fix: allow singular rate frequencies (#187)

e.g. 'hour' not just 'hours'

src/resources/schedule.test.ts

@@ -12,8 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 import * as faas from '../faas/index';
-import { schedule, RateWorkerOptions } from '.';
-
+import { schedule, RateWorkerOptions, Frequency } from '.';
 jest.mock('../faas/index');
 
 describe('Schedule', () => {
@@ -83,7 +82,7 @@ describe('Schedule', () => {
     });
   });
 
-  ['day', 'hour', 'minute'].forEach((rate) => {
+  ['day', 'hour', 'minute'].forEach((rate: Frequency) => {
     describe(`when create a new schedule with rate ${rate}`, () => {
       afterAll(() => {
         jest.resetAllMocks();
@@ -101,7 +100,7 @@ describe('Schedule', () => {
         const expectedOpts = new RateWorkerOptions(
           'main',
           1,
-          `${rate}s` as any
+          `${rate}s` as Frequency
         );
         expect(faas.Faas).toBeCalledWith(expectedOpts);
       });
@@ -111,4 +110,29 @@ describe('Schedule', () => {
       });
     });
   });
+
+  ['days', 'hours', 'minutes'].forEach((rate: Frequency) => {
+    describe(`when create a new schedule with rate ${rate}`, () => {
+      afterAll(() => {
+        jest.resetAllMocks();
+      });
+
+      beforeAll(async () => {
+        await schedule('main').every(`7 ${rate}`, mockFn);
+      });
+
+      it('should create a new FaasClient', () => {
+        expect(faas.Faas).toBeCalledTimes(1);
+      });
+
+      it('should provide Faas with ApiWorkerOptions', () => {
+        const expectedOpts = new RateWorkerOptions('main', 7, rate);
+        expect(faas.Faas).toBeCalledWith(expectedOpts);
+      });
+
+      it('should call FaasClient::start()', () => {
+        expect(startSpy).toBeCalledTimes(1);
+      });
+    });
+  });
 });

src/resources/schedule.ts

@@ -13,9 +13,16 @@
 // limitations under the License.
 import { EventMiddleware, Faas, ScheduleMiddleware } from '../faas';
 
-type Frequency = 'days' | 'hours' | 'minutes';
+const Frequencies = [
+  'day',
+  'days',
+  'hour',
+  'hours',
+  'minute',
+  'minutes',
+] as const;
 
-const FREQUENCIES: Frequency[] = ['days', 'hours', 'minutes'];
+export type Frequency = (typeof Frequencies)[number];
 
 export class RateWorkerOptions {
   public readonly description: string;
@@ -65,9 +72,11 @@ class Rate {
       );
     }
 
-    if (!FREQUENCIES.includes(normalizedFrequency)) {
+    if (!Frequencies.includes(normalizedFrequency)) {
       throw new Error(
-        `invalid rate expression, frequency must be one of ${FREQUENCIES}, received ${frequency}`
+        `invalid rate expression, frequency must one of [${Frequencies.join(
+          ', '
+        )}] received ${frequency}`
       );
     }
 
@@ -122,7 +131,7 @@ class Schedule {
   /**
    * Run this schedule on the provided frequency.
    *
-   * @param rate to run the schedule, e.g. '7 days'. All rates accept a number and a frequency. Valid frequencies are 'days', 'hours' or 'minutes'.
+   * @param rate to run the schedule, e.g. '7 days'. All rates accept a number and a frequency. Valid frequencies are 'day/days', 'hour/hours' or 'minute/minutes'.
    * @param middleware the handler/middleware to run on a schedule
    * @returns A promise that resolves when the schedule worker stops running.
    */
@@ -131,7 +140,7 @@ class Schedule {
     ...middleware: ScheduleMiddleware[]
   ): Promise<void> => {
     // handle singular frequencies. e.g. schedule('something').every('day')
-    if (FREQUENCIES.indexOf(`${rate}s` as Frequency) !== -1) {
+    if (Frequencies.indexOf(`${rate}s` as Frequency) !== -1) {
       rate = `1 ${rate}s`; // 'day' becomes '1 days'
     }