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Add support for Clojure and clojure.test to Concordion, a Specification By Example tool.

With Concordion, you can write high-level specification of features in Markdown and document them with examples. Hidden instrumentation (in the form of magic links) binds the examples to functions in your Fixture classes making it possible to verify them against the code. When you run your test runner, Concordion does generate HTML files incorporating results of the passed or failed examples/tests.


Docs: cljdoc badge


Add a dependency on this project (copy the latest dependency specification for Lein/Boot/deps.edn/Gradle/Maven from Clojars):

Clojars Project

(Depending on your build tool, you might also need to add an explicit dependency on org.concordion/concordion, see our project.clj.)

and configure your tests so that the test namespaces are compiled (which is necessary since we need to generate fixture classes). With lein:

;; project.clj
(defproject ...
  :profiles {:test {:aot [mypapp.core-test] }} ;; Or a RegExp for all fixture test namespaces


Given the Concordion specification <class path>/math/ containing:

Adding [1](- "#n1") and [3](- "#n2") yields [4](- "?=add(#n1, #n2)").

you need to implement the function in a test namespace and create the fixture for it:

(ns mypapp.core-test
      [clj-concordion.core :as conc]))

;; The arguments and return values must by type-hinted using one of the types
;; supported by Concordion: Integer, boolean, or (default) String. If no type 
;; hint is provided at some place, String is assumed.
(defn ^Integer add [^Integer n1, ^Integer n2]
  (int (+ n1 n2)))

;; Create the fixture class and clojure.test test, passing it the function(s)
;; Notice that the name of the class corresponds to the path to the specification
;; .md (plus the optional "Fixture")
;; You can have one or more fixtures in one namespace and the name of the 
;; namespace plays no role
(conc/deffixture "math.AdditionFixture" [add])

And run it:

$ lein with-profile auto test
Compiling mypapp.core-test

lein test mypapp.core-test

Successes: 1, Failures: 0

Ran 1 tests containing 0 assertions.
0 failures, 0 errors.


Notice that deffixture takes a third parameter, a map of options - see the spec for valid keys and FixtureDeclarations, ConcordionOptions and Concordion docs for their meaning.

Setup & tear-down functions

The opts argument do deffixture can also contain setup/tear-down functions run at different points of the lifecycle:

  {::cc/before-suite   #(println "AdditionFixture: I run before each Suite")
   ::cc/before-spec    #(println "AdditionFixture: I run before each Spec")
   ::cc/before-example #(println "AdditionFixture: I run before each example")
   ::cc/after-example  #(println "AdditionFixture: I run after each example")
   ::cc/after-spec     #(println "AdditionFixture: I run after each Spec")
   ::cc/after-suite    #(println "AdditionFixture: I run after each Suite")})

REPL development

To be able to run tests repeatedly from the REPL, you need to reset the previously cached results:


Additional resources


  1. You need to run lein clean if you change/rename the fixture so that the class will be recompiled
  2. We use clojure.test underneath so you must follow its naming syntax for test namespaces, i.e. for example <name>-test


Alpha. Core features supported but there are certainly many rough corners and lurking bugs.


  • You cannot and must not use the example command (i.e. # \[Your heading](- "example name")) - if you do, your asserts will be ignored. (Until we fix #2)
  • concordion:set is not supported as it goes against our functional thinking; we can add it if there is a good use case and demand




  • The we use is deprecated, we should use (String example, Fixture fixture) instead
  • Support also ^long, not just int (converting to int underneath)
  • In the generated test, add an assertion to check that output from concordion was OK so that also clojure.test output shows correctly failed/passed.
  • Re-run tests also when the .md files changes - add the resources/ to the watch path


Concordion uses OGNL to map function calls and property access in the specification to the fixture class, using presumably reflection, requiring that the fixture class has a method with a corresponding name and compatible params.

Unless we decide to replace Concordion's default Evaluator with something more Clojure-friendly, we need to use gen-class to create a class and object matching OGNL's / Concordion's expectations.

The current implementation is based on JUnit3 ConcordionTestCase.

There's 2 places where the test runner is called:

Directly when invoking a test - eg. the JUnit4 ConcordionRunner, the JUnit3 ConcordionTestCase. These call FixtureRunner which calls ConcordionBuilder. You're likely to want to create something similar to ConcordionTestCase and FixtureRunner, then reuse ConcordionBuilder - eg, see Mark Derricutt's basic TestNG runner. This was created way back for Concordion 1.3.1 - you'll need to implement the Fixture and FixtureDeclarations interfaces from Concordion 2.0.0 onwards.

Indirectly, from a Concordion Suite, when the concordion:run command is encountered in a specification, spawning a new test within a test. If you want to support the concordion:run command, this is where the Runner / DefaultConcordionRunner comes in. By default ConcordionBuilder plugs in a SystemPropertiesRunnerFactory which lets you override the Runner with a system property. If this doesn't suit, we could open up withRunnerFactory as an extension method - rather than overriding RunStrategy which is designed to cater for different strategies for invoking the Runner.



# Ensure credentials unlocked
gpg --quiet --batch --decrypt ~/.lein/credentials.clj.gpg
# Deploy
lein deploy clojars



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