Testing with Midje
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The document provides a comprehensive overview of testing in Clojure using Midje, highlighting its non-lispy expectation syntax and various testing constructs such as facts, checkables, and checkers. It includes examples of stubbing, mocking, and project setup necessary to effectively implement testing in Clojure. Additionally, it outlines how to assert conditions and check for function behaviors within the testing framework.
![Why Midje?
Non-lispy expectation syntax
(conj [1 2] 3) => [1 2 3]
vs
(is (= [1 2 3] (conj [1 2] 3)))](https://image.slidesharecdn.com/testingwithmidje-150124082442-conversion-gate01/85/Testing-with-Midje-7-320.jpg)
![(defn each-element-is-one-of [expected-elements]
(fn [actual]
(every? (set expected-elements) actual)))
(fact "each element is one of 1-10"
'(1 2 3 4 5 6) => (each-element-is-one-of (range 1 11)))
Checkers - own checkers](https://image.slidesharecdn.com/testingwithmidje-150124082442-conversion-gate01/85/Testing-with-Midje-21-320.jpg)
![(defn find-user [username]
;; Code that finds the user in the database
)
(defn authenticate [username password]
(let [user (find-user username)]
(if (= (:password user) password)
user)))
(fact "it authenticates a user with a valid password"
(authenticate "the fly" "12345") => truthy
(provided
(find-user "the fly") =>
{:name "the fly" :password "12345"}))
Prerequisites - Stub](https://image.slidesharecdn.com/testingwithmidje-150124082442-conversion-gate01/85/Testing-with-Midje-23-320.jpg)
![Project setup
~/.lein/profiles.clj
{:user {:plugins [[lein-midje "3.1.3"]]}}](https://image.slidesharecdn.com/testingwithmidje-150124082442-conversion-gate01/85/Testing-with-Midje-25-320.jpg)
Testing with Midje
- 1. Testing with Midje Tobias Bayer :clojureD 2015, Berlin
- 3. Midge Midje
- 7. Why Midje? Non-lispy expectation syntax (conj [1 2] 3) => [1 2 3] vs (is (= [1 2 3] (conj [1 2] 3)))
- 8. Why Midje? Helpers and tools Checking functions for expectations Simple stubbing and mocking Auto-testing ...
- 10. Midje equivalent of a test Facts
- 11. (facts "about +" (fact "1 plus 2 equals 3" (+ 1 2) => 3) (fact (+ -1 -1) => -2)) Facts
- 12. (future-fact "it returns fancy" (fancy-function) => "fancy") ;; => WORK TO DO Facts
- 13. (facts "about +" (fact "1 plus 2 equals 3" (+ 1 2) => 3)) Checkables
- 14. (facts "about +" (fact "1 plus 2 equals 3" (+ 1 2) => 3)) Checkables
- 15. (facts "about +" (fact (+ 1 1) =not=> 3)) Checkables
- 16. Can be used instead of values on the right side of a checkable Checkers
- 17. (facts "about my list" (fact "it contains the value 5" '(1 2 3 4 5 6) => (contains 5)) (fact "it contains the values 2 and 3" '(1 2 3 4 5 6) => (contains 2 3)) (fact "it contains an odd number followed by an even number" '(1 2 3 4 5 6) => (contains odd? even?))) Checkers - contains
- 18. (facts "about my map" (fact "the value of x is 1" {:x 1 :y 2} => (contains {:x 1})) (fact "the value of y is even" {:x 1 :y 2} => (contains {:y even?}))) Checkers - contains
- 19. (throwing-function) => (throws Exception) (throwing-function) => (throws Exception "foo") (throwing-function) => (throws Exception #"(foo|bar)") Checkers - throws
- 20. (fact "insert-value has a side effect" (reset-values) => irrelevant (exists-value? "foo") => falsey (insert-value "foo") => irrelevant (exists-value? "foo") => truthy) Checkers - anything/irrelevant
- 21. (defn each-element-is-one-of [expected-elements] (fn [actual] (every? (set expected-elements) actual))) (fact "each element is one of 1-10" '(1 2 3 4 5 6) => (each-element-is-one-of (range 1 11))) Checkers - own checkers
- 22. OO-world: stubbing and mocking Prerequisites
- 23. (defn find-user [username] ;; Code that finds the user in the database ) (defn authenticate [username password] (let [user (find-user username)] (if (= (:password user) password) user))) (fact "it authenticates a user with a valid password" (authenticate "the fly" "12345") => truthy (provided (find-user "the fly") => {:name "the fly" :password "12345"})) Prerequisites - Stub
- 24. (fact "it calls the second function 5 times with argument 'foo'" (first-function "foo") => irrelevant (provided (second-function "foo") => irrelevant :times 5)) (fact "it never calls the third function with any argument" (first-function "foo") => irrelevant (provided (third-function anything) => irrelevant :times 0)) Prerequisites - Mock
- 25. Project setup ~/.lein/profiles.clj {:user {:plugins [[lein-midje "3.1.3"]]}}
- 26. Project setup lein new midje midje-intro
- 27. Project setup lein new midje midje-intro
- 28. Project setup lein new midje midje-intro
- 29. DEMO
Editor's Notes
- #3: Has anyone ever been to the Scottish Highlands?
- #4: Fortunately, you only have to replace one letter to improve things a lot. ;)
- #5: My name is Tobias Bayer… I work as a developer for inovex inovex: medium sized Software Company from Karlsruhe with offices in Cologne and Munich (where I work) By the way, I’ll push the sample code I’ll be showing here to GitHub after the talk...
- #6: These are some of the Midje examples I’ll walk you through in the talk… You can see some of the major building blocks of a Midje test… Name some of the building blocks: “facts” “=> arrow” “provided” live demo afterwards
- #7: But, first things first. Why should you use Midje for testing Clojure apps? Or why do I prefer to use Midje?
- #8: “non-lispy” at a Clojure conference more readable in tests, first execution _then_ expectation, grew up reading from left to right i also think it was done by mistake in JUnit when they put the expectation before the execution in the assert-methods :)
- #14: A checkable is the heart of a fact Here you execute your function under test with its arguments and define your expectation
- #15: Consists of three parts: left hand side, right hand side and arrow Function under test, arrow, expectation
- #16: =not=> arrow Other arrows available
- #17: ca. at 10 minutes
- #21: anything/irrelevant -> prerequisites, side effects truthy/falsey -> nil/false not nil/true