An alternative to clojure.test, aiming to be feature-rich and easily extensible.
Add it to your deps.edn or project.clj:
{:aliases
{:test {:extra-deps {io.github.noahtheduke/lazytest {:mvn/version "0.4.2"}}
:extra-paths ["test"]
:main-opts ["-m" "lazytest.main"]}}}In a test file:
(ns example.readme-test
(:require [lazytest.core :refer [defdescribe describe expect it]]))
(defdescribe seq-fns-test
(describe keep
(it "should reject nils"
(expect (= '(1 2 3) (keep identity [nil 1 2 3]))))
(it "should return a sequence"
(expect (seq? (seq (keep identity [nil])))))))From the command line:
$ clojure -M:test
lazytest.readme-test
seq-fns-test
#'clojure.core/keep
√ should reject nils
× should return a sequence FAIL
lazytest.readme-test
seq-fns-test
#'clojure.core/keep
should return a sequence:
Expectation failed
Expected: (seq? (seq (keep identity [nil])))
Actual: nil
Evaluated arguments:
* ()
in lazytest/readme_test.clj:11
Ran 2 test cases in 0.00272 seconds.
1 failure.clojure.test has existed since 1.1 and while it's both ubiquitous and useful, it has a number of problems:
istightly couples running test code and reporting on it.areis strictly worse thandoseqormapv.clojure.test/reportis^:dynamic, but that leads to being unable to combine multiple reporters at once, or libraries such as Leiningen monkey-patching it.- Tests can't be grouped or bundled in any meaningful way (no, defining
test-ns-hookdoes not count). testingcalls aren't real contexts, they're just strings.- Fixtures serve a real purpose but because they're set on the namespace, their definition is side-effecting and using them is complicated and hard to reuse.
There exists very good libraries like Expectations v2, kaocha, eftest, Nubank's matcher-combinators, Cognitect's test-runner that improve on clojure.test, but they're all still built on a fairly shaky foundation. I think it's worthwhile to explore other ways of being, other ways of doing stuff. Is a library like lazytest good? is a testing framework like this good when used in clojure? I don't know, but I'm willing to try and find out.
Other alternatives such as Midje, classic Expectations, and speclj attempted to correct some of those issues and they made good progress. However, some (such as Midje) relied on non-list style (test => expected) and most don't worked well with modern repl-driven development practices (as seen by the popularity of the aforementioned clojure.test-compatible Expectations v2).
I like the ideas put forth in Alessandra's post above about Lazytest and hope to experiment with achieving them 14 years later, while borrowing heavily from the work in both the Clojure community and test runners frameworks in other languages.
With the above :test alias, you run with clojure -M:test [options] where [options] are any of the below.
-d,--dir DIR: Directory containing tests. (Defaults totest.)-n,--namespace NS-SYM: Run only the specified test namespaces. Can be given multiple times.-v,--var VAR-SYM: Run only the specified fully-qualified symbol.-i,--include KEYWORD: Run only test sequences or vars with this metadata keyword.-e,--exclude KEYWORD: Exclude test sequences or vars with this metadata keyword.--output OUTPUT: Output format. Can be given multiple times. (Defaults tonested.)--help: Print help information.--version: Print version information.
Note: If both --namespace and --var are provided, then Lazytest will run all tests within the namespaces AND the specified vars. They are inclusive, not exclusive.
Note: --exclude overrides --include, if both are provided.
The primary api is found in lazytest.core namespace. It mimics the behavior-driven testing style popularized by libraries such as RSpec and Mocha.
Define tests with defdescribe, group test suites and test cases together into a suite with describe, and define test cases with it. describe can be nested. defdescribe's docstring is optional, describe and it's docstrings are not.
(defdescribe +-test "with integers"
(it "computes the sum of 1 and 2"
(expect (= 3 (+ 1 2))))
(it "computes the sum of 3 and 4"
(assert (= 7 (+ 3 4)))))The expect macro is like assert but carries more information about the failure, such as the given form, the returned value, and the location of the call. It throws an exception if the expression does not evaluate to logical true.
If an it runs to completion without throwing an exception, the test case is considered to have passed.
In addition to finding the tests defined with defdescribe, Lazytest also checks all vars for :test metadata. If the :test metadata is a function, a test case, or a test suite, it's treated as a top-level defdescribe for the associated var and executed just like other tests. :test functions are given the doc string "`:test` metadata".
How to write them:
(ns example.metadata-test ...)
(defn fn-example {:test #(expect ...)})
(defn test-case-example {:test (it "test case example docstring" ...)})
(defn suite-example {:test (suite ...)})
(defn describe-example {:test (describe "top level docstring" ...)})How they're printed:
example.metadata-test
#'example.metadata-test/fn-example
√ `:test` metadata
#'example.metadata-test/test-case-example
√ test case example docstring
#'example.metadata-test/suite-example
√ first test case
√ second test case
#'example.metadata-test/describe-example
top level docstring
√ third test case
√ fourth test case
These can get unweildy if multiple test cases are included before a given implementation, so I recommend either moving them to a dedicated test file or moving the attr-map to the end of the function definition:
(defn describe-example
([a b]
(+ a b))
{:test (describe "Should be simple addition"
(it "handles ints"
(expect (= 2 (describe-example 1 1))))
(it "handles floats"
(expect (= 2.0 (describe-example 1.0 1.0)))))})All of the test suite and test case macros (defdescribe, describe, it, expect-it) take a metadata map after the docstring. Adding :focus true to this map will cause only that test/suite to be run. Removing it will return to the normal behavior (run all tests).
