chore(fmt): Add debug impls

src/fmt/mod.rs

@@ -158,7 +158,11 @@ impl Write for Formatter {
 
 impl fmt::Debug for Formatter {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("Formatter").finish()
+        let buf = self.buf.borrow();
+        f.debug_struct("Formatter")
+            .field("buf", &buf)
+            .field("write_style", &self.write_style)
+            .finish()
     }
 }
 

src/fmt/writer/buffer.rs

@@ -2,6 +2,7 @@ use std::{io, sync::Mutex};
 
 use crate::fmt::writer::WriteStyle;
 
+#[derive(Debug)]
 pub(in crate::fmt::writer) struct BufferWriter {
     target: WritableTarget,
     write_style: WriteStyle,
@@ -129,6 +130,12 @@ impl Buffer {
     }
 }
 
+impl std::fmt::Debug for Buffer {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        String::from_utf8_lossy(self.as_bytes()).fmt(f)
+    }
+}
+
 /// Log target, either `stdout`, `stderr` or a custom pipe.
 ///
 /// Same as `Target`, except the pipe is wrapped in a mutex for interior mutability.

src/fmt/writer/mod.rs

@@ -2,7 +2,7 @@ mod buffer;
 mod target;
 
 use self::buffer::BufferWriter;
-use std::{fmt, io, mem, sync::Mutex};
+use std::{io, mem, sync::Mutex};
 
 pub(super) use self::buffer::Buffer;
 
@@ -44,6 +44,7 @@ impl From<WriteStyle> for anstream::ColorChoice {
 }
 
 /// A terminal target with color awareness.
+#[derive(Debug)]
 pub(crate) struct Writer {
     inner: BufferWriter,
 }
@@ -62,12 +63,6 @@ impl Writer {
     }
 }
 
-impl fmt::Debug for Writer {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("Writer").finish()
-    }
-}
-
 /// A builder for a terminal writer.
 ///
 /// The target and style choice can be configured before building.