Hi!

>The assertion has been made that typical applications have between 40%-50% of their code actually run during testing.
>

This is dependent on the kind of testing. We use 3 kinds of testing:
- QA testing by operator person and qualified QA tester
- Code review for code quality and standards following
- Developer's testing during development.

This guarantees at least 90% of code is tested in our applications.

>I am curious to see what percentage of code you test (actually run during development/unit test/system testing) for:
>
>1) The development of a system from scratch.
>

Already answered :)

>
>2) The development of a new/replacement system but using code parts (including classes, functions, etc.) from existing and well-running systems.
>

Developer's testing only for fixing existing things. When there are a lot of changes gathered, QA testing and code review. So, for small changes it is around 80%, because hard to miss something in small changes. For larger number of changes and larger changes, we use the same procedure as for 1

>
>3) Developing revisions to an existing application.
>

The same as 1, but for changed parts only. Revisions go as separate projects with certain time added because code revision of older application. We make complete testing of older modules too, but this is optional.

>
>Thanks for your reply.