Add Forge::processIndexes() to create indexes on existing table

[sclubricants]

Closes #4814

This PR allows creating indexes on an existing table.

It is used following addKey(), addPrimaryKey(), addUniqueKey(), and addForeignKey() to add indexes to an existing table. It is used instead of or in place of createTable().

This is the last part of #6430

Fixes #6453

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[sclubricants]

@codeigniter4/database-team Please Review

[michalsn]

Some initial thoughts.

[kenjis]

Can you add a test case for without foreign key name?

[sclubricants]

I can, but I don't see it as necessary because _processForeignKeys() is called the same as with create table and there are tests that cover this already. I used names because it simplified the test. Your not going to get anymore code coverage with a test without names.

[kenjis]

As far as coverage is concerned, the coverage value we are getting now is line coverage, which means nothing more than knowing lines that are not covered.

Just because the coverage does not increase does not mean that the additional tests are useless or not. At the very least, branch coverage should be compared.

Looking at the implementation in this foreign key case, there is certainly no need to add it.
And as you say, testForeignKey() covers it.

[kenjis]

Anyway, I want to keep a test method short. If a test method is too long, it will be difficult to tell what is being tested. See #6676 (comment)

Other than that, I'm okay.

[michalsn]

Looks good to me. Thanks!

[kenjis]

Thank you!

[MGatner]

🕺🥳🚀