import assert from 'assert' ; import differenceInMilliseconds from '.' ; describe ( 'differenceInMilliseconds' , ( ) => { it ( 'returns the number of milliseconds between the given dates' , ( ) => { const result = differenceInMilliseconds ( new Date ( 2014 , 6 , 2 , 12 , 30 , 20 , 700 ) , new Date ( 2014 , 6 , 2 , 12 , 30 , 20 , 600 ) ) ; assert ( result === 100 ) ; } ) ; it ( 'returns a negative number if the time value of the first date is smaller' , ( ) => { const result = differenceInMilliseconds ( new Date ( 2014 , 6 , 2 , 12 , 30 , 20 , 600 ) , new Date ( 2014 , 6 , 2 , 12 , 30 , 20 , 700 ) ) ; assert ( result === - 100 ) ; } ) ; it ( 'accepts timestamps' , ( ) => { const result = differenceInMilliseconds ( new Date ( 2014 , 8 , 5 , 18 , 30 , 45 , 500 ) . getTime ( ) , new Date ( 2014 , 8 , 5 , 18 , 30 , 45 , 500 ) . getTime ( ) ) ; assert ( result === 0 ) ; } ) ; it ( 'does not return -0 when the given dates are the same' , ( ) => { function isNegativeZero ( x ) { return x === 0 && 1 / x < 0 ; } const result = differenceInMilliseconds ( new Date ( 2014 , 8 , 5 , 0 , 0 ) , new Date ( 2014 , 8 , 5 , 0 , 0 ) ) ; const resultIsNegative = isNegativeZero ( result ) ; assert ( resultIsNegative === false ) ; } ) ; it ( 'returns NaN if the first date is `Invalid Date`' , ( ) => { const result = differenceInMilliseconds ( new Date ( NaN ) , new Date ( 2017 , 0 , 1 ) ) ; assert ( isNaN ( result ) ) ; } ) ; it ( 'returns NaN if the second date is `Invalid Date`' , ( ) => { const result = differenceInMilliseconds ( new Date ( 2017 , 0 , 1 ) , new Date ( NaN ) ) ; assert ( isNaN ( result ) ) ; } ) ; it ( 'returns NaN if the both dates are `Invalid Date`' , ( ) => { const result = differenceInMilliseconds ( new Date ( NaN ) , new Date ( NaN ) ) ; assert ( isNaN ( result ) ) ; } ) ; it ( 'throws TypeError exception if passed less than 2 arguments' , ( ) => { assert . throws ( differenceInMilliseconds . bind ( null ) , TypeError ) ; assert . throws ( differenceInMilliseconds . bind ( null , 1 ) , TypeError ) ; } ) ; } ) ;