Awesome
clojure.test
for Expectations
A clojure.test
-compatible version of the classic Expectations testing library.
Where?
Try it out:
clj -Sdeps '{:deps {expectations/clojure-test {:mvn/version "RELEASE"}}}'
What?
This library brings expect
, more
, more-of
, etc from Expectations into the
clojure.test
world to be used instead of (or in addition to) the familiar is
macro. This library has no dependencies, other than clojure.test
itself, and
should be compatible with all existing clojure.test
-based tooling in editors
and command-line tools.
Works with Clojure 1.8 and later. Spec expectations are only available on Clojure 1.9 and later.
You can either use deftest
from clojure.test
, or defexpect
from
this library to wrap your tests.
Example REPL Session
What follows is an example REPL session showing some of what this library provides. For more detailed documentation, start with Getting Started and work your way through the sections listed there.
(ns my.cool.project-test
(:require [clojure.spec.alpha :as s]
[clojure.test :refer [deftest is]]
[expectations.clojure.test
:refer [defexpect expect expecting
approximately between between' functionally
side-effects]]))
;; mix'n'match libraries:
(deftest mixed
(is (= 2 (+ 1 1)))
(expect even? (+ 1 1)))
;; simple equality tests:
(defexpect equality
(expect 1 (* 1 1))
(expect "foo" (str "f" "oo")))
;; the expected outcome can be a regular expression:
(defexpect regex-1
(expect #"foo" "It's foobar!"))
;; since that has only a single expectation, it can be written more succinctly:
(defexpect regex-2 #"foo" "It's foobar!")
;; the expected outcome can be an exception type:
(defexpect divide-by-zero ArithmeticException (/ 12 0))
;; the expected outcome can be a predicate:
(defexpect no-elements empty? (list))
;; the expected outcome can be a type:
(defexpect named String (name :foo))
;; the expected outcome can be a Spec (require Clojure 1.9 or later):
(s/def ::value (s/and pos-int? #(< % 100)))
(defexpect small-value
(expect ::value (* 13 4)))
;; if the actual value is a collection, the expected outcome can be an element or subset "in" that collection:
(defexpect collections
(expect {:foo 1} (in {:foo 1 :cat 4}))
(expect :foo (in #{:foo :bar}))
(expect :foo (in [:bar :foo])))
;; just like clojure.test's testing macro to label groups of tests
;; you can use expecting to label groups of expectations (this uses
;; some of more advanced features listed below):
(defexpect grouped-behavior
(expecting "numeric behavior"
(expect (more-of {:keys [a b]}
even? a
odd? b)
{:a (* 2 13) :b (* 3 13)})
(expect pos? (* -3 -5)))
(expecting "string behavior"
(expect (more #"foo" "foobar" #(clojure.string/starts-with? % "f"))
(str "f" "oobar"))
(expect #"foo"
(from-each [s ["l" "d" "bar"]]
(str "foo" s)))))
Just like deftest
, the defexpect
macro creates a function that contains the test(s). You can run each function individually:
user=> (equality)
nil
If the test passes, nothing is printed, and nil
is returned. Let's look at a failing test:
user=> (defexpect inequality (* 2 21) (+ 13 13 13))
#'user/inequality
user=> (inequality)
FAIL in (inequality) (.../README.md:117)
expected: (=? (* 2 21) (+ 13 13 13))
actual: (not (=? 42 39))
nil
The output is produced by clojure.test
's standard reporting functionality.
The =?
operator is an extension to clojure.test
's assert-expr
multimethod
that allows for Expectations style of predicate-or-equality testing (based on
whether the "expected" expression resolves to a function or some other value):
user=> (defexpect not-at-all-odd odd? (+ 1 1))
#'user/not-at-all-odd
user=> (not-at-all-odd)
FAIL in (not-at-all-odd) (.../README.md:133)
expected: (=? odd? (+ 1 1))
actual: (not (odd? 2))
nil
Here we see the predicate (odd?
) being applied in the "actual" result from
clojure.test
.
Just like the is
macro, expect
can take an optional failure message as the third argument:
user=> (defexpect failure-msg
(expect even? (+ 1 1 1) "It's uneven!"))
