diff --git a/src/core/CCByte_buffer.ml b/src/core/CCByte_buffer.ml
index f0460b06..6cf63301 100644
--- a/src/core/CCByte_buffer.ml
+++ b/src/core/CCByte_buffer.ml
@@ -17,6 +17,13 @@ let[@inline] length self = self.sz
 let[@inline] is_empty self = self.sz = 0
 let[@inline] clear self = self.sz <- 0
 
+(*$T
+    (let b = create() in is_empty b)
+    (let b = create ~cap:32 () in is_empty b)
+    (let b = create() in length b = 0)
+    (let b = create ~cap:32 () in length b = 0)
+*)
+
 let grow_cap_ self =
   min Sys.max_string_length
     (let n = capacity self in n + n lsl 1 + 5)
@@ -76,6 +83,9 @@ let[@inline] set self i c =
   if i < 0 || i >= self.sz then invalid_arg "Byte_buf.set";
   unsafe_set self i c
 
+let[@inline] contents self = Bytes.sub_string self.bytes 0 self.sz
+let[@inline] contents_bytes self = Bytes.sub self.bytes 0 self.sz
+
 let[@inline] append_iter self i = i (add_char self)
 let[@inline] append_seq self seq = Seq.iter (add_char self) seq
 
@@ -112,3 +122,106 @@ let to_seq self =
     else Seq.Cons (Bytes.unsafe_get bytes i, s (i+1))
   in
   s 0
+
+(* TODO: unicode operators.*)
+
+(*$inject
+  let test_count = 2_500
+
+  open QCheck
+
+  type op =
+    | Add_char of char
+    | Add_string of string
+    | Get_contents
+    | Get of int
+    | Clear
+
+  let spf = Printf.sprintf
+
+  let str_op = function
+    | Add_char c -> spf "add_char %C" c
+    | Add_string s -> spf "add_string %S" s
+    | Get_contents -> "contents"
+    | Get i -> spf "get %d" i
+    | Clear -> "clear"
+
+  let gen_op size : (_*_) Gen.t =
+    let open Gen in
+    let base = if size>0 then
+        [1, ((0--size) >|= fun x -> Get x, size);
+        ]
+      else []
+    in
+    frequency (base @ [
+        1, return (Get_contents, size);
+        1, return (Clear, 0);
+        3, (printable >|= fun c -> Add_char c, size+1);
+        1, (string_size (0 -- 100) ~gen:printable >|= fun s ->
+            Add_string s, size+String.length s);
+    ])
+
+  let rec gen_l acc sz n =
+    let open Gen in
+    if n=0 then return (List.rev acc)
+    else (
+      gen_op sz >>= fun (op, sz) ->
+      gen_l (op::acc) sz (n-1)
+    )
+
+  let gen : op list Gen.t = Gen.sized (gen_l [] 0)
+
+  let is_valid ops =
+    let rec loop sz = function
+      | [] ->  true
+      | Add_char _ :: tl -> loop (sz+1) tl
+      | Clear :: tl -> loop 0 tl
+      | Add_string s :: tl -> loop (sz+String.length s) tl
+      | Get n :: tl -> n < sz && loop sz tl
+      | Get_contents :: tl -> loop sz tl
+    in loop 0 ops
+
+  let shrink_op = Iter.(function
+    | Get_contents | Clear -> empty
+    | Get n -> Shrink.int n >|= fun n->Get n
+    | Add_char c -> Shrink.char c >|= fun c -> Add_char c
+    | Add_string s -> Shrink.string s >|= fun s -> Add_string s
+    )
+
+  let arb = make gen ~print:(Print.list str_op)
+      ~shrink:Shrink.(filter is_valid @@ list ~shrink:shrink_op)
+
+  exception Nope of string
+  let prop_consistent ops =
+    let buf = Buffer.create 32 in
+    let b = create ~cap:32 () in
+
+    let run_op op =
+      match op with
+      | Get i ->
+        assert (Buffer.length buf = length b);
+        let c1 = Buffer.nth buf i in
+        let c2 = get b i in
+        if c1<>c2 then raise (Nope (spf "c1=%C, c2=%C" c1 c2))
+
+      | Get_contents ->
+        let s1 = Buffer.contents buf in
+        let s2 = contents b in
+        if s1<>s2 then raise (Nope (spf "s1=%S, s2=%S" s1 s2))
+
+      | Add_char c -> Buffer.add_char buf c; add_char b c
+      | Add_string s -> Buffer.add_string buf s; append_string b s
+      | Clear -> Buffer.clear buf; clear b
+
+    in
+
+    assume (is_valid ops);
+    try List.iter run_op ops; true
+    with Nope str ->
+      Test.fail_reportf "consistent ops failed:\n%s" str;
+      false
+*)
+
+(*$Q
+    arb (fun ops -> prop_consistent ops)
+    *)
diff --git a/src/core/CCByte_buffer.mli b/src/core/CCByte_buffer.mli
index 24c30987..fd6a49c8 100644
--- a/src/core/CCByte_buffer.mli
+++ b/src/core/CCByte_buffer.mli
@@ -15,6 +15,9 @@ val create : ?cap:int -> unit -> t
 val length : t -> int
 (** Current length. *)
 
+val is_empty : t -> bool
+(** [is_empty b] is [length b=0] *)
+
 val capacity : t -> int
 (** Current capacity (size of the array returned by {!bytes}) *)
 
@@ -56,6 +59,12 @@ val set : t -> int -> char -> unit
 
 val unsafe_set : t -> int -> char -> unit
 
+val contents : t -> string
+(** Copy the internal data to a string *)
+
+val contents_bytes : t -> bytes
+(** Copy the internal data to a byte buffer *)
+
 val iter : (char -> unit) -> t -> unit
 
 val fold_left : ('a -> char -> 'a) -> 'a -> t -> 'a