How to load/remove namespaces in clojure during tests - clojure

Question

I'm working on a library that finds dependencies within the source tree during application startup and I'm trying to write an integration test to ensure it works. I've got fixture files in my test namespaces, and the test starts and succeeds just fine.
To be sure that the tests don't affect future runs, I added an "after" handler (in midje) that uses remove-ns to remove the test fixture namespaces.
On the next load, the tests fail because the namespaces are missing.
It seems as if remove-ns not only removes the namespace, it makes it impossible to use require to load it into the same running VM afterwards. I note that there is a "use with caution" note on remove-ns with no explanation.
I've verified that manually running require does not, indeed, seem to be able to re-load a namespace that has been removed:
user=>(test.util.fixtures.A/f)
{:item 1}
user=> (remove-ns 'test.util.fixtures.A)
#<Namespace test.util.fixtures.A>
user=> (test.util.fixtures.A/f)
ClassNotFoundException test.util.fixtures.A
user=> (require 'test.util.fixtures.A)
nil
user=> (test.util.fixtures.A/f)
ClassNotFoundException test.util.fixtures.A
Anyone understand why this is happening?

Answer 1

I traced through the source, and it ends up that require calls load-libs, which in turn calls load-lib, which in turn checks a global atom (the line is loaded (contains? #*loaded-libs* lib)).
Reading further, it seems that once something is loaded, you can specify the :reload option to the library loader. Now I remember seeing the :reload, so the solution was to put :reload in the require:
user=> (require 'test.util.fixtures.A :reload)
nil
user=> (test.util.fixtures.A/f)
{:item 1}