Add C string tests

tests/test.rs

@@ -12,6 +12,7 @@ use proc_macro2::{Delimiter, Group, Ident, Span, TokenStream};
 use quote::{format_ident, quote, quote_spanned, TokenStreamExt};
 use std::borrow::Cow;
 use std::collections::BTreeSet;
+use std::ffi::{CStr, CString};
 
 struct X;
 
@@ -232,6 +233,22 @@ fn test_string() {
     assert_eq!(expected, tokens.to_string());
 }
 
+#[test]
+fn test_c_str() {
+    let s = CStr::from_bytes_with_nul(b"\x01 a 'b \" c\0").unwrap();
+    let tokens = quote!(#s);
+    let expected = "c\"\\u{1} a 'b \\\" c\"";
+    assert_eq!(expected, tokens.to_string());
+}
+
+#[test]
+fn test_c_string() {
+    let s = CString::new(&b"\x01 a 'b \" c"[..]).unwrap();
+    let tokens = quote!(#s);
+    let expected = "c\"\\u{1} a 'b \\\" c\"";
+    assert_eq!(expected, tokens.to_string());
+}
+
 #[test]
 fn test_interpolated_literal() {
     macro_rules! m {