Merge remote-tracking branch 'Mododo/bitstring_tail'

src/util.rs

@@ -220,10 +220,11 @@ impl std::fmt::Display for Bitstring<'_> {
 
         if let Some(mut last_byte) = last_byte {
             let tag = if rem % 4 != 0 { "_" } else { "" };
-            if rem <= 4 {
+            let rem = 1 + (rem >> 2) as usize;
+            if rem == 1 {
                 last_byte >>= 4;
             }
-            ok!(write!(f, "{last_byte:x}{tag}"));
+            ok!(write!(f, "{last_byte:0rem$x}{tag}"));
         }
 
         Ok(())
@@ -290,3 +291,52 @@ pub(crate) fn debug_struct_field2_finish(
     builder.field(name2, value2);
     builder.finish()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn bitstring_zero_char_with_completion_tag() {
+        assert_eq!(
+            format!(
+                "{}",
+                Bitstring {
+                    bytes: &[0b_0100_0000],
+                    bit_len: 2
+                }
+            ),
+            format!("{:x}_", 0b_0110)
+        );
+        assert_eq!(
+            format!(
+                "{}",
+                Bitstring {
+                    bytes: &[0b_0000_1000],
+                    bit_len: 5
+                }
+            ),
+            format!("{:x}{:x}_", 0b_0000, 0b_1100)
+        );
+        assert_eq!(
+            format!(
+                "{}",
+                Bitstring {
+                    bytes: &[0b_0000_1000, 0b_0100_0000],
+                    bit_len: 8 + 2
+                }
+            ),
+            format!("{:x}{:x}{:x}_", 0b_0000, 0b_1000, 0b_0110)
+        );
+        assert_eq!(
+            format!(
+                "{}",
+                Bitstring {
+                    bytes: &[0b_0100_0000, 0b_0000_1000],
+                    bit_len: 8 + 5
+                }
+            ),
+            format!("{:x}{:x}{:x}{:x}_", 0b_0100, 0b_0000, 0b_0000, 0b_1100)
+        );
+    }
+}