(defdescribe my-test
"fancy test"
{:focus true}
...)Additionally, you can use the cli option -n/--namespace to specify one or more namespaces to focus wholly, or you can use the cli option -v/--var to specify one or more fully-qualified vars to focus. This allows for testing from the command line without modifying source files.
To partition your test suite based on metadata, you can use -i/--include to only run tests with the given metadata, or -e/--exclude to skip tests with the given metadata.
Lazytest comes with a number of reporters built-in. These print various information about the test run, both as it happens and surrounding execution. They are specified at the cli with --output and can be simple symbols or fully-qualified symbols. If a custom reporter is provided, it must be fully-qualified. (Otherwise, Lazytest will try to resolve it to the lazytest.reporters namespace and throw an exception.)
The default Lazytest reporter. Inspired heavily by Mocha's Spec reporter, it prints each suite and test case indented as they are written in the test files.
lazytest.core-test
it-test
√ will early exit
√ arbitrary code
with-redefs-test
redefs inside 'it' blocks
× should be rebound FAIL
redefs outside 'it' blocks
√ should not be rebound
lazytest.core-test
with-redefs-test
redefs inside 'it' blocks
should be rebound:
this should be true
Expected: (= 7 (plus 2 3))
Actual: false
Evaluated arguments:
* 7
* 6
Only in first argument:
7
Only in second argument:
6
in lazytest/core_test.clj:29
Ran 90 test cases in 0.06548 seconds.
1 failure.
A minimalist reporter. Prints passing test cases as green . and failures as red F during the test run. Test suites are grouped with parentheses ((/)). It also prints the failure results and summary as in lazytest.reporters/nested, which has been elided below for brevity.
(...)(..F................)(.....)(..)(..)(....)(........)(........................................)(.......)
Mimics clojure.test's default reporter, treating suite and test-case docstrings as testing strings.
Testing lazytest.core-test
FAIL in (with-redefs-test) (lazytest/core_test.clj:29)
with-redefs-test redefs inside 'it' blocks should be rebound
this should be true
expected: (= 7 (plus 2 3))
actual: false
Ran 25 tests containing 90 test cases.
1 failure, 0 errors.
Prints nothing. Useful if all you want is the return code.
Prints loudly about every step of the run. Incredibly noise, not recommended for anything other than debugging Lazytest internals.
The entry-points are at lazytest.repl: run-all-tests, run-tests, and run-test-var. The first runs all loaded test namespaces, the second runs the provided namespaces (either a single namespace or a collection of namespaces), and the third runs a single test var. If your editor can define custom repl functions, then it's fairly easy to set these as your test runner.
Neovim with Conjure:
-- in your init.lua
local runners = require("conjure.client.clojure.nrepl.action")
runners["test-runners"].lazytest = {
["namespace"] = "lazytest.repl",
["all-fn"] = "run-all-tests",
["ns-fn"] = "run-tests",
["single-fn"] = "run-test-var",
["default-call-suffix"] = "",
["name-prefix"] = "#'",
["name-suffix"] = ""
}
vim.g["conjure#client#clojure#nrepl#test#runner"] = "lazytest"VSCode with Calva:
"calva.customREPLCommandSnippets": [
{
"name": "Lazytest: Test All Tests",
"snippet": "(lazytest.repl/run-all-tests)"
},
{
"name": "Lazytest: Test Current Namespace",
"snippet": "(lazytest.repl/run-tests $editor-ns)"
},
{
"name": "Lazytest: Test Current Var",
"snippet": "(lazytest.repl/run-test-var #'$top-level-defined-symbol)"
}
],IntelliJ with Cursive:
Name: Lazytest - Test All Tests
Execute Command: (lazytest.repl/run-all-tests)
Execution Namespace: Execute in current file namespace
Results: Print results to REPL output
Name: Lazytest - Test Current Namespace
Execute Command: (lazytest.repl/run-tests ~file-namespace)
Execution Namespace: Execute in current file namespace
Results: Print results to REPL output
Name: Lazytest - Test Current Var
Execute Command: (lazytest.repl/run-test-var #'~current-var)
Execution Namespace: Execute in current file namespace
Results: Print results to REPL output
The smallest unit of testing is a test case, which is a function (see lazytest.test-case/test-case). When the function is called, it may throw an exception to indicate failure. If it does not throw an exception, it is assumed to have passed. The return value of a test case is always ignored. Running a test case may have side effects.
NOTE: The macros lazytest.describe/it and lazytest.describe/expect-it create test cases.
Tests cases are organized into suites. A test suite is a function (see lazytest.suite/suite) that returns a test sequence. A test sequence (see lazytest.suite/test-seq) is a sequence, possibly lazy, of test cases and/or test suites. Suites, therefore, may be nested inside other suites, but nothing may be nested inside a test case.
NOTE: The macros lazytest.describe/defdescribe and lazytest.describe/describe create test suites.
A test suite function SHOULD NOT have side effects; it is only used to generate test cases and/or other test suites.
A test runnner is responsible for expanding suites (see lazytest.suite/expand-suite) and running test cases (see lazytest.test-case/try-test-case). It may also provide feedback on the success of tests as they run.
The test runner also returns a sequence of results, which are either suite results (see lazytest.suite/suite-result) or test case results (see lazytest.test-case/test-case-result). That sequence of results is passed to a reporter, which formats results for display to the user. Multiple reporters are provided, see the namespace lazytest.reporters.
Originally by Alessandra Sierra.
Currently developed by Noah Bogart.
Licensed under Eclipse Public License 1.0