feat: add check for non-integer numbers (#291)

Author: Airfooox

src/helper.ts

@@ -52,6 +52,11 @@ const checkSingleElementWithinLimits = (
     return err(`Element '${element} of ${cronFieldType} field is invalid.`)
   }
 
+  // check if integer and not a decimal
+  if (number % 1 !== 0) {
+    return err(`Element '${element} of ${cronFieldType} field is not an integer.`)
+  }
+
   const { lowerLimit } = options[cronFieldType]
   const { upperLimit } = options[cronFieldType]
   if (lowerLimit && number < lowerLimit) {

src/index.test.ts

@@ -114,6 +114,13 @@ describe('Test cron validation', () => {
     expect(cron('1,2,3 4,5,6 1 1 1').isValid()).toBeTruthy()
 
     expect(cron('01,02,03 04,05,06 01 01 01').isValid()).toBeTruthy()
+
+    expect(cron('1 1 1 1 1').isValid()).toBeTruthy()
+    expect(cron('0.1 1 1 1 1').isValid()).toBeFalsy()
+    expect(cron('1 0.1 1 1 1').isValid()).toBeFalsy()
+    expect(cron('1 1 0.1 1 1').isValid()).toBeFalsy()
+    expect(cron('1 1 1 0.1 1').isValid()).toBeFalsy()
+    expect(cron('1 1 1 1 0.1').isValid()).toBeFalsy()
   })
 
   it('Test cron field assignment', () => {