#'user/failure-msg
user=> (failure-msg)
FAIL in (failure-msg) (.../README.md:149)
It's uneven!
expected: (=? even? (+ 1 1 1))
actual: (not (even? 3))
nil
Compatibility with Expectations
expectations.clojure.test
supports the following features from Expectations so far:
- simple equality test
- simple predicate test
- spec test (using a keyword that identifies a spec)
- class test -- see
named
above - exception test -- see
divide-by-zero
above - regex test -- see
regex-1
andregex-2
above (expect expected-expr (from-each [a values] (actual-expr a)))
(expect expected-expr (in actual-expr))
-- seecollections
above(expect (more-of destructuring e1 a1 e2 a2 ...) actual-expr)
(expect (more-> e1 a1 e2 a2 ...) actual-expr)
-- whereactual-expr
is threaded into eacha1
,a2
, ... expression(expect (more e1 e2 ...) actual-expr)
(expect expected-expr (side-effects [fn1 fn2 ...] actual-expr))
Read the Expectations documentation for more details of these features.
Why?
Given the streamlined simplicity of Expectations, you might wonder why you
would want to migrate your Expectations test suite to clojure.test
-style
named tests? The short answer is tooling! Whilst Expectations has
well-maintained, stable plugins for Leiningen and Boot, as well as an Emacs mode,
the reality is that Clojure tooling is constantly evolving and most of those
tools -- such as the excellent CIDER,
Cursive,
Chlorine (for Atom),
and Cognitect's test-runner
--
are going to focus on Clojure's built-in testing library first.
Support for the original form of Expectations, using unnamed tests, is
non-existent in Cursive, and can be problematic in other editors and tooling.
A whole ecosystem
of tooling has grown up around clojure.test
and to take advantage of
that with Expectations, we either need to develop compatible extensions to each
and every tool or we need Expectations to be compatible with clojure.test
.
One of the big obstacles for that compatibility is that, by default, Expectations
generates "random" function names for test code (the function names are based on the
hashcode of the text form of the expect
body), which means the test
name changes whenever the text of the test changes. To address that, the new
expectations.clojure.test
namespace introduces named expectations via
the defexpect
macro (mimicking clojure.test
's deftest
macro). Whilst this goes against the Test Names
philosophy that Expectations was created with, it buys us a lot in terms of
tooling support!
Differences from Expectations
Aside from the obvious difference of providing names for tests -- essential for
compatibility with clojure.test
-based tooling -- here are the other differences
to be aware of:
- You use standard
clojure.test
-based tooling --lein test
,boot test
, and Cognitect'stest-runner
-- instead of the Expectations-specific tooling. - Because of that, tests run when you decide, not at JVM shutdown (which is the default with Expectations).
- If you have Paul Stadig's Humane Test Output on your classpath, it will be activated and failures reported by
=?
will be compatible with it, providing better reporting. - Instead of the
in-context
,before-run
,after-run
machinery of Expectations, you can just useclojure.test
's fixtures machinery (use-fixtures
). As of 2.0.0,use-fixtures
is exposed directly viaexpectations.clojure.test
so you don't need to requireclojure.test
. - Instead of Expectations' concept of "focused" test, you can use metadata on tests and tell your test runner to "select" tests as needed (e.g., Leiningen's "test selectors", Boot's "filters", and
test-runner
's-i
/-e
options). freeze-time
,redef-state
, andwarn-on-iref-updates
are not (yet) implemented.- The undocumented
CustomPred
protocol is not implemented -- you can use plainis
and extendclojure.test
'sassert-expr
multimethod if you need that level of control.
Test & Development
To test, run clj -A:test:runner
(tests against Clojure 1.8).
Multi-version testing:
for v in 1.8 1.9 1.10
do
clojure -A:test:runner:$v
done
You can also run the tests with Humane Test Output enabled but you need to exclude the negative tests because they assume things about the test report data that HTO modifies:
for v in 1.8 1.9 1.10
do
clojure -A:test:runner:$v:humane -e :negative
done
License & Copyright
Copyright © 2018-2020 Sean Corfield, all rights reserved.
Distributed under the Eclipse Public License version 1.0.