feat(std/signal): add utility for listening to signal events (#4696)

1 files changed, 35 insertions, 1 deletions

diff --git a/std/signal/test.ts b/std/signal/test.ts
index 16d1458a2..e36a697a5 100644
--- a/std/signal/test.ts
+++ b/std/signal/test.ts
@@ -1,7 +1,7 @@
 const { test } = Deno;
 import { assertEquals, assertThrows } from "../testing/asserts.ts";
 import { delay } from "../util/async.ts";
-import { signal } from "./mod.ts";
+import { signal, onSignal } from "./mod.ts";
 
 if (Deno.build.os !== "win") {
   test("signal() throws when called with empty signals", (): void => {
@@ -58,4 +58,38 @@ if (Deno.build.os !== "win") {
       await delay(10);
     },
   });
+
+  test({
+    name: "onSignal() registers and disposes of event handler",
+    async fn() {
+      // This prevents the program from exiting.
+      const t = setInterval(() => {}, 1000);
+
+      let calledCount = 0;
+      const handle = onSignal(Deno.Signal.SIGINT, () => {
+        calledCount++;
+      });
+
+      await delay(20);
+      Deno.kill(Deno.pid, Deno.Signal.SIGINT);
+      await delay(20);
+      Deno.kill(Deno.pid, Deno.Signal.SIGINT);
+      await delay(20);
+      Deno.kill(Deno.pid, Deno.Signal.SIGUSR2);
+      await delay(20);
+      handle.dispose(); // stop monitoring SIGINT
+      await delay(20);
+      Deno.kill(Deno.pid, Deno.Signal.SIGUSR1);
+      await delay(20);
+      Deno.kill(Deno.pid, Deno.Signal.SIGINT);
+      await delay(20);
+      assertEquals(calledCount, 2);
+
+      clearTimeout(t);
+      // Clear timeout clears interval, but interval promise is not
+      // yet resolved, delay to next turn of event loop otherwise,
+      // we'll be leaking resources.
+      await delay(10);
+    },
+  });
 }