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考察 [kǎo chá]

  • to inspect
  • to observe and study
  • on-the-spot investigation

See the Line Dict entry for an audio sample.

Need help?

Are you

There is also a #kaocha channel on Clojurians Slack (sign up here), where users can help each other.



Features include

  • Filtering tests based on test names or metadata
  • Watch mode: watch the file system for changes and re-run tests
  • Pretty, pluggable reporting
  • Randomize test order
  • Detect when interrupted with ctrl-C and print report
  • Fail fast mode: stop at first failure and print report
  • Profiling (show slowest tests)
  • Dynamic classpath handling
  • Tests as data (get test config, test plan, or test results as EDN)
  • Extensible test types (clojure.test, Midje, ...)
  • Extensible through plugins
  • Tool agnostic (Clojure CLI, Leiningen, ...)

Quick start

This is no replacement for reading the docs, but if you're particularly impatient to try it out, or if you already know Kaocha and need a quick reference how to set up a new project, then this guide is for you.

Clojure CLI (tools.deps)

Add Kaocha as a dependency, preferably under an alias.

;; deps.edn
{:deps { ,,, }
 {:test {:extra-deps {lambdaisland/kaocha {:mvn/version "1.88.1376"}}
         :main-opts ["-m" "kaocha.runner"]}}}

Add a binstub called bin/kaocha

mkdir -p bin
echo '#!/usr/bin/env sh' > bin/kaocha
echo 'clojure -M:test "$@"' >> bin/kaocha
chmod +x bin/kaocha

If you're on windows and installed clojure into powershell then you can put this into kaocha.ps1 for use with powershell.exe

clojure -M:test "$args"

Or put this in kaocha.bat for use with cmd.exe

powershell -command clojure -M:test "%*"

Or put this in kaocha for use with msys2

powershell -command clojure -M:test "$@"


Add a profile and alias

;; project.clj
(defproject my-proj "0.1.0"
  :dependencies [,,,]
  :profiles {:kaocha {:dependencies [[lambdaisland/kaocha "1.88.1376"]]}}
  :aliases {"kaocha" ["with-profile" "+kaocha" "run" "-m" "kaocha.runner"]})

Add a binstub called bin/kaocha

mkdir -p bin
echo '#!/usr/bin/env sh' > bin/kaocha
echo 'lein kaocha "$@"' >> bin/kaocha
chmod +x bin/kaocha


In your build.boot add the Kaocha dependency, and import the Kaocha task

;; build.boot
(set-env! :source-paths #{"src"}
          :dependencies '[[lambdaisland/kaocha-boot "..."]])

(require '[kaocha.boot-task :refer [kaocha]])

Add a binstub called bin/kaocha

mkdir -p bin
echo '#!/usr/bin/env sh' > bin/kaocha
echo 'boot kaocha "$@"' >> bin/kaocha
chmod +x bin/kaocha

Clojure CLI (tools.deps) :exec-fn alternative

We also support using the Clojure CLI :exec-fn/-X. However, we recommend the binstub approach above because it allows you to use traditional long and short options. If you nonetheless prefer :exec-fn/-X, you can set up deps.edn:

;; deps.edn
{:deps { ,,, }
 {:test {:extra-deps {lambdaisland/kaocha {:mvn/version "1.88.1376"}}
         :exec-fn kaocha.runner/exec-fn
         :exec-args {}}}}

And then Kaocha can be invoked this way: clojure -X:test

Generally speaking, we recommend using tests.edn for all of your configuration rather than putting it in exec-args unless there's an alternative combination of options you frequently run.

In that case, you can put configuration options :exec-args as though it were tests.edn. Let's say you frequently use watch with :fail-fast and a subset of tests skipped. You could save that configuration with an additional alias: clojure -X:watch-test like so:

;; deps.edn
{:deps { ,,, }
 {:test {:extra-deps {lambdaisland/kaocha {:mvn/version "1.88.1376"}}
         :exec-fn kaocha.runner/exec-fn
         :exec-args {}}
 :watch-test {:extra-deps {lambdaisland/kaocha {:mvn/version "1.88.1376"}}
         :exec-fn kaocha.runner/exec-fn
         :exec-args {:watch? true
	 :skip-meta :slow
	 :fail-fast? true }}}}

If you wanted to turn off fail-fast temporarily, you could run clojure -X:watch-test :fail-fast? false

You can also pass exec-args on the command line like so:

clojure -X:test :print-config true :kaocha.plugin.randomize/seed 603964682


Kaocha is compatible with Babashka.

