From 6e1e600ec8b3f23d1a78b44093e0b20f9c6c78c8 Mon Sep 17 00:00:00 2001
From: Miguel de Benito Delgado <m.debenito.d@gmail.com>
Date: Sat, 21 Jun 2025 21:11:39 +0200
Subject: [PATCH] Add operators start-with and end-with

---
 src/beicon/v2/core.cljs        | 16 ++++++++++++++++
 src/beicon/v2/operators.cljs   | 12 ++++++++++++
 test/beicon/tests/v2_test.cljs | 18 ++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/src/beicon/v2/core.cljs b/src/beicon/v2/core.cljs
index 2c84f4f..c186fa0 100644
--- a/src/beicon/v2/core.cljs
+++ b/src/beicon/v2/core.cljs
@@ -421,6 +421,22 @@
   [ob]
   (ops/pipe (ops/merge-all 1) ob))
 
+(defn start-with
+  "Emits the provided value(s) before any other emissions
+   from the source Observable."
+  [& args]
+  (let [values (butlast args)
+        ob     (c/last args)]
+    (ops/pipe (apply ops/start-with values) ob)))
+
+(defn end-with
+  "Emits the provided value(s) after all other emissions
+   from the source Observable."
+  [& args]
+  (let [values (butlast args)
+        ob     (c/last args)]
+    (ops/pipe (apply ops/end-with values) ob)))
+
 (defn skip
   "Bypasses a specified number of elements in an
   observable sequence and then returns the remaining
diff --git a/src/beicon/v2/operators.cljs b/src/beicon/v2/operators.cljs
index 7d3b6d5..0645399 100644
--- a/src/beicon/v2/operators.cljs
+++ b/src/beicon/v2/operators.cljs
@@ -78,6 +78,18 @@
   [f]
   (rx/concatMap #(f %2 %1)))
 
+(def ^function start-with
+  "Returns an observable sequence that upon subscription emits the
+   specified values before it begins to emit the elements of the
+   source observable sequence."
+  rx/startWith)
+
+(def ^function end-with
+  "Returns an observable sequence that emits the elements of the
+   source observable and then emits the specified values after the
+   source completes."
+  rx/endWith)
+
 (def ^function skip
   "Bypasses a specified number of elements in an
   observable sequence and then returns the remaining
diff --git a/test/beicon/tests/v2_test.cljs b/test/beicon/tests/v2_test.cljs
index d639f1f..204f26c 100644
--- a/test/beicon/tests/v2_test.cljs
+++ b/test/beicon/tests/v2_test.cljs
@@ -216,6 +216,24 @@
       (drain! sample #(t/is (= % [2 3 4 5])))
       (rx/on-end sample done))))
 
+(t/deftest observable-start-with
+  (t/async done
+    (let [nums (rx/from [1 2 3])
+          s (rx/start-with 0 nums)
+          u (rx/start-with -2 -1 s)]
+      (t/is (rx/observable? u))
+      (drain! u #(t/is (= % [-2 -1 0 1 2 3])))
+      (rx/on-end u done))))
+
+(t/deftest observable-end-with
+  (t/async done
+    (let [nums (rx/from [1 2 3])
+          s (rx/end-with 4 (rx/from nums))
+          u (rx/end-with 5 6 (rx/from s))]
+      (t/is (rx/observable? u))
+      (drain! u #(t/is (= % [1 2 3 4 5 6])))
+      (rx/on-end u done))))
+
 (t/deftest subject-as-ideref
   (t/async done
     (let [nums (rx/from [1 1 1 2 3 4 5])