For some meaning of "contain things it shouldn't":
Given that the base image we started working with didn't "contain things it shouldn't" why could we not be completely sure that base image + source code fileIn didn't "contain things it shouldn't" ?
First, as most other companies using ST we were not working on the original image, but on a company-specific one that had been in use for a long time and contained a lot of company-specific stuff. On the other hand, there were also things in the original images of the commercial STs that one would or should not ship with the product.
Not sure what you're up to; there were things in the image nobody had the source code (or the current version) anymore, but even with the source code it was a nightmare; it would undoubtedly have been less bad had I then had tools like I recently built for ST80 and the knowledge gained with them.
That was my personal impression as a trained engineer based on relevant experience, not a condemnation; I on the other hand find it annoying when some people glorify Smalltalk in retroperspective and attribute to it any great qualities without evidence and against better knowledge; nevertheless, the technology is impressive in a historical context and worth studying (but I still wouldn't use it for industrial projects anymore and would also not like to tempt other people).
We tested until our ears fell off; in particular, we had also to test all the stuff that the compiler (or linker) would otherwise have told us in a statically typed language; there was no other way; might explain why I directly switched to Ada for some time after ST; but how do you test for dead code (i.e. things in the image not used but still there for some reason)? It is not for nothing that people speak of a "Big ball of Mud" in the context of image based languages.
And did you discover stuff that was reported to have been removed but your tests showed was not removed?
In other words, examples where "trust it" would be a demonstrable mistake.
> It is not for nothing that people speak of a "Big ball of Mud" in the context of image based languages.
What process was used to manage source code?
"At the outset of a project involving two or more programmers: Do assign a member of the team to be the version manager. … The responsibilities of the version manager consist of collecting and cataloging code files submitted by all members of the team, periodically building a new system image incorporating all submitted code files, and releasing the image for use by the team. The version manager stores the current release and all code files for that release in a central place, allowing team members read access, and disallowing write access for anyone except the version manager." (page 500)
1984 "Smalltalk-80 The Interactive Programming Environment"
Working with a team on industrial projects is another thing than quoting from a book that - albeit somewhat naively - even talks about configuration management in one section.
Why should I answer your questions when you only question everything I say anyway and do not answer my questions?
If you understood why the absence of dead code cannot be detected by testing, and that there is no algorithm that can identify all dead code reliably and in finite time in a dynamic language like Smalltalk, your questions and implications would become pointless, since you then would understand why you never can be completely sure indeed; and that's all there is to it.
Given that the base image we started working with didn't "contain things it shouldn't" why could we not be completely sure that base image + source code fileIn didn't "contain things it shouldn't" ?