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mentat/src/datomish/test_macros.cljc

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Add an async and async testing framework. This is a well-worn idea: use a `promise-channel` of `[result nil]` or `[nil error]` pairs. The `go-pair` and `<?` macros handle catching exceptions (important, given that synchronous CLJ code expects to throw rather than return an error promise or similar), allowing code like: ``` (go-pair (let [result (<? (pair-chan-fn))] (when (not result) (throw (Exception. "No result!"))) (transform result))) ``` to be expressed naturally. These are the equivalents of `async` and `await` in JS. The implementation is complicated by significant incompatibilities between CLJ and CLJS. The solution presented here takes care to separate the macro definitions into CLJ. Sadly, this requires namespacing the per-environment symbols explicitly; but we hope to minimize such code in files like this. The most significant restriction to this approach is that consumers must require the transitive dependencies of the macro-defining modules. See the included tests (both CLJ and CLJS) for the appropriate incantations (for pair-chan, core.async, and test).
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;; This Source Code Form is subject to the terms of the Mozilla Public
;; License, v. 2.0. If a copy of the MPL was not distributed with this
;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
(ns datomish.test-macros
Expose `with-open` to CLJS.
2016-07-12 04:57:20 +00:00
(:refer-clojure :exclude [with-open])
Add an async and async testing framework. This is a well-worn idea: use a `promise-channel` of `[result nil]` or `[nil error]` pairs. The `go-pair` and `<?` macros handle catching exceptions (important, given that synchronous CLJ code expects to throw rather than return an error promise or similar), allowing code like: ``` (go-pair (let [result (<? (pair-chan-fn))] (when (not result) (throw (Exception. "No result!"))) (transform result))) ``` to be expressed naturally. These are the equivalents of `async` and `await` in JS. The implementation is complicated by significant incompatibilities between CLJ and CLJS. The solution presented here takes care to separate the macro definitions into CLJ. Sadly, this requires namespacing the per-environment symbols explicitly; but we hope to minimize such code in files like this. The most significant restriction to this approach is that consumers must require the transitive dependencies of the macro-defining modules. See the included tests (both CLJ and CLJS) for the appropriate incantations (for pair-chan, core.async, and test).
2016-07-11 23:48:40 +00:00
(:require
[datomish.pair-chan]))
;; From https://github.com/plumatic/schema/blob/bf469889b730feb09448fd085be5828f28425b41/src/clj/schema/macros.clj#L10-L19.
(defn cljs-env?
"Take the &env from a macro, and tell whether we are expanding into cljs."
[env]
(boolean (:ns env)))
(defmacro if-cljs
"Return then if we are generating cljs code and else for Clojure code.
https://groups.google.com/d/msg/clojurescript/iBY5HaQda4A/w1lAQi9_AwsJ"
[then else]
(if (cljs-env? &env) then else))
;; It's a huge pain to declare cross-environment macros. This is awful, but making the namespace a
;; parameter appears to be *even worse*.
(defmacro deftest-async
[name & body]
`(if-cljs
(cljs.test/deftest
~(with-meta name {:async true})
(cljs.test/async done#
(->
(datomish.pair-chan/go-pair ~@body)
(cljs.core.async/take! (fn [v# e#]
(cljs.test/is (= e# nil))
(done#))))))
(clojure.test/deftest
~(with-meta name {:async true})
(let [[v# e#] (clojure.core.async/<!! (datomish.pair-chan/go-pair ~@body))]
(clojure.test/is (= e# nil))))))
Expose `with-open` to CLJS.
2016-07-12 04:57:20 +00:00
;; CLJS doesn't expose `with-open`, for reasons unknown. Duplicate the definition of
;; `with-open` (and `assert-args`) here.
;; See https://github.com/clojure/clojure/blob/clojure-1.7.0/src/clj/clojure/core.clj#L3679-L3698.
(defmacro ^{:private true} assert-args
[& pairs]
`(do (when-not ~(first pairs)
(throw (IllegalArgumentException.
(str (first ~'&form) " requires " ~(second pairs) " in " ~'*ns* ":" (:line (meta ~'&form))))))
~(let [more (nnext pairs)]
(when more
(list* `assert-args more)))))
(defmacro with-open
"bindings => [name init ...]
Evaluates body in a try expression with names bound to the values
of the inits, and a finally clause that calls (.close name) on each
name in reverse order."
{:added "1.0"}
[bindings & body]
(assert-args
(vector? bindings) "a vector for its binding"
(even? (count bindings)) "an even number of forms in binding vector")
(cond
(= (count bindings) 0) `(do ~@body)
(symbol? (bindings 0)) `(let ~(subvec bindings 0 2)
(try
(with-open ~(subvec bindings 2) ~@body)
(finally
(. ~(bindings 0) close))))
:else (throw (java.lang.IllegalArgumentException.
"with-open only allows Symbols in bindings"))))
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