diff --git a/src/data/CCImmutArray.ml b/src/data/CCImmutArray.ml
index fca18714..f69e32e0 100644
--- a/src/data/CCImmutArray.ml
+++ b/src/data/CCImmutArray.ml
@@ -3,9 +3,11 @@
 
 (** {1 Immutable Arrays} *)
 
-(* TODO: tests *)
 (* TODO: transient API? for batch modifications *)
 
+(*$inject let print_array f a = to_list a |> Array.of_list |> Q.Print.(array f)
+*)
+
 type 'a t = 'a array
 
 let empty = [| |]
@@ -27,6 +29,11 @@ let set a n x =
   a'.(n) <- x;
   a'
 
+(*$= set & ~printer:(print_array Q.Print.int)
+  (of_list [0]) (set (of_list [5]) 0 0)
+  (of_list [1; 3; 4; 5]) (set (of_list [1; 2; 4; 5]) 1 3)
+*)
+
 let sub = Array.sub (* Would this not be better implemented with CCArray_slice *)
 
 let map = Array.map
@@ -38,6 +45,13 @@ let append a b =
   Array.init (na + length b)
     (fun i -> if i < na then a.(i) else b.(i-na))
 
+(*$= append & ~printer:(print_array Q.Print.int)
+  empty (append empty empty)
+  (of_list [1; 2; 3]) (append empty (of_list [1; 2; 3]))
+  (of_list [1; 2; 3]) (append (of_list [1; 2; 3]) empty)
+  (of_list [3; 1; 4; 1; 5]) (append (of_list [3; 1]) (of_list [4; 1; 5]))
+*)
+
 let iter = Array.iter
 
 let iteri = Array.iteri
@@ -53,6 +67,10 @@ let foldi f acc a =
        acc)
     acc a
 
+(*$= foldi & ~printer:Q.Print.(list (pair int string))
+  ([2, "baz"; 1, "bar"; 0, "foo"]) (foldi (fun l i a -> (i, a) :: l) [] (of_list ["foo"; "bar"; "baz"]))
+*)
+
 exception ExitNow
 
 let for_all p a =
@@ -61,12 +79,37 @@ let for_all p a =
     true
   with ExitNow -> false
 
+(*$= for_all & ~printer:Q.Print.bool
+  true (for_all (fun _ -> false) empty)
+  false (for_all (fun _ -> false) (singleton 3))
+  true (for_all (fun n -> n mod 2 = 0) (of_list [2; 4; 8]))
+  false (for_all (fun n -> n mod 2 = 0) (of_list [2; 4; 5; 8]))
+*)
+
 let exists p a =
   try
     Array.iter (fun x -> if p x then raise ExitNow) a;
     false
   with ExitNow -> true
 
+(*$= exists & ~printer:Q.Print.bool
+  false (exists (fun _ -> true) empty)
+  true (exists (fun _ -> true) (singleton 3))
+  false (exists (fun _ -> false) (singleton 3))
+  false (exists (fun n -> n mod 2 = 1) (of_list [2; 4; 8]))
+  true (exists (fun n -> n mod 2 = 1) (of_list [2; 4; 5; 8]))
+*)
+
+(*$Q
+  Q.(list bool) (fun l -> let a = of_list l in not @@ exists (fun b -> b) a = for_all not a)
+  Q.(list bool) (fun l -> let a = of_list l in not @@ for_all (fun b -> b) a = exists not a)
+*)
+
+(*$Q
+ Q.(list bool) (fun l -> exists (fun b -> b) (of_list l) = List.fold_left (||) false l)
+ Q.(list bool) (fun l -> for_all (fun b -> b) (of_list l) = List.fold_left (&&) true l)
+ *)
+
 (** {2 Conversions} *)
 
 type 'a iter = ('a -> unit) -> unit