No, you're failing the second test in the "error handling" group:

it("error handling", () => {
  Test.assertEquals( encode( "abc", "x" ), null );
  Test.assertEquals( decode( "abc", [4] ), null );
  Test.assertEquals( decode( "abc", [-1,-2] ), null );
});

Not a kata issue.

JS - Fixed test error handling is broken when returning null

"abc" "x"

expected '' to equal null

Beautiful

You definetely can return a lambda function. Moreover, you can return lambda function from another lambda function.

can someone explain to me as to why you cant return a lambda function and give me some examples

Thanks, but it's not an assertion error. Looks like a bug in checking code:

java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 1
at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
at java.base/java.util.Objects.checkIndex(Objects.java:359)
at java.base/java.util.ArrayList.get(ArrayList.java:427)
at BurrowsWheeler.decode(BurrowsWheeler.java:37)

Also, I see something similar has been reported for Python and C++ some time ago.

Hi,

not an issue, a question.

something here might help

cheers

Java:
Attempt fails on assertEquals("Mellow Yellow", BurrowsWheeler.decode("ww MYeelllloo", 1)) with "java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 1" message. Same thing passes when hitting Test button.

Approved

Nice Kata

Very good challenge, took me quite a bit of brainpower to figure it out... hoping to encounter more like this.

Creating this solution was both enlightening and challenging, especially when it came to handling edge cases. One key complexity arose from dealing with scenarios where there was only one unique character in the input string. The original instructions left room for interpretation on this specific case, and my initial approach ended up returning an empty list, which didn't align with the test expectations.

if it overflows the flower will have many petals, an overflower if you will

there is an issue with PHP empty strings test
PHPUnit_Framework_Exception: Argument #2 (No Value) of PHPUnit_Framework_Assert::assertCount() must be a countable or traversable

If you do not want cheaters, you have to make it more challenging. ;)