Testing LZ77 string index out of range

[makavelj]

Sometimes the test for LZ77 fails with the error message:

File "test_lempelziv.py", line 25, in
test_77(string)
File "test_lempelziv.py", line 17, in test_77
enc = lz.lz77_encoding(string)
File "/home/janosch/Compression/compress/lz778.py", line 24, in lz77_encoding
pattern += omega[i]
IndexError: string index out of range

Needs to check for which strings the index goes out of range.