Krakow Decompressed

(or 'What I learned @EuroClojure 2014')

@kevin_noonan

Clojure Ireland

3rd Sept 2014, Dublin

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Part 1. Swagger & Prismatic Schema

To document & validate an API developed in Clojure

Prismatic Schema

https://github.com/Prismatic/schema

	  (:require [schema.core :as s])

Define a data-type with Schema

(def Data
  "A schema for a nested data type"
    {:a {:b s/Str
         :c s/Int}
	 :d [{:e s/Keyword
	      :f [s/Num]}]})

Test a sample of valid data

(s/validate
  Data
  {:a {:b "abc"
       :c 123}
   :d [{:e :bc
        :f [12.2 13 100]}
       {:e :bc
        :f [-1]}]})
;; Success!

Pass invalid data to Schema

(s/validate
  Data
  {:a {:b 123
       :c "ABC"}})
;; Exception -- Value does not match schema:
;;  {:a {:b (not (instance? java.lang.String 123)),
;;       :c (not (integer? "ABC"))},
;;   :d missing-required-key}

Compojure-api

https://github.com/metosin/compojure-api

(ns compojure.api.examples.handler
  (:require [compojure.api.sweet :refer :all]
;; ... & other libraries...
))

Integrates several packages

Compojure & Ring (basic web-stack)

Prismatic Schema (to validate data-types)

ring-swagger (generate JSON to document an API)

Define data-type & set up routing...

(s/defschema Total {:total Long})
;;
(defapi app
  (swagger-ui)
  (swagger-docs
    :title "Sample api")
  (swaggered "thingie"
    :description "There be thingies"
    (context "/api" [] 
;; continued on next slide

Define an API endpoint...

(GET* "/plus" []
  :return       Total
  :query-params [x :- Long y :- Long]
  :summary      "x+y with query-parameters."
  (ok {:total (+ x y)}))
;; ...several other API calls omitted.
)))

Swagger UI

JavaScript to consume JSON to document an API.

https://github.com/wordnik/swagger-ui

Available for many languages (not just Clojure)

Alternatives to Compojure-api

Octohipster (based on Liberator)

Prismatic Fnhouse (alpha)

Alternative to ring-swagger

https://github.com/narkisr/swag

Part 1 was inspired by...

"Schema & Swagger: making your Clojure web APIs more awesome", by Tommi Reiman.

http://www.slideshare.net/metosin/euroclojure2014-schema-swagger-making-your-clojure-web-apis-more-awesome

Part 2. JVM breakglass

A dynamic backdoor to diagnose a static (Java) system.

JVM- breakglass

https://github.com/matlux/jvm-breakglass

breakglass demo

One-page tutorial-style guide to using JVM Breakglass

https://github.com/matlux/jvm-breakglass/blob/master/bootloader/src/main/clojure/cl_java_introspector/examples.clj

Part 2 was inspired by...

"JVM Break Glass - Using a Clojure REPL to troubleshoot live Java/JVM processes", by Mathieu Gauthron

http://slides-euroclojure2014.matlux.net

Part 3. "Generative testing" with test.check

Make assertions about your code

Let the test-library bombard your functions with generated test-data.

test.check reimplements QuickCheck (available for Erlang, Haskell)

https://github.com/clojure/test.check

(require '[clojure.test.check :as tc])

Generators

generate random data, of a given type; starts off simply

;;
(require '[clojure.test.check.generators :as gen])

Properties

for making general statements about data

;;
(require '[clojure.test.check.properties :as prop])

Test the sort function

(def prop-sorted-first-less-than-last
  (prop/for-all [v (gen/not-empty (gen/vector gen/int))]
    (let [s (sort v)]
      (< (first s) (last s)))))

Run tests against the sort function

;;
(tc/quick-check 100 prop-sorted-first-less-than-last)
;; {:result false, :failing-size 0, :num-tests 1, :fail [[3]],
;; :shrunk {:total-nodes-visited 5, :depth 2, :result false,
;;         :smallest [[0]]}}

Example of a bad property

(def prop-no-42
  (prop/for-all [v (gen/vector gen/int)]
    (not (some #{42} v))))

Run test.check...

(tc/quick-check 100 prop-no-42)
;; => {:result false,
       :failing-size 45,
       :num-tests 46,
       :fail [[10 1 28 40 11 -33 42 -42 39 -13 13 -44 -36 11 27 -42 4 21 -39]],
       :shrunk {:total-nodes-visited 38,
                :depth 18,
                :result false,
                :smallest [[42]]}}

Krakow Decompressed

Krakow Decompressed

(or 'What I learned @EuroClojure 2014')

Clojure Ireland

3rd Sept 2014, Dublin

Part 1.

Swagger & Prismatic Schema

To document & validate an API developed in Clojure

Prismatic Schema

Define a data-type with Schema

Test a sample of valid data

Pass invalid data to Schema

Compojure-api

Integrates several packages

Compojure & Ring (basic web-stack)

Prismatic Schema (to validate data-types)

ring-swagger (generate JSON to document an API)

Define data-type & set up routing...

Define an API endpoint...

Swagger UI

JavaScript to consume JSON to document an API.

Available for many languages (not just Clojure)

Alternatives to Compojure-api

Alternative to ring-swagger

Part 1 was inspired by...

"Schema & Swagger: making your Clojure web APIs more awesome", by Tommi Reiman.

Part 2.

JVM breakglass

A dynamic backdoor to diagnose a static (Java) system.

JVM- breakglass

breakglass demo

One-page tutorial-style guide to using JVM Breakglass

Part 2 was inspired by...

"JVM Break Glass - Using a Clojure REPL to troubleshoot live Java/JVM processes", by Mathieu Gauthron

Part 3.

"Generative testing" with test.check

Make assertions about your code

Let the test-library bombard your functions with generated test-data.

test.check reimplements QuickCheck (available for Erlang, Haskell)

Generators

generate random data, of a given type; starts off simply

Properties

for making general statements about data

Test the sort function

Run tests against the sort function

Example of a bad property

Run test.check...

Part 3 was inspired by...

"Generative testing with clojure.test.check", by Philip Potter

Videos from EuroClojure 2014

Call to Action

Document & Validate APIs with Schema & Swagger

Build an API with Compojure-api (or Octohipster)

Diagnose a static Java system with JVM-breakglass

Generate test data with test.check

Questions