Add tests for healthchecks reducer

Summary:
Quite a bit of complex slicing going on there, so I think
this is quite useful to guard against future breakages.

Reviewed By: jknoxville

Differential Revision: D18853033

fbshipit-source-id: 36b17b8ce208cb320a193bceed86c89e010107e4

src/reducers/__tests__/healthchecks.node.tsx

@@ -0,0 +1,91 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {
+  default as reducer,
+  initHealthcheckReport,
+  startHealthchecks,
+  HealthcheckReportCategory,
+  HealthcheckReportItem,
+  finishHealthchecks,
+  updateHealthcheckReportItem,
+} from '../healthchecks';
+
+const HEALTHCHECK_ITEM: HealthcheckReportItem = {
+  label: 'Test Check',
+  status: 'WARNING',
+  message: "Something didn't quite work.",
+};
+
+const HEALTHCHECK_CATEGORY: HealthcheckReportCategory = {
+  label: 'Test Category',
+  status: 'WARNING',
+  checks: [HEALTHCHECK_ITEM],
+};
+
+test('initHealthcheckReport', () => {
+  const report = {
+    isHealthcheckInProgress: false,
+    categories: [],
+  };
+  const res = reducer(undefined, initHealthcheckReport(report));
+  expect(res.healthcheckReport).toEqual(report);
+});
+
+test('startHealthCheck', () => {
+  const report = {
+    isHealthcheckInProgress: false,
+    categories: [HEALTHCHECK_CATEGORY],
+  };
+  let res = reducer(undefined, initHealthcheckReport(report));
+  res = reducer(res, startHealthchecks());
+  expect(res.healthcheckReport.isHealthcheckInProgress).toBeTruthy();
+  // This seems trivial, but by getting the spread wrong, it's easy
+  // to break this.
+  expect(res.healthcheckReport.categories).toEqual([HEALTHCHECK_CATEGORY]);
+});
+
+test('finish', () => {
+  const report = {
+    isHealthcheckInProgress: true,
+    categories: [HEALTHCHECK_CATEGORY],
+  };
+  let res = reducer(undefined, initHealthcheckReport(report));
+  res = reducer(res, finishHealthchecks());
+  expect(res.healthcheckReport.isHealthcheckInProgress).toBeFalsy();
+  expect(res.healthcheckReport.categories).toEqual([HEALTHCHECK_CATEGORY]);
+});
+
+test('updateHealthcheck', () => {
+  const report = {
+    isHealthcheckInProgress: true,
+    categories: [HEALTHCHECK_CATEGORY, HEALTHCHECK_CATEGORY],
+  };
+  let res = reducer(undefined, initHealthcheckReport(report));
+  res = reducer(
+    res,
+    updateHealthcheckReportItem(0, 0, {
+      label: 'Updated Test Item',
+      status: 'SUCCESS',
+    }),
+  );
+  expect(res.healthcheckReport.isHealthcheckInProgress).toBeTruthy();
+  expect(res.healthcheckReport.categories[0].checks[0].label).toEqual(
+    'Updated Test Item',
+  );
+  expect(res.healthcheckReport.categories[0].checks[0].status).toEqual(
+    'SUCCESS',
+  );
+  expect(res.healthcheckReport.categories[1].checks[0].label).toEqual(
+    'Test Check',
+  );
+  expect(res.healthcheckReport.categories[1].checks[0].status).toEqual(
+    'WARNING',
+  );
+});