Unit test fails on JDK17 — What is the problem?
Recently, Android studio Flamingo 🦩 hit the stable channel. So I have updated the IDE and all works as expected.
Android studio Flamingo comes with default JDK set to
JDK17
- All works as expected until I run the unit tests for our project 💔
Our application support English and French. So we have unit tests for currency formatting to ensure it works as expected for both languages.
Tests for French currency formatted starts failing 😢 and we wonder why it starts falling on JDK17
From the failing tests, we found that there is an issue with the number separator🤯.
For the French locale, the number separator is changed to a narrow no-break space(NNBSP) U+202F
It wasn’t changed in JDK and it doesn’t just start with JDK17
Before JDK17, We are using JDK11. Until JDK12 there is no issue with the existing number separator(NBSP)
So what changes the number separator for French
In this bug, I found that it was introduced by the change in Unicode Common Locale Data Repository(CLDR) which is the upstream source of JDK
Fix
- If you are using a
hard-codednumber separator
// <= JDK12
private const val NBSP = "\u00A0"then change it to a new number separator
// Java 13 to 17
private const val NNBSP = "\u202F"Or
To make sure your tests are JDK-independent, use the following method
val separator = DecimalFormatSymbols.getInstance(Locale.FRENCH).groupingSeparatorFull sample code
/**
* @author Nav Singh
*
*/
class FrenchNumberSeparatorTest {
@Test
fun `when Locale is French then check number is properly formatted`() {
val formattedNumber = formatNumberToFrenchLocale(1000)
Assert.assertEquals("1${separator}000", formattedNumber)
}
@Test
fun `when number is formatted for French locale then check the number separator is valid`() {
val formatted = formatNumberToFrenchLocale(1000)
// Hard-coded separator - works only upto JDK12
// Assert.assertEquals(NBSP, formatted.substring(1, 2))
Assert.assertEquals(separator, formatted.substring(1, 2))
}
private fun formatNumberToFrenchLocale(number: Int): String {
val format = NumberFormat.getInstance(Locale.FRANCE)
return format.format(number.toLong())
}
companion object {
// Number separator in Java 8, 11 & 12.
private const val NBSP = "\u00A0"
// Number separator in Java 13 to 17.
private const val NNBSP = "\u202F"
// Get number separator and use it
val separator = DecimalFormatSymbols.getInstance(Locale.FRENCH).groupingSeparator.toString()
}
}
