Karma run single test - karma-runner

Question

I use karma to run tests. I have many tests and running all tests is a very slow process. I want to run only a single test in order to spend less time, because all tests are run about 10 minutes.
Is it possible?

Answer 1

If you are using the Karma/Jasmine stack, use:
fdescribe("when ...", function () { // to [f]ocus on a single group of tests
fit("should ...", function () {...}); // to [f]ocus on a single test case
});
... and:
xdescribe("when ...", function () { // to e[x]clude a group of tests
xit("should ...", function () {...}); // to e[x]clude a test case
});
When you're on Karma/Mocha:
describe.only("when ...", function () { // to run [only] this group of tests
it.only("should ...", function () {...}); // to run [only] this test case
});
... and:
describe.skip("when ...", function () { // to [skip] running this group of tests
it.skip("should ...", function () {...}); // to [skip] running this test case
});

Answer 2

Update: karma has changed.
Now use fit() and fdescribe()
f stands for focused!

Answer 3

For Angular users, try the following ways:
1. Visual Studio Code Extension
The easiest way is to use the vscode-test-explorer extension along with its child angular-karma-test-explorer and jasmine-test-adapter, you'll get a list of current test to run one by one if you want:
UPDATE DEC/2021: The extension has been deprecated, please consider using Karma Test Explorer instead.
2. Karma runner improvement
Currently there's an open issue to improve their current behaviour, you can follow their progress at their github page.
3. Directly modify test.ts
In my case, I wasn't able to use the extension way because of this bug, and so, as stated in this answer; I ended up modifying the test.ts file. For example if you want to test a single file named my.file.name.spec.ts:
// By default context looks like this
const context = require.context('./', true, /\.spec\.ts$/);
// Modify it, so it's RegExp matches the files that you're willing to test.
const context = require.context('./', true, /my\.file\.name\.spec\.ts$/);
For more details about require parameters you may find it here at their wiki.

