Porting Java tests to C++

In this blog post, I discuss porting Java tests from Java to C++. We have many Java tests, and porting them to C++ is beneficial for LibreOffice. Here I discuss why, and how.

Why Porting Java Tests?

In the past, Java was used extensively in LibreOffice, and many tests where written in Java. They consist of various tests, including JUnit.

Searching for junit in LibreOffice source code gives many results: (Note that this is not the number of tests)

$ git grep -i junit | wc -l

901

Although these tests are useful, they have drawbacks:

1. They are slower than C++ CppUnitTests

2. They are outside process, which is creates them even more slower, and harder to debug

Porting these tests to C++ can make them faster, more reliable, and easier to debug. Let’s see how we can do it.

Start from Examples

The best way to find out how to do porting is to look into the previous examples. This issue is around porting Java API tests to C++:

• tdf#45904 – Move Java based API tests to C++

There are many commits in the above page, which can be an interesting way to learn how to do that. For example, consider this commit:

• tdf#45904 Move Java _XSheetCellRanges tests to C++

In the above commit, Jens has ported qadevOOo/tests/java/ifc/sheet/_XSheetCellRanges.java test to C++ test test/source/sheet/xsheetcellranges.cxx.

I can summarize the changes in this way:

1. An equivalent C++ file, in test/ folder

2. Removal of Java file from qadevOOo/.

3. The Makefiles in test/ and qadevOOo/ folders should reflect the removal of Java test, and addition of C++ test.

4. Some Java tests are adjusted to reflect the deletion of the old Java test.

5. Some C++ tests are adjusted to reflect the addition of new C++ test.

Final Words

To be able to port a test, one should be able to understand the old test. Reading the code is the best way that one can achieve this purpose. By looking into similar ports, you can gain a better understanding of what to do. In Bugzilla page for tdf#45904, you may find similar ports.