Bond

Bond is a spying and stubbing library, primarily intended for tests. This is a forked version from https://github.com/circleci/bond/ with support for per-thread stubbing and spying. The project version of this is "circle-ci-bond-base.forked-version". Based off of: circleci#47

[helpshift/bond "0.6.0.0.1.0"]

Usage

(ns test.foo
  (:require [bond.james :as bond :refer [with-spy with-local-spy]]
            [clojure.test :refer :all]))

(defn foo [x]
  (let [shaken (with-out-str (prn :martini))]
    [shaken]))

(defn bar [y]
  (foo y))

(deftest foo-is-called
  (with-spy [foo]
    (bar 2)
    (is (= 1 (-> foo bond/calls count)))))


;; local redefinition API:
(deftest foo-is-redefined-locally-only
  (let [futures [(future
                   (Thread/sleep 1000)
                   (with-local-spy [foo]
                     (= 1 (-> foo bond/local-calls count))))
                 (future
                   @(future
                      (Thread/sleep 1000)
                      (with-local-spy [foo]
                        (= 1 (-> foo bond/local-calls count)))))]]
    (with-spy [foo]
      (bar 2)
      (is (= 1 (-> foo bond/calls count))))
    (every? (fn [f] (true? @f)) futures)))

Bond provides two main macros, with-spy and with-local-spy. It takes a vector of defn vars (vars that resolve to fns). Each var will be redefined for the scope of the macro, wrapping the function to track arguments and call counts. At any point during the scope, you can call (bond/calls f), where f is a spied fn. calls returns a seq of maps, one for each call to fb. Each map contains the keys :args, a seq of args the fn was called with, and one of :return or :throw. The only difference between with-spy and with-local-spy is that with-local-spy redefines the fn only for the current thread. Other threads are not affected. This behaviour is same for all with-local* functions, and must be used in conjuction with local-calls instead of calls.

Bond also provides with-stub! and with-local-stub!. It works the same as with-spy, but redefines the function to return (constantly nil) (default), while also spying on it. This is generally preferable to Clojure's built-in with-redefs macro since it will throw an exception if the mocked function is called with the wrong number of arguments. You can specify an arbitrary function instead of the default (constantly nil) by providing a [fn-var replacement-fn] vector in place of just the fn name:

(ns test.foo
  (:require [bond.james :as bond :refer [with-stub!]]))

(defn foo [x] ...)

(defn bar [y] ...)

(deftest foo-is-called
  (with-stub! [[foo (fn [x] "foo")]
               [bar (fn [y] "bar")]]
    (is (= ["foo" "bar"] [(foo 1) (bar 2)]))))

(deftest consecutive-stubbing
  (with-stub! [[foo [(fn [x] "foo1")
                     (fn [x] "foo2")
                     (fn [x] "foo3")]]
               [bar (fn [y] "bar")]]
    (is (= ["foo1" "foo2" "foo3" "bar"] [(foo 1) (foo 1) (foo 1) (bar 2)]))))

(deftest foo-is-called-from-multiple-futures
  (let [futures [(future
                   (Thread/sleep 1000)
                   (bond/with-local-stub! [[foo (fn [x] "foo")]
                                           [bar (fn [y] "bar")]]
                     (= ["foo" "bar"] [(foo 1) (bar 2)])
                     (is (= 1 (-> foo bond/local-calls count)))))
                 (future
                   (Thread/sleep 1000)
                   (bond/with-local-stub! [[foo (fn [x] "foo 2")]
                                           [bar (fn [y] "bar 2")]]
                     (= ["foo 2" "bar 2"] [(foo 1) (bar 2)])
                     (is (= 1 (-> foo bond/local-calls count)))))]]
    (bond/with-stub! [[foo (fn [x] "foo 1")]
                      [bar (fn [y] "bar 2")]]
      (is (= ["foo 1" "bar 2"] [(foo 1) (bar 2)]))
      (is (= 1 (-> foo bond/calls count))))
    (is (every? true? (map deref futures)))))

Private functions can also be stubbed or spyed:

(ns test.foo)

(defn- foo [x] ...)

(ns test.bar
  (:require [bond.james :as bond :refer [with-stub!]]
            [test.foo :as foo]))

(deftest foo-is-called
  (with-local-stub! [[foo/foo (fn [x] "foo")]]
    (is (= "foo" (#'foo/foo 1)))
    (is (= [1] (-> #'foo/foo bond/local-calls first :args)))))

There is also a with-stub and with-local-stub macro which works like with-stub! and with-local-stub! but omits the argument check.

In addition to with-spy* and with-stub*, Bond also provides with-spy-ns/with-local-spy-ns and with-stub-ns which can spy/stub every function in a namespace in one go:

(ns test.foo
  (:require [bond.james :as bond]
            [clojure.test :refer (deftest is)]))

(defn foo [] :foo)

(defn bar [] :bar)

(deftest you-can-stub-entire-ns
  (is (= :foo (foo)))
  (is (= :bar (bar)))
  (bond/with-stub-ns [[foo (constantly :baz)]]
    (is (= :baz (foo)))
    (is (= :baz (bar)))))

There is an utility with-dynamic-redefs which can be used in place of with-redefs but the redefinition will only be seen by the current (Clojure) thread. This can be used aside from the rest of the bond library as well.

Notes

• The local* functions work with Clojure's binding conveyance, so if the body of the redefinition goes beyond Clojure threads, like say, a java.lang.Thread, then the binding conveyance will not work and the redefined definition will not be seen by the thread nor will the counts to those functions from that thread be correct.
• with-dynamic-redefs only support redefinition of functions for now. As a future todo, we plan to add support for vars along with functions.

Releasing

The following should be updated on the main branch before tagging:

• project.clj - version
• README.md - dependency coordinates
• CHANGELOG.md - summary of changes

License

Distributed under the Eclipse Public License.