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.