Defmt impl for String

src/defmt.rs

@@ -1,18 +1,29 @@
 //! Defmt implementations for heapless types
 //!
 
-use defmt::Formatter;
-use generic_array::ArrayLength;
-
+use crate::ArrayLength;
 use crate::Vec;
+use defmt::Formatter;
 
 impl<T, N> defmt::Format for Vec<T, N>
-    where N: ArrayLength<T>, T: defmt::Format {
+where
+    N: ArrayLength<T>,
+    T: defmt::Format,
+{
     fn format(&self, fmt: &mut Formatter) {
         fmt.fmt_slice(self)
     }
 }
 
+impl<N> defmt::Format for crate::String<N>
+where
+    N: ArrayLength<u8>,
+    u8: defmt::Format,
+{
+    fn format(&self, fmt: &mut Formatter) {
+        fmt.str(self.as_str());
+    }
+}
 
 #[cfg(test)]
 mod tests {
@@ -23,7 +34,7 @@ mod tests {
     #[test]
     /// Tests encoding Vec with defmt,
     /// based loosely on https://github.com/knurling-rs/defmt/blob/main/tests/encode.rs#L483
-    fn test_defmt_format() {
+    fn test_defmt_format_vec() {
         let v: Vec<_, U8> = Vec::from_slice(b"abc").unwrap();
         let index = defmt::export::fetch_string_index();
 
@@ -33,15 +44,43 @@ mod tests {
         let timestamp = defmt::export::fetch_timestamp();
         let mut formatter = defmt::Formatter::new();
         defmt::winfo!(formatter, "{:?}", v);
-        assert_eq!(formatter.bytes(), &[
-            index,
-            timestamp,
-            v.len().try_into().unwrap(),
-            fake_interned,  // Faked
-            // Data bytes.
-            97u8,
-            98u8,
-            99u8,
-        ]);
+        assert_eq!(
+            formatter.bytes(),
+            &[
+                index,
+                timestamp,
+                v.len().try_into().unwrap(),
+                fake_interned, // Faked
+                // Data bytes.
+                97u8,
+                98u8,
+                99u8,
+            ]
+        );
+    }
+
+    /// Tests encoding String with defmt,
+    /// based loosely on https://github.com/knurling-rs/defmt/blob/main/tests/encode.rs#L483
+    #[test]
+    fn test_defmt_format_str() {
+        let mut v: crate::String<crate::consts::U32> = crate::String::new();
+        v.push_str("foo").unwrap();
+        let index = defmt::export::fetch_string_index();
+
+        let timestamp = defmt::export::fetch_timestamp();
+        let mut formatter = defmt::Formatter::new();
+        defmt::winfo!(formatter, "{:?}", v);
+        assert_eq!(
+            formatter.bytes(),
+            &[
+                index,
+                timestamp,
+                v.len().try_into().unwrap(),
+                // Data bytes.
+                102u8,
+                111u8,
+                111u8,
+            ]
+        );
     }
 }