3 files changed, 124 insertions, 0 deletions
diff --git a/spec/frontend_integration/test_helpers/utils/obj.js b/spec/frontend_integration/test_helpers/utils/obj.js
new file mode 100644
index 00000000000..6c301798489
--- /dev/null
+++ b/spec/frontend_integration/test_helpers/utils/obj.js
@@ -0,0 +1,36 @@
+import { has, mapKeys, pick } from 'lodash';
+
+/**
+ * This method is used to type-safely set values on the given object
+ *
+ * @template T
+ * @returns {T} A shallow copy of `obj`, with the values from `values`
+ * @throws {Error} If `values` contains a key that isn't already on `obj`
+ * @param {T} source
+ * @param {Object} values
+ */
+export const withValues = (source, values) =>
+  Object.entries(values).reduce(
+    (acc, [key, value]) => {
+      if (!has(acc, key)) {
+        throw new Error(
+          `[mock_server] Cannot write property that does not exist on object '${key}'`,
+        );
+      }
+
+      return {
+        ...acc,
+        [key]: value,
+      };
+    },
+    { ...source },
+  );
+
+/**
+ * This method returns a subset of the given object and maps the key names based on the
+ * given `keys`.
+ *
+ * @param {Object} obj The source object.
+ * @param {Object} map The object which contains the keys to use and mapped key names.
+ */
+export const withKeys = (obj, map) => mapKeys(pick(obj, Object.keys(map)), (val, key) => map[key]);
diff --git a/spec/frontend_integration/test_helpers/utils/obj_spec.js b/spec/frontend_integration/test_helpers/utils/obj_spec.js
new file mode 100644
index 00000000000..0ad7b4a1a4c
--- /dev/null
+++ b/spec/frontend_integration/test_helpers/utils/obj_spec.js
@@ -0,0 +1,23 @@
+import { withKeys, withValues } from './obj';
+
+describe('frontend_integration/test_helpers/utils/obj', () => {
+  describe('withKeys', () => {
+    it('picks and maps keys', () => {
+      expect(withKeys({ a: '123', b: 456, c: 'd' }, { b: 'lorem', c: 'ipsum', z: 'zed ' })).toEqual(
+        { lorem: 456, ipsum: 'd' },
+      );
+    });
+  });
+
+  describe('withValues', () => {
+    it('sets values', () => {
+      expect(withValues({ a: '123', b: 456 }, { b: 789 })).toEqual({ a: '123', b: 789 });
+    });
+
+    it('throws if values has non-existent key', () => {
+      expect(() => withValues({ a: '123', b: 456 }, { b: 789, bogus: 'throws' })).toThrow(
+        `[mock_server] Cannot write property that does not exist on object 'bogus'`,
+      );
+    });
+  });
+});
diff --git a/spec/frontend_integration/test_helpers/utils/overclock_timers.js b/spec/frontend_integration/test_helpers/utils/overclock_timers.js
new file mode 100644
index 00000000000..046c7f8e527
--- /dev/null
+++ b/spec/frontend_integration/test_helpers/utils/overclock_timers.js
@@ -0,0 +1,65 @@
+/**
+ * This function replaces the existing `setTimeout` and `setInterval` with wrappers that
+ * discount the `ms` passed in by `boost`.
+ *
+ * For example, if a module has:
+ *
+ * ```
+ * setTimeout(cb, 100);
+ * ```
+ *
+ * But a test has:
+ *
+ * ```
+ * useOverclockTimers(25);
+ * ```
+ *
+ * Then the module's call to `setTimeout` effectively becomes:
+ *
+ * ```
+ * setTimeout(cb, 4);
+ * ```
+ *
+ * It's important to note that the timing for `setTimeout` and order of execution is non-deterministic
+ * and discounting the `ms` passed could make this very obvious and expose some underlying issues
+ * with flaky failures.
+ *
+ * WARNING: If flaky spec failures show up in a spec that is using this helper, please consider either:
+ *
+ *   - Refactoring the production code so that it's reactive to state changes, not dependent on timers.
+ *   - Removing the call to this helper from the spec.
+ *
+ * @param {Number} boost
+ */
+// eslint-disable-next-line import/prefer-default-export
+export const useOverclockTimers = (boost = 50) => {
+  if (boost <= 0) {
+    throw new Error(`[overclock_timers] boost (${boost}) cannot be <= 0`);
+  }
+
+  let origSetTimeout;
+  let origSetInterval;
+  const newSetTimeout = (fn, msParam = 0) => {
+    const ms = msParam > 0 ? Math.floor(msParam / boost) : msParam;
+
+    return origSetTimeout(fn, ms);
+  };
+  const newSetInterval = (fn, msParam = 0) => {
+    const ms = msParam > 0 ? Math.floor(msParam / boost) : msParam;
+
+    return origSetInterval(fn, ms);
+  };
+
+  beforeEach(() => {
+    origSetTimeout = global.setTimeout;
+    origSetInterval = global.setInterval;
+
+    global.setTimeout = newSetTimeout;
+    global.setInterval = newSetInterval;
+  });
+
+  afterEach(() => {
+    global.setTimeout = origSetTimeout;
+    global.setInterval = origSetInterval;
+  });
+};