propagators/switcher.test

Author: xieyuheng

TODO.md

@@ -2,8 +2,6 @@
 
 > https://github.com/cicada-lang/propagator/issues/4
 
-propagators/switcher.test
-
 propagators/boolean -- inverter
 
 propagators/conditional

src/propagators/switcher.test.ts

@@ -0,0 +1,25 @@
+import assert from "node:assert"
+import test from "node:test"
+import { Belief, isBelief } from "../belief/Belief.js"
+import { beliefEqual } from "../belief/beliefEqual.js"
+import { patch } from "../cell/index.js"
+import { nothing } from "../nothing/index.js"
+import { run } from "../scheduler/index.js"
+import { switcher } from "./switcher.js"
+
+test("propagators / switcher", async () => {
+  const [control, input, output] = switcher()
+  patch(input, 6)
+
+  await run()
+
+  assert.deepStrictEqual(output.content, nothing)
+  patch(control, Belief(true, ["hello"]))
+
+  await run()
+
+  assert(
+    isBelief(output.content) &&
+      beliefEqual(output.content, Belief(6, ["hello"])),
+  )
+})

src/propagators/switcher.ts

@@ -1,5 +1,6 @@
 import { definePrimitive } from "../propagator/index.js"
 
+// For `switch` is preserved by JavaScript.
 export const switcher = definePrimitive(3, (control, input, output) => {
   if (control) return input
   else return output