Hold event loop during main()

lib/main.ts

@@ -67,6 +67,10 @@ export async function main(
       // this function in the exit context so it can be called anywhere.
       yield* ExitContext.set(resolve);
 
+      // this will hold the event loop and prevent runtimes such as
+      // Node and Deno from exiting prematurely.
+      let interval = setInterval(() => {}, Math.pow(2, 30));
+
       try {
         let interrupt = () => resolve({ status: 130, signal: "SIGINT" });
         yield* withHost({
@@ -105,6 +109,8 @@ export async function main(
         yield* exit(0);
       } catch (error) {
         resolve({ status: 1, error });
+      } finally {
+        clearInterval(interval);
       }
     })
   );

test/main.test.ts

@@ -83,6 +83,25 @@ describe("main", () => {
       expect(status.code).toEqual(1);
     });
   });
+
+  it("works even if suspend is the only operation", async () => {
+    await run(function* () {
+      let process = yield* useCommand("deno", {
+        stdout: "piped",
+        args: ["run", "test/main/just.suspend.ts"],
+      });
+      let stdout = yield* buffer(process.stdout);
+      yield* detect(stdout, "started");
+
+      process.kill("SIGINT");
+
+      let status = yield* process.status;
+
+      expect(status.code).toBe(130);
+
+      yield* detect(stdout, "gracefully stopped");
+    });
+  });
 });
 
 import type { Operation } from "../lib/types.ts";

test/main/just.suspend.ts

@@ -0,0 +1,11 @@
+import { suspend } from "../../lib/instructions.ts";
+import { main } from "../../lib/main.ts";
+
+await main(function* () {
+  console.log("started");
+  try {
+    yield* suspend();
+  } finally {
+    console.log("gracefully stopped");
+  }
+});