java-diff-utils is a library for comparing texts: computing diffs, applying patches, generating unified diffs,...

https://code.google.com/p/java-diff-utils/

Issue 10: https://code.google.com/p/java-diff-utils/issues/detail?id=10&can=1

Problem:
We have 1 original text file and a patch file for it, when apply patch for the original text, we get an exception with this stack trace:


You can get the input files in the above link of this issue

Result from Ziyuan:


The predicate is output to the users:

line.isEmpty == false (difflib.DiffUtils:137)

Explanation for the bug:
In the function DiffUtils.parseUnifiedDiff(List diff), when parsing the patch file, in case the line is empty, it was not added to rawChunk. As a result, the patch and the original text have a different number of lines, which later causes the exception.
This is the fix for the bug:

We feed the passed test cases from Ziyuan to Daikon. After a while, Daikon creates a lot of invariants (file). We check the invariants inside the function parseUnifiedDiff(). However, no useful invariants has been found.