Run tests from Clojure Repl and Leiningen

Start a REPL with lein repl, then use require

(require '[clojure.test :refer [run-tests]])
(require 'your-ns.example-test :reload-all)
(run-tests 'your-ns.example-test)

I prefer to stay in the user namespace, as opposed to changing it with in-ns as mentioned by another answer. Instead, pass the namespace as an argument to run-tests (as shown above).

I'd also recommend staying away from (use 'clojure.test); that is why I suggested (require '[clojure.test :refer [run-tests]]) above. For more background, read http://dev.clojure.org/jira/browse/CLJ-879

In your example above the repl is in the wrong namespace. It may work better if you switch the repl to the core_test namespace. and then run (run-tests).

(in-ns 'first-project.core-test)
(run-tests)

Another fun way of developing tests is to just run them from the REPL until they work, because tests are normal functions with some extra metadata.

(in-ns 'first-project.core-test)
(my-test)

Remember you have to load the file in addition to calling in-ns Let's say your test file is tests/first_project/core_test.clj, then you will need to call

(load "tests/first_project/core_test")
(in-ns 'first-project.core-test)
(my-test)

Keep in mind that _ in the file system becomes - in the namespace and / becomes ..

To recap:

Way of require

Full qualification of functions is only needed if you issued an in-ns earlier. Then do:

(clojure.core/require '[clojure.core :refer [require]]
                      '[clojure.test :refer [run-tests]]
                      '[clojure.repl :refer [dir]])

---

; Load whatever is in namespace "foo.bar-test" and reload everything
; if `:reload-all` has been additionally given

(require 'foo.bar-test :reload-all) 
;=> nil

; List your tests for good measure (Note: don't quote the namespace symbol!)

(dir foo.bar-test)
;=> t-math
;=> t-arith
;=> t-exponential
;=> nil 

; Check meta-information on a test to verify selector for example 

(meta #'foo.bar-test/t-math)
;=> {:basic-math true, :test #object[foo.bar_tes...

; `run-tests` will probably run nothing because the current namespace
; doesn't contain any tests, unless you have changed it with "in-ns"

(run-tests) 
;=> Ran 0 tests containing 0 assertions.

; run tests by giving namespace explicitly instead

(run-tests 'foo.bar-test) 
;=> Ran 3 tests containing 29 assertions.