ClojureScript preprocessor for Cypress using shadow-cljs
npm install cypress-clojurescript-preprocessorA Cypress preprocessor for ClojureScript, which uses Shadow CLJS for processing Cypress tests written in ClojureScript.
The plugin works by inspecting the Cypress integrationFolder (by default, cypress/integration) for ClojureScript files (*.cljs, e.g. cypress/integration/my_app/app_test.cljs -> (ns my-app.app-test)) and generates a shadow-cljs.edn configuration file with a build for each test file. This configuration is then used to compile the tests into Javascript before submitting to the browser.
The shadow-cljs server is kept running while the Cypress runner is active. When a test is run, the test file is watched for changes and a recompile is done if the test file is changed and Cypress is notified to rerun the test. The first compile is a bit slow, but subsequent compiles are fast (the plugin uses shadow-cljs compile command, which defaults to optimizations: none).
1. Create a project
``sh`
$ mkdir cypress-cljs-sample
$ cd cypress-cljs-sample
$ echo {} > package.json
2. Install Cypress
`sh`
npm install cypress --save-dev
3. Install cypress-clojurescript-preprocessor
`sh`
npm install cypress-clojurescript-preprocessor
4. Configure ClojureScript preprocessor
`sh`
$ mkdir -p cypress/plugins
$ cat << EOF > cypress/plugins/index.js
const makeCljsPreprocessor = require('cypress-clojurescript-preprocessor');
/**
* @type {Cypress.PluginConfig}
*/
module.exports = (on, config) => {
on('file:preprocessor', makeCljsPreprocessor(config));
};
EOF
This will delegate files other than *.cljs to the default Browserify preprocessor. If you need to run other preprocessors, then combine them with for example:
`js`
module.exports = (on, config) => {
const browserifyPreprocessor = makeBrowserifyPreprocessor();
const cljsPreprocessor = makeCljsPreprocessor(config);
// Use the default Browserify preprocessor for files other than *.cljs
on('file:preprocessor', (file) => file.filePath.endsWith('.cljs') ? cljsPreprocessor(file) : browserifyPreprocessor(file));
};
5. Write test in ClojureScript
`sh
$ mkdir -p cypress/integration/examples
$ cat << EOF > cypress/integration/examples/window.cljs
(ns examples.window
(:require-macros [latte.core :refer [describe beforeEach it]]))
(def cy js/cy)
(describe "Window"
(beforeEach []
(.visit cy "https://example.cypress.io/commands/window"))
(it "cy.window() - get the global window object" []
(.should (.window cy) "have.property" "top")))
EOF
`
6. Run test
`sh`
./node_modules/.bin/cypress open
You can active REPL into a test in the browser that Cypress is controlling.
1. Lookup NREPL port used by the shadow-cljs server
`
$ cat .preprocessor-cljs/.shadow-cljs/nrepl.port
50796
2. Connect to the NREPL server and list builds
`
shadow.user> (shadow/get-build-ids)
(:npm :local :window_foo :window)
3. Open a test in the Cypress runner
4. Start shadow-cljs watch on the test that is open in the Cypress runner
`
shadow.user> (shadow/watch :window)
[:window] Configuring build.
[:window] Compiling ...
[:window] Build completed. (119 files, 0 compiled, 0 warnings, 1.22s)
:watching
The build-id is a keyword of the test file name
5. Start a ClojureScript repl
`
shadow.user> (shadow/repl :window)
To quit, type: :cljs/quit
[:selected :window]
cljs.user> (js/alert "plop") ;; To try out that it works
Now you can use the slightly undocumented now command to execute Cypress command immediately, for example, to select an option:
`
cljs.user> (-> (.now js/cy "get" "#some-opt")
(.then (fn [el]
(.now js/cy "select" el "two"))))
#object[Promise [object Promise]]
6. When done, exit the repl and stop shadow-cljs watch for the repl build
`
cljs.user> :cljs/quit
Exited CLJS session. You are now in CLJ again.
:cljs/quit
shadow.user>
(shadow/stop-worker :window)
Worker shutdown.
:stopped
Some references to the now command:
* https://github.com/cypress-io/cypress/issues/6080#issuecomment-570481923
* https://docs.cypress.io/guides/guides/debugging#Run-Cypress-command-outside-the-test
* https://github.com/cypress-io/cypress/issues/8195
* https://github.com/cypress-io/cypress/issues/3636#issuecomment-511315778
The Shadow CLJS configuration used by the preprocessor may be overridden via a shadow-cljs-override.edn file, which is merged on top of the default configuration with meta-merge. By default, [mocha-latte "0.1.2"] and [chai-latte "0.2.0"] are included in the shadow-cljs.edn configuration used by the preprocessor.
The working directory of the shadow-cljs compiler that is driven by the preprocessor is the cypress folder. Because of this, in order to include shared code that is in a folder at the same level as the cypress directory, use a relative (or absolute path) e.g.
`
$ tree -I "node_modules" -P common.cljs\|window.cljs
.
├── cypress
│ ├── fixtures
│ ├── integration
│ │ └── examples
│ │ └── window.cljs
│ ├── plugins
│ └── support
└── src ;; shared code directory
└── net
└── tiuhti
└── common.cljs
$ cat shadow-cljs-override.edn
{:source-paths ["../src"]} ;; path relative to directorysrc
$ head -3 cypress/integration/examples/window.cljs
(ns examples.window
(:require-macros [latte.core :refer [describe beforeEach it]])
(:require [net.tiuhti.common :as common])) ;; require namespace in the directory`
Dependencies used by the shared code would have to be specified in the :dependencies key in shadow-cljs-override.edn file.
Here's some notes on how to develop this library.
The preprocessor is written in ClojureScript and compiled to a npm library with the help of shadow-cljs. To develop the library in a ClojureScript repl:
1. Start node repl via shadow-cljs node-repl
2. Connect to the server for example from Emacs with cider: cider-connect
3. In at the shadow.user> prompt, switch to the node repl via: (shadow/repl :node-repl)
To use a local version of the preprocessor, point the client project to the local clone of the preprocessor:
`0% cat package.json`
{
"devDependencies": {
"cypress": "^7.6.0",
"shadow-cljs": "^2.14.5" ;; <-- Also, need to have shadow-cljs installed in the client project
},
"dependencies": {
"cypress-clojurescript-preprocessor": "../cypress-clojurescript-preprocessor" ;; <-- Directory of the local copy
}
}
Note the the client project also needs shadow-cljs to be installed (apparently :)).
Then, compile your changes via
`
$ npm run prepare
And (re)start Cypress in the client project:
`
$ ./node_modules/.bin/cypress open
* 0.2.0
* Support REPL in an open test, allows to use the "now" command
* Finally fix zombie processes after exit, by using signal-exit, thanks to this blog post
* Detech shadow-cljs startup by polling port/pid files and remove race condition around subprocess stdout/stderr
* 0.1.7
* Bump shadow-cljs to 2.14.5
* Call process/exit to not leave zombies when Cypress exits
* When adding a new test while the preprocessor is running
* Use same optimization level as for initial build config
* Prevent duplicate merge of shadow-cljs-override.edn`
* 0.1.6 Support namespaces with multiple segments (thanks @martinklepsch !), also files with underscore. Bump chokidar to 3.5.2
* 0.1.5 Merge override config ontop final config, allows to add additional :source-paths
* 0.1.4 Bundle browserify preprocessor
* 0.1.3 Add shadow-cljs-override.edn
* 0.1.2 Bundle Bundle mocha-latte and chai-latte
* 0.1.0 Initial release