You can create a bb.edn file:

{:paths ["src" "test"]
 :deps {lambdaisland/kaocha {:mvn/version "1.88.1376"}}}

Then you can create a binstub named bin/kaocha-bb:

#!/usr/bin/env bash
bb -m kaocha.runner/-main  $@

If you exclusively want to run tests using Babashka, you can of course call it bin/kaocha.

All tools

By default, Kaocha assumes that:

  • source files are in the src/ folder,
  • test files are in the test/ folder,
  • all test namespaces names end with -test (e.g. my-project.core-test). Also, the default test suite id is :unit (just unit on the command line).

If your tests don't seem to run (outcome is 0 tests, 0 assertions, 0 failures) you may need to write up your own configuration: add a tests.edn at the root of the project to configure actual test and source paths, and optionally set a reporter or load plugins (cf. Configuration in the documentation).

Example of a catch-all tests.edn config file (should run all tests found in src/ and /test, in any namespace).

{:tests [{:id          :unit
          :test-paths  ["test" "src"]
          :ns-patterns [".*"]}]
          ;; :reporter
          ;; :plugins [:kaocha.plugin/profiling :kaocha.plugin/notifier]

Warning: this is not an optimal configuration. To avoid extra churn, you should try and target only folders and namespaces that actually contain tests.

Run your tests


# Watch for changes
bin/kaocha --watch

# Exit at first failure
bin/kaocha --fail-fast

# Only run the `unit` suite
bin/kaocha unit

# Only run a single test
bin/kaocha --focus

# Use an alternative config file
bin/kaocha --config-file tests_ci.edn

# See all available options
bin/kaocha --test-help

Third party projects

  • kaocha-noyoda Don't speak like Yoda, write (is (= actual expected)) instead of (is (= expected actual))
  • kaocha-test-ns-hook A Kaocha plugin for the test-ns-hook feature in cloure.test.


Kaocha requires Clojure 1.9 or later.

Lambda Island Open Source

Thank you! kaocha is made possible thanks to our generous backers. Become a backer on OpenCollective so that we can continue to make kaocha better.


kaocha is part of a growing collection of quality Clojure libraries created and maintained by the fine folks at Gaiwan.

Pay it forward by becoming a backer on our OpenCollective, so that we continue to enjoy a thriving Clojure ecosystem.

You can find an overview of all our different projects at lambdaisland/open-source.




We warmly welcome patches to kaocha. Please keep in mind the following:

  • adhere to the LambdaIsland Clojure Style Guide
  • write patches that solve a problem
  • start by stating the problem, then supply a minimal solution *
  • by contributing you agree to license your contributions as EPL 1.0
  • don't break the contract with downstream consumers **
  • don't break the tests

We would very much appreciate it if you also

  • update the CHANGELOG and README
  • add tests for new functionality

We recommend opening an issue first, before opening a pull request. That way we can make sure we agree what the problem is, and discuss how best to solve it. This is especially true if you add new dependencies, or significantly increase the API surface. In cases like these we need to decide if these changes are in line with the project's goals.

* This goes for features too, a feature needs to solve a problem. State the problem it solves first, only then move on to solving it.

** Projects that have a version that starts with 0. may still see breaking changes, although we also consider the level of community adoption. The more widespread a project is, the less likely we're willing to introduce breakage. See LambdaIsland-flavored Versioning for more info.


Copyright © 2018-2023 Arne Brasseur and contributors

Available under the terms of the Eclipse Public License 1.0, see LICENSE.txt

Can you improve this documentation? These fine people already did:
Arne Brasseur, Alys Brooks, A Brooks, François De Serres, Wes Morgan, The Alchemist, Rick Moynihan, rgkirch, Mitesh Shah, Matthew Boston, fdserr, Ben Lovell, Joel Kaasinen, zengxinhui, Artem Solomatin, Derek Passen, Daniel Compton, José Luis Lafuente, Jose V. Trigueros & Philos Kim
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