Prevent task being scheduled again if .start() called while task is…

… running (Fixes #8)

changelog.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [1.6.1] - 04 Jul 2020
+### Fixed
+ - Fix bug when `task.start()` is called on a running task
+
 ## [1.6.0] - 17 Apr 2020
 ### Added
  - `CronosExpression` now has `warnings` property that lists possible errors in the expression. Currently supports detecting cases where increment value is larger than the valid (or supplied) range for a field

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cronosjs",
-  "version": "1.6.0",
+  "version": "1.6.1",
   "description": "A cron based task scheduler for node and the browser, with extended syntax and timezone support.",
   "keywords": [
     "cron",

src/scheduler.ts

@@ -102,17 +102,21 @@ export class CronosTask {
   }
 
   start() {
-    this._updateTimestamp()
-    addTask(this)
-    runScheduledTasks()
-    if (this.isRunning) this._emit('started')
+    if (!this.isRunning) {
+      this._updateTimestamp()
+      addTask(this)
+      runScheduledTasks()
+      if (this.isRunning) this._emit('started')
+    }
     return this
   }
 
   stop() {
-    this._timestamp = undefined
-    removeTask(this)
-    this._emit('stopped')
+    if (this.isRunning) {
+      this._timestamp = undefined
+      removeTask(this)
+      this._emit('stopped')
+    }
     return this
   }
 

tests/api.test.js

@@ -159,6 +159,60 @@ describe('Scheduling tests', () => {
     expect(task.isRunning).toEqual(false)
   })
 
+  test('Calling .start() while task running', () => {
+    const runCallback = jest.fn()
+    const startedCallback = jest.fn()
+    const stoppedCallback = jest.fn()
+
+    const fromDate = '2020-07-04T12:00:00Z'
+    mockDate(fromDate)
+
+    const task = new CronosTask(
+      CronosExpression.parse('0/5 * * * * *', {
+        timezone: 0
+      })
+    )
+
+    task
+      .on('started', startedCallback)
+      .on('run', runCallback)
+      .on('stopped', stoppedCallback)
+      .start()
+
+    for (let i = 1; i <= 6; i++) {
+      mockDate(task.nextRun)
+      jest.runOnlyPendingTimers()
+
+      expect(runCallback).toHaveBeenLastCalledWith(
+        1593864000000 + (i*5000)
+      )
+    }
+
+    expect(runCallback).toHaveBeenCalledTimes(6)
+
+    // second start call
+    task.start()
+
+    for (let i = 1; i <= 6; i++) {
+      mockDate(task.nextRun)
+      jest.runOnlyPendingTimers()
+
+      expect(runCallback).toHaveBeenLastCalledWith(
+        1593864030000 + (i*5000)
+      )
+    }
+
+    expect(runCallback).toHaveBeenCalledTimes(12)
+
+    expect(startedCallback).toHaveBeenCalledTimes(1)
+    expect(stoppedCallback).toHaveBeenCalledTimes(0)
+
+    task.stop()
+    task.stop()
+
+    expect(stoppedCallback).toHaveBeenCalledTimes(1)
+  })
+
   test('CronosTask with array of dates', () => {
     const startedCallback = jest.fn()
     const runCallback = jest.fn()