Test for defining protocol on potentially infinite data structures

test/babashka/protocols_test.clj

@@ -0,0 +1,39 @@
+(ns babashka.protocols-test
+  (:require  [babashka.test-utils :refer [bb]]
+             [clojure.test :as t :refer [deftest is]]))
+
+(deftest safe-datafy
+  (is (bb
+       "
+(ns safe-datafy
+  (:require [clojure.core.protocols :as p]
+            [clojure.datafy :as df]))
+
+(def max-sequence-length 100000)
+
+(defn infinite-sequence-chunking [s]
+  (cond-> (take max-sequence-length s)
+    (< max-sequence-length (bounded-count (inc max-sequence-length) s))
+    (vary-meta merge (meta s) {:nextjournal.seq/truncated? true})))
+
+(extend-protocol p/Datafiable
+  clojure.lang.LazySeq
+  (df/datafy [s] (infinite-sequence-chunking s))
+  clojure.lang.Iterate
+  (df/datafy [s] (infinite-sequence-chunking s))
+  clojure.lang.Repeat
+  (df/datafy [s] (infinite-sequence-chunking s))
+  clojure.lang.Cycle
+  (df/datafy [s] (infinite-sequence-chunking s)))
+
+(defn safe-datafy [x]
+  (let [dtf (cond-> x
+              (not (instance? clojure.lang.IRef x))
+              df/datafy)]
+    (cond-> dtf
+      (instance? clojure.lang.IObj dtf)
+      (vary-meta (fn [m] (merge (dissoc m :clojure.datafy/class :clojure.datafy/obj)
+                                (meta x)))))))
+
+[(safe-datafy (range))
+ (safe-datafy (repeat 1))]")))