Minimal reproduction for whitespace being deleted with --verus-only

Author: Raphael Sofaer

tests/verus-only-does-not-touch-rust.rs

@@ -0,0 +1,17 @@
+#[test]
+fn verus_only_extra_line() {
+    let file = r"
+// The newline below this comment is deleted with --verus-only.
+
+use std::marker::PhantomData;
+
+pub fn main(){ } // Formatting error here pops up without --verus-only
+";
+    let mut config = verusfmt::RunOptions::default();
+    // Currently the only effect of the verus-only command line argument
+    // is to set config.run_rustfmt to false, so use that.
+    config.run_rustfmt = false;
+    let formatted = verusfmt::run(file, config).unwrap();
+    assert_eq!(formatted, file);
+
+}