lein repl results in java.lang.AssertionError (transport-fn)

will help you Try lein trampoline run, it works.
The following is from leiningen FAQ:

Hope this helps One thing you could do to get it to work would be to change core.clj to:

(ns my-project.core
  (:gen-class))

(defn hello []
  (println "Hello world!"))

(defn -main []
  (hello))

(defproject my-project "1.0.0-SNAPSHOT"
  :description "FIXME: write description"
  :dependencies [[org.clojure/clojure "1.3.0"]]
  :main my-project.core)

this will help In a default lein new project you need to require the namespaces you wish to use explicitly -- (require 'my-lib.core). in-ns simply creates a new empty namespace of the given name if it doesn't already exist, it doesn't load any code from the classpath.
App projects do this automatically and switch to the main namespace in the REPL task, because they have a :main foo.core entry in their project.clj by default. It's possible to do it for a library, but you shouldn't -- as a side effect, it causes AOT compilation of the main namespace, which is generally undesirable.

wish help you to fix your issue It is likely the errors are not in the order you expect them.
Further it would be better to split the test so that each validation is verified individually. In other words have ...WithMissingLastName, ...WithMissingLogin, ...WithMissingEmailAdress, ...WithMissingRole tests.

will be helpful for those in need There is a github issue for cider describing the problem and providing a workaround for this issue. but for some reason google did not get me there. google is off today
this is the issue: