Adds setInitialCacheTimestamp method for consistent cache timestamps,

11ty/eleventy-img#146

src/AssetCache.js

@@ -9,6 +9,8 @@ const debug = require("debug")("Eleventy:Fetch");
 
 class AssetCache {
 	#customFilename;
+	#hasSaved = false;
+	#cacheLocationDirty = false;
 
 	constructor(source, cacheDirectory, options = {}) {
 		if(!Sources.isValidSource(source)) {
@@ -33,6 +35,14 @@ class AssetCache {
 		}
 	}
 
+	setInitialCacheTimestamp(timestamp) {
+		this.initialCacheTimestamp = timestamp;
+
+		if(this.#hasSaved) {
+			throw new Error("`setInitialCacheTimestamp` method must be called before the object is saved.");
+		}
+	}
+
 	log(message) {
 		if (this.options.verbose) {
 			console.log(`[11ty/eleventy-fetch] ${message}`);
@@ -110,7 +120,7 @@ class AssetCache {
 
 	set hash(value) {
 		if (value !== this._hash) {
-			this._cacheLocationDirty = true;
+			this.#cacheLocationDirty = true;
 		}
 
 		this._hash = value;
@@ -122,7 +132,7 @@ class AssetCache {
 
 	set cacheDirectory(dir) {
 		if (dir !== this._cacheDirectory) {
-			this._cacheLocationDirty = true;
+			this.#cacheLocationDirty = true;
 		}
 
 		this._cacheDirectory = dir;
@@ -160,14 +170,14 @@ class AssetCache {
 	}
 
 	get cache() {
-		if (!this._cache || this._cacheLocationDirty) {
+		if (!this._cache || this.#cacheLocationDirty) {
 			let cache = FlatCacheCreate({
 				cacheId: this.cacheFilename,
 				cacheDir: this.rootDir,
 			});
 
 			this._cache = cache;
-			this._cacheLocationDirty = false;
+			this.#cacheLocationDirty = false;
 		}
 		return this._cache;
 	}
@@ -222,9 +232,16 @@ class AssetCache {
 	async save(contents, type = "buffer", metadata = {}) {
 		if (this.options.dryRun) {
 			debug("An attempt was made to save to the file system with `dryRun: true`. Skipping.");
+
+			// Errors are still expected from this
+			this.#hasSaved = true;
 			return;
 		}
 
+		if(!contents) {
+			throw new Error("save(contents) expects contents (it was falsy)");
+		}
+
 		if(!this.isDirEnsured) {
 			this.ensureDir();
 		}
@@ -241,12 +258,13 @@ class AssetCache {
 		debug(`Writing ${contentPath}`);
 
 		this.cache.set(this.hash, {
-			cachedAt: Date.now(),
+			cachedAt: this.initialCacheTimestamp || Date.now(),
 			type: type,
 			metadata,
 		});
 
 		this.cache.save();
+		this.#hasSaved = true;
 	}
 
 	async getCachedContents(type) {
@@ -291,6 +309,10 @@ class AssetCache {
 		return this.getCachedContents(type);
 	}
 
+	getCachedTimestamp() {
+		return this.cachedObject?.cachedAt || this.initialCacheTimestamp;
+	}
+
 	isCacheValid(duration = this.defaultDuration) {
 		if (!this.cachedObject) {
 			// not cached

test/AssetCacheTest.js

@@ -137,3 +137,30 @@ test("Uses filenameFormat", async (t) => {
 	t.falsy(fs.existsSync(cachePath));
 	t.falsy(fs.existsSync(jsonCachePath));
 });
+
+test("setInitialCacheTimestamp method (used by Eleventy Image to establish a consistent cached file name in synchronous contexts)", async (t) => {
+	let cache = new AssetCache("this_is_a_test", ".cache", {
+		dryRun: true
+	});
+	let timestamp = Date.now();
+	cache.setInitialCacheTimestamp(timestamp);
+
+	await cache.save("test");
+
+	t.is(cache.getCachedTimestamp(), timestamp);
+});
+
+test("setInitialCacheTimestamp method after save throws error", async (t) => {
+	let cache = new AssetCache("this_is_a_test", ".cache", {
+		dryRun: true
+	});
+	let timestamp = Date.now();
+
+	await cache.save("test");
+
+	t.throws(() => {
+		cache.setInitialCacheTimestamp(timestamp);
+	}, {
+		message: "`setInitialCacheTimestamp` method must be called before the object is saved."
+	})
+});