Make *test-object* in test-engine a parameter

[dbp]

This looks like something that could be a parameter:

htdp/htdp-lib/test-engine/test-engine.rkt

Line 146 in 73ec2b9

(define *test-object* (empty-test-object))

And if it were also exposed as such, it would be helpful.

As one example: I would like to be able to dynamically load a module and not have it register any of its tests (as the only reason I'm loading it is to grab a definition from its namespace). That would be easy to do if it were a parameter, but seems quite hard currently.

[mfelleisen]

If the loaded file is under your control, organize it differently: Modular Programming

[dbp]

@mfelleisen it's (by design) not. The application is: https://github.com/dbp/htdp-examplar -- I am taking student submissions, swapping their implementations with reference good/bad ones, putting their implementations into good test suites, etc. There are enough knobs on test-engine that it works, but it's a little clumsy (I pass around test suites, initialialize-test-object! very frequently, etc).

[mfelleisen]

OK, let's see what @mikesperber says.

[mikesperber]

I am sympathetic to solving your problem, but am not sure a parameter is a good fit for your use case. @dbp could you elaborate where the use case is coming from, and possible others?

[dbp]

@mikesperber All my uses are actually in the code linked above. You can see, e.g., here: https://github.com/dbp/htdp-examplar/blob/297e0776c25dbd13af8605eb69cd2e799b589c0a/main.rkt#L60 -- I have copied the tests earlier (by initializing, loading the file, and then grabbing what is returned by current-test-object), and now am running them, one at a time, by initializing, adding, running. The code works, but it feels a bit clumsy (or if not clumsy, very imperative).

Part of that is that I can only modify the current set of tests by either initializing or adding a single test, but another part is that getting tests from a file involves loading the file, which then mutates global state (and only happens the first time the file is loaded).

[mikesperber]

@dbp Ah, I see. Thanks! Turning this into a parameter doesn't really change the imperativeness, I feel, and complicates the semantics wrt. threads.

So I'd rather provide something more high level.

Would a dynamic form where you do:

(call-with-test-engine-disabled
  (lambda ()
    <your code>))

also work for you?