnings)) => warnings.iter().any(|warning| {
+                let warning = warning.to_lowercase();
+                warning.contains("3")
+                    && warning.contains("2")
+                    && (warning.contains("field") || warning.contains("column"))
+            }),
+        },
         "extra value 3 dropped silently"
     );
 }
+// Passing control: embedded carriage returns already survive persistence.
 #[test]
 fn literal_cr_name_survives_roundtrip() {
     let mut w = Workbook::new("test");
@@ -357,7 +382,11 @@ fn wide_cell_clamps_without_overflow() {
         false,
         0,
     );
-    assert!(widths.iter().all(|w| *w <= 32));
+    assert_eq!(
+        widths,
+        vec![improvise::ui::viewport::MAX_COL_WIDTH],
+        "the Revenue column must reach the width cap"
+    );
 }
 #[test]
 fn ordinary_controls() {