feat: Add support for conditional jobs declaration

By ignoring falsy values in the jobs array.

README.md

@@ -207,6 +207,26 @@ if (process.env.INSTANCE_NUMBER === 0) {
 }
 ```
 
+## Conditionally running jobs
+
+You may want to run certain jobs in development only, or under other conditions.
+
+`fastify-cron` will ignore any falsy values in the `jobs` array, so you can do:
+
+```ts
+server.register(fastifyCron, {
+  jobs: [
+    process.env.ENABLE_DEV_JOB === 'true' && {
+      name: 'devJob',
+      cronTime: '* * * * *',
+      onTick: server => {
+        // ...
+      }
+    }
+  ]
+})
+```
+
 ## Compatibility Notes
 
 Some compatibility issues may arise with the [`cron` API](https://github.com/kelektiv/node-cron#api).

src/index.test.ts

@@ -112,4 +112,21 @@ describe('Creating jobs manually after registration', () => {
     expect(job).toBeDefined()
     expect(job!.running).toBeFalsy()
   })
+
+  test('falsy values are ignored in the jobs array', async () => {
+    const server = Fastify({ logger: false })
+    const spy = jest.fn()
+    await server.register(fastifyCron, {
+      jobs: [
+        false && {
+          name: 'foo',
+          cronTime: '* * * * *',
+          onTick: spy
+        }
+      ]
+    })
+    await server.ready()
+    const job = server.cron.getJobByName('foo')
+    expect(job).toBeUndefined()
+  })
 })

src/index.ts

@@ -27,8 +27,10 @@ export interface CronDecorator {
   stopAllJobs: () => void
 }
 
+export type FalsyValue = undefined | null | false
+
 export interface Config {
-  jobs?: Params[]
+  jobs?: (Params | FalsyValue)[]
 }
 
 const plugin: FastifyPluginAsync<Config> = async function fastifyCronPlugin(
@@ -66,7 +68,9 @@ const plugin: FastifyPluginAsync<Config> = async function fastifyCronPlugin(
     }
   }
   for (const params of opts.jobs || []) {
-    decorator.createJob(params)
+    if (params) {
+      decorator.createJob(params)
+    }
   }
 
   server.decorate('cron', decorator)