test(js-checkpoint): add test to less exercise

js/tests/less_test.js

@@ -0,0 +1,15 @@
+export const tests = []
+const t = (f) => tests.push(f)
+
+t(() => typeof less === 'function')
+t(() => less.length === 1)
+
+t(() => less(5) === 4)
+t(() => less(1) === 0)
+t(() => less(0) === -1)
+t(() => less(-1) === -2)
+
+const rand = Math.random()
+t(() => less(rand) === rand - 1)
+
+Object.freeze(tests)