refactor: use consts, async/await, etc in rollingcache spec

- basically using pre-defined fixture vars instead of ones defined
  inside the test
  - which is more straightforward, easier to read, and less fragile
  - shorter names too
  - left a couple of ones as is where they were only used once very
    quickly -- could make them fixture vars too but 🤷

- use async/await instead of Promises with `done()` etc
- also use more `fs-extra` functions that support Promises instead of
  synchronous `fs` functions (e.g. `existsSync` -> `pathExists`)
  - async should be a small optimization for tests too

- fix: use __temp dir for auto-generated files instead of creating
  them in a fixtures dir and breaking actual fixtures

- format: a few multi-line statements were able to be condensed to a
  single line, so do so
  - esp as multi-line was not helping readability since this is just
    irrelevant test data (may have hampered readability actually)

__tests__/rollingcache.spec.ts

@@ -1,41 +1,35 @@
 import { beforeEach, afterAll, test, expect } from "@jest/globals";
 import * as path from "path";
-import * as fs from "fs";
-import { remove, ensureDir } from "fs-extra";
+import { remove, ensureDir, writeFile, pathExists } from "fs-extra";
 
 import { RollingCache } from "../src/rollingcache";
 
 
-const defaultTestFileShape = {
-	a: 1,
-	b: 2,
-	c: 3,
-};
 const local = (x: string) => path.resolve(__dirname, x);
+const testDir = local("__temp/rollingcache");
+const oldCacheDir = `${testDir}/cache`;
+const newCacheDir = `${testDir}/cache_`;
+const testFile = "file.json";
+const oldTestFile = `${oldCacheDir}/${testFile}`;
 
-beforeEach(() => {
-	// pre-create oldCacheRoot
-	return ensureDir(local("fixtures/cache")).then(() => {
-		// and newCacheRoot
-		return ensureDir(local("fixtures/cache_")).then(() => {
-			const testfile = local("fixtures/cache/testfile.json");
-			fs.writeFileSync(testfile, JSON.stringify(defaultTestFileShape), "utf8");
-		});
-	});
+const nonExistentFile = "this-does-not-exist.json";
+const emptyCacheRoot = `${testDir}/empty-cache-root`;
+
+const testFileShape = { a: 1, b: 2, c: 3 };
+
+
+beforeEach(async () => {
+	await ensureDir(oldCacheDir);
+	await ensureDir(newCacheDir);
+	await writeFile(oldTestFile, JSON.stringify(testFileShape), "utf8");
 });
+afterAll(() => remove(testDir));
 
-afterAll(
-	() => Promise.all([
-		remove(local("fixtures")),
-		remove(local("not-real")),
-	]),
-);
 
-test("RollingCache", () => {
+test("RollingCache", async () => {
 	expect(RollingCache).toBeTruthy();
 
-	const cacheRoot = local("fixtures");
-	const cache = new RollingCache(cacheRoot, true);
+	const cache = new RollingCache(testDir, true);
 	expect(Object.keys(cache)).toEqual([
 		"cacheRoot",
 		"checkNewCache",
@@ -44,35 +38,30 @@ test("RollingCache", () => {
 		"newCacheRoot",
 	]);
 
-	expect(cache.exists("fake-file.json")).toBeFalsy();
-	expect(cache.exists("testfile.json")).toBeTruthy();
-	expect(cache.path("x")).toEqual(local("fixtures/cache/x"));
-	expect(cache.match(["fake-file.json"])).toBeFalsy();
-	expect(cache.match(["testfile.json"])).toBeTruthy();
-	expect(cache.read("testfile.json")).toEqual(defaultTestFileShape);
+	expect(cache.exists(nonExistentFile)).toBeFalsy();
+	expect(cache.exists(testFile)).toBeTruthy();
+	expect(cache.path("x")).toEqual(`${oldCacheDir}/x`);
+	expect(cache.match([nonExistentFile])).toBeFalsy();
+	expect(cache.match([testFile])).toBeTruthy();
+	expect(cache.read(testFile)).toEqual(testFileShape);
 
 	cache.write("write-test.json", {a: 2, b: 2, c: 2});
-	expect(
-		cache.read("write-test.json"),
-	).toEqual({a: 2, b: 2, c: 2});
+	expect(cache.read("write-test.json")).toEqual({a: 2, b: 2, c: 2});
 
 	cache.write("write-fail.json", (undefined as any));
-	expect(
-		cache.read("write-fail.json"),
-	).toBeFalsy();
+	expect(cache.read("write-fail.json")).toBeFalsy();
 
 	cache.touch("touched.json");
-	expect(fs.existsSync(local("fixtures/cache_/touched.json"))).toBeTruthy();
+	expect(await pathExists(`${newCacheDir}/touched.json`)).toBeTruthy();
 	expect((cache as any).rolled).toBeFalsy();
 
 	cache.roll();
 	expect((cache as any).rolled).toBeTruthy();
-	expect(fs.existsSync(local("fixtures/cache_"))).toBeFalsy();
+	expect(await pathExists(newCacheDir)).toBeFalsy();
 });
 
-test("RollingCache, rolled", () => {
-	const cacheRoot = local("fixtures");
-	const cache = new RollingCache(cacheRoot, true);
+test("RollingCache, rolled", async () => {
+	const cache = new RollingCache(testDir, true);
 	// roll the cache
 	cache.roll();
 	// rolling again hits coverage for this.rolled being true already
@@ -81,28 +70,23 @@ test("RollingCache, rolled", () => {
 	expect(cache.match([])).toBeFalsy();
 
 	cache.write("whatever.json", {whatever: true});
-	expect(fs.existsSync(local("fixtures/cache/whatever.json"))).toBeFalsy();
+	expect(await pathExists(`${oldCacheDir}/whatever.json`)).toBeFalsy();
 
 	cache.touch("touched.json");
-	expect(fs.existsSync(local("fixtures/cache/touched.json"))).toBeFalsy();
+	expect(await pathExists(`${oldCacheDir}/touched.json`)).toBeFalsy();
 });
 
-test("RollingCache, test checkNewCache", (done) => {
-	const cacheRoot = local("fixtures");
-	const cache = new RollingCache(cacheRoot, true);
+test("RollingCache, test checkNewCache", async () => {
+	const cache = new RollingCache(testDir, true);
 
-	const preExistingTestFile = local("fixtures/cache_/pre-existing.json");
-	fs.writeFile(preExistingTestFile, JSON.stringify({}), "utf8", (e?: Error) => {
-		if (e) console.log(e);
-		expect(cache.exists("pre-existing.json")).toBeTruthy();
-		done();
-	});
+	const preExistingFile = `${newCacheDir}/pre-existing.json`;
+	await writeFile(preExistingFile, JSON.stringify({}));
+	expect(cache.exists("pre-existing.json")).toBeTruthy();
 });
 
-test("RollingCache, test match when oldCacheRoot is empty", () => {
-	const cacheRoot = local("not-real");
-	const cache = new RollingCache(cacheRoot, true);
+test("RollingCache, test match when oldCacheDir is empty", () => {
+	const cache = new RollingCache(emptyCacheRoot, true);
 
 	expect(cache.match([])).toBeTruthy();
-	expect(cache.match(["file.json"])).toBeFalsy();
+	expect(cache.match([testFile])).toBeFalsy();
 });