Add getSyncStartableStoppable and tests

Signed-off-by: Sebastian Malton <sebastian@malton.name>

src/common/utils/get-startable-stoppable.test.ts

@@ -4,14 +4,15 @@
  */
 import type { AsyncFnMock } from "@async-fn/jest";
 import asyncFn from "@async-fn/jest";
-import { getStartableStoppable } from "./get-startable-stoppable";
+import type { StartableStoppable, SyncStartableStoppable } from "./get-startable-stoppable";
+import { getSyncStartableStoppable, getStartableStoppable } from "./get-startable-stoppable";
 import { getPromiseStatus } from "../test-utils/get-promise-status";
 import { flushPromises } from "../test-utils/flush-promises";
 
 describe("getStartableStoppable", () => {
   let stopMock: AsyncFnMock<() => Promise<void>>;
   let startMock: AsyncFnMock<() => Promise<() => Promise<void>>>;
-  let actual: { stop: () => Promise<void>; start: () => Promise<void>; started: boolean };
+  let actual: StartableStoppable;
 
   beforeEach(() => {
     stopMock = asyncFn();
@@ -29,7 +30,7 @@ describe("getStartableStoppable", () => {
   });
 
   it("when stopping before ever starting, throws", () => {
-    expect(actual.stop).rejects.toThrow("Tried to stop \"some-id\", but it has not started yet.");
+    expect(async () => actual.stop()).rejects.toThrow("Tried to stop \"some-id\", but it is already stopped.");
   });
 
   it("is not started", () => {
@@ -71,7 +72,7 @@ describe("getStartableStoppable", () => {
       });
 
       it("throws", () => {
-        expect(error.message).toBe("Tried to start \"some-id\", but it is already being started.");
+        expect(error.message).toBe("Tried to start \"some-id\", but it is already starting.");
       });
     });
 
@@ -91,7 +92,7 @@ describe("getStartableStoppable", () => {
       });
 
       it("when started again, throws", () => {
-        expect(actual.start).rejects.toThrow("Tried to start \"some-id\", but it has already started.");
+        expect(actual.start).rejects.toThrow("Tried to start \"some-id\", but it is already started.");
       });
 
       it("does not stop yet", () => {
@@ -135,7 +136,7 @@ describe("getStartableStoppable", () => {
           });
 
           it("when stopped again, throws", () => {
-            expect(actual.stop).rejects.toThrow("Tried to stop \"some-id\", but it has already stopped.");
+            expect(actual.stop).rejects.toThrow("Tried to stop \"some-id\", but it is already stopped.");
           });
 
           describe("when started again", () => {
@@ -233,3 +234,59 @@ describe("getStartableStoppable", () => {
     });
   });
 });
+
+describe("getSyncStartableStoppable", () => {
+  let stopMock: jest.MockedFunction<() => void>;
+  let startMock: jest.MockedFunction<() => () => void>;
+  let actual: SyncStartableStoppable;
+
+  beforeEach(() => {
+    stopMock = jest.fn();
+    startMock = jest.fn().mockImplementation(() => stopMock);
+    actual = getSyncStartableStoppable("some-id", startMock);
+  });
+
+  it("does not start yet", () => {
+    expect(startMock).not.toHaveBeenCalled();
+  });
+
+  it("does not stop yet", () => {
+    expect(stopMock).not.toHaveBeenCalled();
+  });
+
+  it("when stopping before ever starting, throws", () => {
+    expect(() => actual.stop()).toThrow("Tried to stop \"some-id\", but it is already stopped.");
+  });
+
+  it("is not started", () => {
+    expect(actual.started).toBe(false);
+  });
+
+  describe("when started", () => {
+    beforeEach(() => {
+      actual.start();
+    });
+
+    it("calls start function", () => {
+      expect(startMock).toHaveBeenCalled();
+    });
+
+    it("is started", () => {
+      expect(actual.started).toBe(true);
+    });
+
+    describe("when stopped", () => {
+      beforeEach(() => {
+        actual.stop();
+      });
+
+      it("calls stop function", () => {
+        expect(stopMock).toBeCalled();
+      });
+
+      it("is stopped", () => {
+        expect(actual.started).toBe(false);
+      });
+    });
+  });
+});

src/common/utils/get-startable-stoppable.ts

@@ -3,58 +3,85 @@
  * Licensed under MIT License. See LICENSE in root directory for more information.
  */
 
-type Stopper = () => Promise<void> | void;
-type Starter = () => Promise<Stopper> | Stopper;
+export type Stopper = () => Promise<void> | void;
+export type Starter = () => Promise<Stopper> | Stopper;
 
-export const getStartableStoppable = (
-  id: string,
-  startAndGetStopCallback: Starter,
-) => {
+export type SyncStopper = () => void;
+export type SyncStarter = () => SyncStopper;
+
+export interface SyncStartableStoppable {
+  readonly started: boolean;
+  start: () => void;
+  stop: () => void;
+}
+
+export interface StartableStoppable {
+  readonly started: boolean;
+  start: () => Promise<void>;
+  stop: () => Promise<void>;
+}
+
+type StartableStoppableState = "stopped" | "started" | "starting";
+
+export function getSyncStartableStoppable(id: string, syncStartAndGetSyncStopper: SyncStarter): SyncStartableStoppable {
   let stop: Stopper;
-  let stopped = false;
-  let started = false;
-  let starting = false;
+  let state: StartableStoppableState = "stopped";
+
+  return {
+    get started() {
+      return state === "started";
+    },
+
+    start: (): void | Promise<void> => {
+      if (state !== "stopped") {
+        throw new Error(`Tried to start "${id}", but it is already ${state}.`);
+      }
+
+      state = "starting";
+      stop = syncStartAndGetSyncStopper();
+      state = "started";
+    },
+
+    stop: (): void | Promise<void> => {
+      if (state !== "started") {
+        throw new Error(`Tried to stop "${id}", but it is already ${state}.`);
+      }
+
+      stop();
+      state = "stopped";
+    },
+  };
+}
+
+export function getStartableStoppable(id: string, startAndGetStopCallback: Starter): StartableStoppable {
+  let stop: Stopper;
+  let state: StartableStoppableState = "stopped";
   let startingPromise: Promise<Stopper> | Stopper;
 
   return {
     get started() {
-      return started;
+      return state === "started";
     },
 
     start: async () => {
-      if (starting) {
-        throw new Error(`Tried to start "${id}", but it is already being started.`);
-      }
-
-      starting = true;
-
-      if (started) {
-        throw new Error(`Tried to start "${id}", but it has already started.`);
+      if (state !== "stopped") {
+        throw new Error(`Tried to start "${id}", but it is already ${state}.`);
       }
 
+      state = "starting";
       startingPromise = startAndGetStopCallback();
       stop = await startingPromise;
-
-      stopped = false;
-      started = true;
-      starting = false;
+      state = "started";
     },
 
     stop: async () => {
+      if (state === "stopped") {
+        throw new Error(`Tried to stop "${id}", but it is already ${state}.`);
+      }
+
       await startingPromise;
-
-      if (stopped) {
-        throw new Error(`Tried to stop "${id}", but it has already stopped.`);
-      }
-
-      if (!started) {
-        throw new Error(`Tried to stop "${id}", but it has not started yet.`);
-      }
-
       await stop();
-
-      started = false;
-      stopped = true;
+      state = "stopped";
     },
   };
-};
+}