Add tests for when-some, plus one for when-let.

when-some and when-let behave very similarly. This adds the opposite
case of one of these tests to when-let.

Author: alysbrooks

test/clojure/core_test/when_let.cljc

@@ -11,6 +11,8 @@
                      (is (nil? (when-let [x nil] x))))
                    (testing "basic single-binding tests using seqs"
                      (is (= '(0 1 2 3 4) (when-let [x (range 5)] x))))
+                   (testing "unlike, when-some, we're looking for not-nil specifically, so false evaluates"
+                     (is (nil? (when-let [x false] x))))
                    (testing "seq is only called once"
                      (let [calls (atom 0)
                            seq-fn (fn s [] (lazy-seq

test/clojure/core_test/when_some.cljc

@@ -0,0 +1,28 @@
+
+(ns clojure.core-test.when-some
+  (:require [clojure.test :as t :refer [deftest is testing]]
+            [clojure.core-test.portability #?(:cljs :refer-macros :default :refer) [when-var-exists]]))
+
+(when-var-exists when-some
+  (deftest test-when-some
+    (testing "basic single-binding tests using vectors or nil"
+      (is (= [0 1 2 3 4] (when-some [x [0 1 2 3 4] ] x)))
+      (is (not (nil? (when-some [x [nil]] x))))
+      (is (= [] (when-some [x []] x)))
+      (is (nil? (when-some [x nil] x))))
+    (testing "basic single-binding tests using seqs"
+      (is (= '(0 1 2 3 4) (when-some [x (range 5)] x))))
+    (testing "unlike when-let, we're looking for not-nil specifically, so false evaluates"
+      (is (= false (when-some [x false] x))))
+    (testing "seq is only called once"
+      (let [calls (atom 0)
+            seq-fn (fn s [] (lazy-seq
+                              (swap! calls inc)
+                              (cons 1 (s))))
+            s (take 5 (seq-fn))]
+        (is (= '(1 1 1 1 1) (when-some [x s] x)))
+        (is (= @calls 5))))
+    (testing "without a body, truth doesn't matter"
+      (is (nil? (when-some [x nil])))
+      (is (nil? (when-some [x [false]])))
+      (is (nil? (when-some [x [true]]))))))