On Fri, Sep 16, 2011 at 4:28 PM, Chris Perkins <chrisperkin...@gmail.com>wrote:
> On Friday, September 16, 2011 3:12:49 PM UTC-4, Brian Hurt wrote: >> >> >> >> On Thu, Sep 15, 2011 at 6:42 AM, Chris Perkins <chrispe...@gmail.com>wrote: >> >>> On Wednesday, September 14, 2011 11:19:13 AM UTC-4, Brian Hurt wrote: >>>> >>>> Say I have two name spaces, A and B, with A depending on B. I want to >>>> test namespace A, replacing module B with a mock B for testing purposes- >>>> preferably without having to load B at all (B sucks in a bunch of stuff, >>>> like dependencies on databases and external web sites and etc. that I don't >>>> want to deal with in testing). What is the easy, clojure-approved, >>>> mechanism for doing this? I tried: >>>> >>>> How *should* I structure this code for testing? I was assuming the >> natural way to do this is to make A, B, and C separate name spaces but maybe >> this is wrong. >> >> The problem isn't just *writing* the code- I need to be able to change >> this code later, and have some assurance it still works. So "load it up >> into a repl and play with it" isn't a viable solution. >> >> Or is clojure code just not testable/maintainable? >> >> Brian >> >> > I don't have a detailed answer because I haven't done much mocking myself, > but I'm confident that it's possible. The reason for my confidence is that > references from one namespace to another live in Vars, which are mutable. > > Here's a very simple example: I made a namespace "a" containing a function > "a-fn", which just calls b-fn in namespace b. Then I created a "mock-b" that > defines a different b-fn. > > user=> (require 'a) > nil > user=> (a/a-fn) > "real b" > user=> (require 'mock-b) > nil > user=> (alter-var-root #'b/b-fn (constantly mock-b/b-fn)) > #<mock_b$b_fn mock_b$b_fn@1e1be92> > user=> (a/a-fn) > "mock b" > > Note that the behavior of a-fn has been altered at runtime. I can imagine > a mocking utility that, given a namespace (eg: "b"), and a mock namespace > (eg: "mock-b"), would go through the vars in mock-b and call alter-var-root > on all the matching vars in b before calling a test suite. In fact, I > wouldn't be surprised at all to find this on github somewhere. > > Not much detail there, but I hope this helps somewhat. > > > For the record, this is exactly what I'm doing- I'm just kind of surprised I have to actually create this infrastructure. Brian -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
