1 files changed, 90 insertions, 0 deletions
diff --git a/toolkit/components/nimbus/test/browser/browser_experimentstore_load.js b/toolkit/components/nimbus/test/browser/browser_experimentstore_load.js
new file mode 100644
index 0000000000..a6f526e764
--- /dev/null
+++ b/toolkit/components/nimbus/test/browser/browser_experimentstore_load.js
@@ -0,0 +1,90 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ExperimentStore } = ChromeUtils.importESModule(
+  "resource://nimbus/lib/ExperimentStore.sys.mjs"
+);
+const { ExperimentFakes } = ChromeUtils.importESModule(
+  "resource://testing-common/NimbusTestUtils.sys.mjs"
+);
+const { ExperimentFeatures } = ChromeUtils.importESModule(
+  "resource://nimbus/ExperimentAPI.sys.mjs"
+);
+ChromeUtils.defineESModuleGetters(this, {
+  JSONFile: "resource://gre/modules/JSONFile.sys.mjs",
+});
+
+function getPath() {
+  const profileDir = Services.dirsvc.get("ProfD", Ci.nsIFile).path;
+  // NOTE: If this test is failing because you have updated this path in `ExperimentStore`,
+  // users will lose their old experiment data. You should do something to migrate that data.
+  return PathUtils.join(profileDir, "ExperimentStoreData.json");
+}
+
+// Ensure that data persisted to disk is succesfully loaded by the store.
+// We write data to the expected location in the user profile and
+// instantiate an ExperimentStore that should then see the value.
+add_task(async function test_loadFromFile() {
+  const previousSession = new JSONFile({ path: getPath() });
+  await previousSession.load();
+  previousSession.data.test = {
+    slug: "test",
+    active: true,
+    lastSeen: Date.now(),
+  };
+  previousSession.saveSoon();
+  await previousSession.finalize();
+
+  // Create a store and expect to load data from previous session
+  const store = new ExperimentStore();
+
+  await store.init();
+  await store.ready();
+
+  Assert.equal(
+    previousSession.path,
+    store._store.path,
+    "Should have the same path"
+  );
+
+  Assert.ok(
+    store.get("test"),
+    "This should pass if the correct store path loaded successfully"
+  );
+});
+
+add_task(async function test_load_from_disk_event() {
+  const experiment = ExperimentFakes.experiment("foo", {
+    branch: {
+      slug: "variant",
+      features: [{ featureId: "green" }],
+    },
+    lastSeen: Date.now(),
+  });
+  const stub = sinon.stub();
+  const previousSession = new JSONFile({ path: getPath() });
+  await previousSession.load();
+  previousSession.data.foo = experiment;
+  previousSession.saveSoon();
+  await previousSession.finalize();
+
+  // Create a store and expect to load data from previous session
+  const store = new ExperimentStore();
+
+  store._onFeatureUpdate("green", stub);
+
+  await store.init();
+  await store.ready();
+
+  Assert.equal(
+    previousSession.path,
+    store._store.path,
+    "Should have the same path as previousSession."
+  );
+
+  await TestUtils.waitForCondition(() => stub.called, "Stub was called");
+
+  Assert.ok(stub.firstCall.args[1], "feature-experiment-loaded");
+});