CODEWITHSUNDEEP
c++unit-testing
Peter
Peter

Reputation: 1471

C++ Unit Test with Diff on Files

Is there any library that allows you to diff files in C++ unit tests? Ideally this would work with Boost Unit tests.

I was thinking of a function along the lines of:

CHECK_FILES_EQUAL('output.txt', 'reference.txt');

Which would then fail the test if the files were equal (possibly showing the line that it failed on).

Thanks

Upvotes: 6

Views: 1746

Answers (3)

Marek R
Marek R

Reputation: 37707

Well behaving unit test should not write anything in filesystem. If you are using STL streams then you should use abstraction std::ostream and then when testing feed std::ostringstream in place of this abstraction.

Just read whole file into a string and compare it. GTest will notice large strings and will print proper diff.

Some demo

Upvotes: 0

0RR
0RR

Reputation: 1603

You can use ApprovalTests to create tests which compare some output file to some approved output. If they differ it can display it in a diff tool e.g. kdiff, and you can choose to accept the changes and update your approved output or reject the test.

Upvotes: 0

Liosan
Liosan

Reputation: 7940

I assume you want something more intelligent that just checking if the files equal byte-by-byte. I would use google-diff-match-patch, a powerful library which can (among other functionality) calculate a diff between two files. A C++ implementation is available, along with other languages. You'll need to handle file IO yourself, though.

Upvotes: 2

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