State and Hooks

Chaining steps

Each step function receives, as first argument, what the previous step returned -- like a Ring handler chain. No world object, no dependency injection. A map is the usual choice, destructured by the next step:

(defwhen "my sentence to be matched with {string} and {string}"
         [{:keys [k1 k2]} param1 param2]
         (do-something param1 k2 param2) ...)

A step whose last form returns nil, true or false -- an assertion, a doseq, a println -- keeps the state it was given, instead of passing that value on. So a defthen that only asserts needs no trailing state:

(defthen "my cart should contain {number} item" [state n]
         (is (= n (count (:cart state)))))   ; the next step still gets state

Initial state

By default, the first step of a scenario receives an empty map {}. Give another one in the options of deffeature:

(deffeature my-specification "./path/to/feature/file"
            {:default-scenario-state {:foo "bar"}})

Hooks

The same options map takes the functions to run:

• :pre-run before the feature
• :post-run after the feature
• :pre-scenario-run before each scenario
• :post-scenario-run after each scenario

(defn before-all [] (prn "init feature components"))
(defn before-each [] (prn "init scenario components"))
(defn after-each [] (prn "clean scenario side effects"))
(defn clean [] (prn "reset and shut down components"))

(deffeature my-specification "./path/to/feature/file"
            {:pre-run           [#'before-all]
             :pre-scenario-run  [#'before-each]
             :post-scenario-run [#'after-each]
             :post-run          [#'clean]})

Hooks take no argument. The :post-* hooks run even when a step or a :pre-* hook throws.