[nextest-runner] ensure that the last "panicked at" message is picked up

Some libraries like proptest produce a lot of "panicked at" messages. Ensure
that only the last one is picked up.

Also switch the color of panics from bold to fail, which highlights them more
clearly in the output.

nextest-runner/src/reporter/displayer.rs

@@ -1481,15 +1481,15 @@ impl<'a> TestReporterImpl<'a> {
                 writer.write_all(&output.buf[..start])?;
                 writer.write_all(RESET_COLOR)?;
 
-                write!(writer, "{}", FmtPrefix(&self.styles.count))?;
+                write!(writer, "{}", FmtPrefix(&self.styles.fail))?;
 
                 // Strip ANSI escapes from this part of the output. It's unlikely there are any, but
                 // strip it just in case.
                 let mut no_color = strip_ansi_escapes::Writer::new(writer);
                 no_color.write_all(&output.buf[start..end])?;
                 let writer = no_color.into_inner()?;
 
-                write!(writer, "{}", FmtSuffix(&self.styles.count))?;
+                write!(writer, "{}", FmtSuffix(&self.styles.fail))?;
 
                 // `end` is guaranteed to be within the bounds of `output.buf`. (It is actually safe
                 // for it to be equal to `output.buf.len()` -- it gets treated as an empty list in

nextest-runner/src/reporter/helpers.rs

@@ -210,7 +210,9 @@ fn heuristic_should_panic(stdout: &[u8]) -> Option<ByteSubslice<'_>> {
 }
 
 fn heuristic_panic_message(stderr: &[u8]) -> Option<ByteSubslice<'_>> {
-    let panicked_at_match = PANICKED_AT_REGEX.find(stderr)?;
+    // Look for the last instance to handle situations like proptest which repeatedly print out
+    // `panicked at ...` messages.
+    let panicked_at_match = PANICKED_AT_REGEX.find_iter(stderr).last()?;
     // If the previous line starts with "Error: ", grab it as well -- it contains the error with
     // result-based test failures.
     let mut start = panicked_at_match.start();
@@ -300,7 +302,7 @@ test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 13 filtered out;
     }
 
     #[test]
-    fn test_heuristic_stack_trace() {
+    fn test_heuristic_panic_message() {
         let tests: &[(&str, &str)] = &[
             (
                 "thread 'main' panicked at 'foo', src/lib.rs:1\n",
@@ -330,7 +332,17 @@ thread 'test_result_failure' panicked at 'assertion failed: `(left == right)`
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 more text at the end, followed by some newlines"#,
             ),
-            // With RUST_BACKTRACE=1
+            // Multiple panics: only the last one should be extracted.
+            (
+                r#"
+thread 'main' panicked at src/lib.rs:1:
+foo
+thread 'main' panicked at src/lib.rs:2:
+bar
+"#,
+                r#"thread 'main' panicked at src/lib.rs:2:
+bar"#,
+            ), // With RUST_BACKTRACE=1
             (
                 r#"
 some initial text