Modern C++ Programming with Test-Driven Development

2.15 Back on Track

When we started the work in this section, we were trying to write a test to handle the scenario where the second letter duplicates the first letter. That triggered us to make our algorithm case-insensitive. We can now return to our original goal and write this test:

TEST_F(SoundexEncoding, CombinesDuplicateCodesWhen2ndLetterDuplicates1st) {
   ASSERT_THAT(soundex.encode("Bbcd"), Eq("B230"));
}

Our solution involves a little bit of change to the overall policy embodied in ​encode​ . We pass the entire word to ​encodedDigits​ for encoding so that we can compare the encoding of the second letter to the first. We append only the tail of all encoded digits to the overall encoding.

In ​encodedDigits​ , we ...