1 files changed, 142 insertions, 0 deletions
diff --git a/browser/components/newtab/test/unit/lib/PersistentCache.test.js b/browser/components/newtab/test/unit/lib/PersistentCache.test.js
new file mode 100644
index 0000000000..e645b8d398
--- /dev/null
+++ b/browser/components/newtab/test/unit/lib/PersistentCache.test.js
@@ -0,0 +1,142 @@
+import { GlobalOverrider } from "test/unit/utils";
+import { PersistentCache } from "lib/PersistentCache.sys.mjs";
+
+describe("PersistentCache", () => {
+  let fakeIOUtils;
+  let fakePathUtils;
+  let cache;
+  let filename = "cache.json";
+  let consoleErrorStub;
+  let globals;
+  let sandbox;
+
+  beforeEach(() => {
+    globals = new GlobalOverrider();
+    sandbox = sinon.createSandbox();
+    fakeIOUtils = {
+      writeJSON: sinon.stub().resolves(0),
+      readJSON: sinon.stub().resolves({}),
+    };
+    fakePathUtils = {
+      join: sinon.stub().returns(filename),
+      localProfileDir: "/",
+    };
+    consoleErrorStub = sandbox.stub();
+    globals.set("console", { error: consoleErrorStub });
+    globals.set("IOUtils", fakeIOUtils);
+    globals.set("PathUtils", fakePathUtils);
+
+    cache = new PersistentCache(filename);
+  });
+  afterEach(() => {
+    globals.restore();
+    sandbox.restore();
+  });
+
+  describe("#get", () => {
+    it("tries to read the file", async () => {
+      await cache.get("foo");
+      assert.calledOnce(fakeIOUtils.readJSON);
+    });
+    it("doesnt try to read the file if it was already loaded", async () => {
+      await cache._load();
+      fakeIOUtils.readJSON.resetHistory();
+      await cache.get("foo");
+      assert.notCalled(fakeIOUtils.readJSON);
+    });
+    it("should catch and report errors", async () => {
+      fakeIOUtils.readJSON.rejects(new SyntaxError("Failed to parse JSON"));
+      await cache._load();
+      assert.calledOnce(consoleErrorStub);
+
+      cache._cache = undefined;
+      consoleErrorStub.resetHistory();
+
+      fakeIOUtils.readJSON.rejects(
+        new DOMException("IOUtils shutting down", "AbortError")
+      );
+      await cache._load();
+      assert.calledOnce(consoleErrorStub);
+
+      cache._cache = undefined;
+      consoleErrorStub.resetHistory();
+
+      fakeIOUtils.readJSON.rejects(
+        new DOMException("File not found", "NotFoundError")
+      );
+      await cache._load();
+      assert.notCalled(consoleErrorStub);
+    });
+    it("returns data for a given cache key", async () => {
+      fakeIOUtils.readJSON.resolves({ foo: "bar" });
+      let value = await cache.get("foo");
+      assert.equal(value, "bar");
+    });
+    it("returns undefined for a cache key that doesn't exist", async () => {
+      let value = await cache.get("baz");
+      assert.equal(value, undefined);
+    });
+    it("returns all the data if no cache key is specified", async () => {
+      fakeIOUtils.readJSON.resolves({ foo: "bar" });
+      let value = await cache.get();
+      assert.deepEqual(value, { foo: "bar" });
+    });
+  });
+
+  describe("#set", () => {
+    it("tries to read the file on the first set", async () => {
+      await cache.set("foo", { x: 42 });
+      assert.calledOnce(fakeIOUtils.readJSON);
+    });
+    it("doesnt try to read the file if it was already loaded", async () => {
+      cache = new PersistentCache(filename, true);
+      await cache._load();
+      fakeIOUtils.readJSON.resetHistory();
+      await cache.set("foo", { x: 42 });
+      assert.notCalled(fakeIOUtils.readJSON);
+    });
+    it("sets a string value", async () => {
+      const key = "testkey";
+      const value = "testvalue";
+      await cache.set(key, value);
+      const cachedValue = await cache.get(key);
+      assert.equal(cachedValue, value);
+    });
+    it("sets an object value", async () => {
+      const key = "testkey";
+      const value = { x: 1, y: 2, z: 3 };
+      await cache.set(key, value);
+      const cachedValue = await cache.get(key);
+      assert.deepEqual(cachedValue, value);
+    });
+    it("writes the data to file", async () => {
+      const key = "testkey";
+      const value = { x: 1, y: 2, z: 3 };
+
+      await cache.set(key, value);
+      assert.calledOnce(fakeIOUtils.writeJSON);
+      assert.calledWith(
+        fakeIOUtils.writeJSON,
+        filename,
+        { [[key]]: value },
+        { tmpPath: `${filename}.tmp` }
+      );
+    });
+    it("throws when failing to get file path", async () => {
+      Object.defineProperty(fakePathUtils, "localProfileDir", {
+        get() {
+          throw new Error();
+        },
+      });
+
+      let rejected = false;
+      try {
+        await cache.set("key", "val");
+      } catch (error) {
+        rejected = true;
+      }
+
+      assert(rejected);
+    });
+  });
+});