Quick reference: monads and test.check generators

Combine monads with test.check generators to build them up out of smaller generators with dependencies: (require ‘[clojure.test.check.generators :as gen])(require ‘[clojure.algo.monads :as m])(m/defmonad gen-m   [m-bind gen/bind    m-result gen/return]) (def vector-and-elem  (m/domonad gen-m    [n (gen/choose 1 10)     v (gen/vector gen/int n)     e (gen/element v)]    [v, e])) (gen/sample vector-and-elem);; ([[0 0] 0]     [[0 -1 1 0 -1 0 -1 1] 0]   …

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Testing akka actor termination

When testing akka code, I want to make sure a particular actor gets shut down within a time limit. I used to do it like this:  Thread.sleep(2.seconds) assertTrue(actorRef.isTerminated()) That isTerminated method is deprecated since Akka 2.2, and good thing too, since my test was wasting everyone’s time. Today I’m doing this instead: import akka.testkit.TestProbeval probe = …

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Property-based testing of higher-order functions

Property-based testing and functional programming are friends, because they’re both motivated by Reasoning About Code. Functional programming is about keeping your functions data-in, data-out so that you can reason about them. Property-based testing is about expressing the conclusions of that reasoning as properties, then showing that they’re (probably) true by testing them with hundreds of …

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