Answer 4

a) You can pass a pattern that describes your single file as command line argument to the karma start command:
# build and run all tests
$ karma start
# build and run only those tests that are in this dir
$ karma start --grep app/modules/sidebar/tests
# build and run only this test file
$ karma start --grep app/modules/sidebar/tests/animation_test.js
Source: https://gist.github.com/KidkArolis/fd5c0da60a5b748d54b2
b) You can use a Gulp (or Grunt ect.) task that starts Karma for you. This gives you more flexibility on how to execute Karma. You are for example able to pass custom command line arguments to those tasks. This strategy is also useful if you want to implement a watch mode that only executes the changed tests. (The Karma watch mode would execute all tests.) Another use case would be to only execute tests for files with local changes before you do a commit.
Also see Gulp examples below.
c) If you use VisualStudio, you might want to add an external tool command to the context menu of the solution explorer. This way, you can start the test from that context menu instead of using the console. Also see
How to execute custom file specific command / task in Visual Studio?
Example Gulp file
//This gulp file is used to execute the Karma test runner
//Several tasks are available, providing different work flows
//for using Karma.
var gulp = require('gulp');
var karma = require('karma');
var KarmaServerConstructor = karma.Server;
var karmaStopper = karma.stopper;
var watch = require('gulp-watch');
var commandLineArguments = require('yargs').argv;
var svn = require('gulp-svn');
var exec = require('child_process').exec;
var fs = require('fs');
//Executes all tests, based on the specifications in karma.conf.js
//Example usage: gulp all
gulp.task('all', function (done) {
var karmaOptions = { configFile: __dirname + '/karma.conf.js' };
var karmaServer = new KarmaServerConstructor(karmaOptions, done);
karmaServer.on('browsers_change', stopServerIfAllBrowsersAreClosed); //for a full list of events see http://karma-runner.github.io/1.0/dev/public-api.html
karmaServer.start();
});
//Executes only one test which has to be passed as command line argument --filePath
//The option --browser also has to be passed as command line argument.
//Example usage: gulp single --browser="Chrome_With_Saved_DevTools_Settings" --filePath="C:\myTest.spec.js"
gulp.task('single', function (done) {
var filePath = commandLineArguments.filePath.replace(/\\/g, "/");
var karmaOptions = {
configFile: __dirname + '/karma.conf.js',
action: 'start',
browsers: [commandLineArguments.browser],
files: [
'./Leen.Managementsystem/bower_components/jquery/dist/jquery.js',
'./Leen.Managementsystem/bower_components/globalize/lib/globalize.js',
{ pattern: './Leen.Managementsystem/bower_components/**/*.js', included: false },
{ pattern: './Leen.Managementsystem.Tests/App/test/mockFactory.js', included: false },
{ pattern: './Leen.Managementsystem/App/**/*.js', included: false },
{ pattern: './Leen.Managementsystem.Tests/App/test/*.js', included: false },
{ pattern: filePath, included: false },
'./Leen.Managementsystem.Tests/App/test-main.js',
'./switchKarmaToDebugTab.js' //also see https://stackoverflow.com/questions/33023535/open-karma-debug-html-page-on-startup
]
};
var karmaServer = new KarmaServerConstructor(karmaOptions, done);
karmaServer.on('browsers_change', stopServerIfAllBrowsersAreClosed);
karmaServer.start();
});
//Starts a watch mode for all *.spec.js files. Executes a test whenever it is saved with changes.
//The original Karma watch mode would execute all tests. This watch mode only executes the changed test.
//Example usage: gulp watch
gulp.task('watch', function () {
return gulp //
.watch('Leen.Managementsystem.Tests/App/**/*.spec.js', handleFileChanged)
.on('error', handleGulpError);
function handleFileChange(vinyl) {
var pathForChangedFile = "./" + vinyl.replace(/\\/g, "/");
var karmaOptions = {
configFile: __dirname + '/karma.conf.js',
action: 'start',
browsers: ['PhantomJS'],
singleRun: true,
files: [
'./Leen.Managementsystem/bower_components/jquery/dist/jquery.js',
'./Leen.Managementsystem/bower_components/globalize/lib/globalize.js',
{ pattern: './Leen.Managementsystem/bower_components/**/*.js', included: false },
{ pattern: './Leen.Managementsystem.Tests/App/test/mockFactory.js', included: false },
{ pattern: './Leen.Managementsystem/App/**/*.js', included: false },
{ pattern: './Leen.Managementsystem.Tests/App/test/*.js', included: false },
{ pattern: pathForChangedFile, included: false },
'./Leen.Managementsystem.Tests/App/test-main.js'
]
};
var karmaServer = new KarmaServerConstructor(karmaOptions);
karmaServer.start();
}
});
//Executes only tests for files that have local changes
//The option --browser has to be passed as command line arguments.
//Example usage: gulp localChanges --browser="Chrome_With_Saved_DevTools_Settings"
gulp.task('localChanges', function (done) {
exec('svn status -u --quiet --xml', handleSvnStatusOutput);
function handleSvnStatusOutput(error, stdout, stderr) {
if (error) {
throw error;
}
var changedJsFiles = getJavaScriptFiles(stdout);
var specFiles = getSpecFiles(changedJsFiles);
if(specFiles.length>0){
console.log('--- Following tests need to be executed for changed files: ---');
specFiles.forEach(function (file) {
console.log(file);
});
console.log('--------------------------------------------------------------');
} else{
console.log('Finsihed: No modified files need to be tested.');
return;
}
var files = [
'./Leen.Managementsystem/bower_components/jquery/dist/jquery.js',
'./Leen.Managementsystem/bower_components/globalize/lib/globalize.js',
{ pattern: './Leen.Managementsystem/bower_components/**/*.js', included: false },
{ pattern: './Leen.Managementsystem.Tests/App/test/mockFactory.js', included: false },
{ pattern: './Leen.Managementsystem/App/**/*.js', included: false },
{ pattern: './Leen.Managementsystem.Tests/App/test/*.js', included: false }];
specFiles.forEach(function (file) {
var pathForChangedFile = "./" + file.replace(/\\/g, "/");
files = files.concat([{ pattern: pathForChangedFile, included: false }]);
});
files = files.concat([ //
'./Leen.Managementsystem.Tests/App/test-main.js', //
'./switchKarmaToDebugTab.js'
]);
var karmaOptions = {
configFile: __dirname + '/karma.conf.js',
action: 'start',
singleRun: false,
browsers: [commandLineArguments.browser],
files: files
};
var karmaServer = new KarmaServerConstructor(karmaOptions, done);
karmaServer.on('browsers_change', stopServerIfAllBrowsersAreClosed);
karmaServer.start();
}
});
function getJavaScriptFiles(stdout) {
var jsFiles = [];
var lines = stdout.toString().split('\n');
lines.forEach(function (line) {
if (line.includes('js">')) {
var filePath = line.substring(9, line.length - 3);
jsFiles.push(filePath);
}
});
return jsFiles;
}
function getSpecFiles(jsFiles) {
var specFiles = [];
jsFiles.forEach(function (file) {
if (file.endsWith('.spec.js')) {
specFiles.push(file);
} else {
if (file.startsWith('Leen\.Managementsystem')) {
var specFile = file.replace('Leen\.Managementsystem\\', 'Leen.Managementsystem.Tests\\').replace('\.js', '.spec.js');
if (fs.existsSync(specFile)) {
specFiles.push(specFile);
} else {
console.error('Missing test: ' + specFile);
}
}
}
});
return specFiles;
}
function stopServerIfAllBrowsersAreClosed(browsers) {
if (browsers.length === 0) {
karmaStopper.stop();
}
}
function handleGulpError(error) {
throw error;
}
Example settings for ExternalToolCommand in VisualStudio:
Title: Run Karma using Chrome
Command: cmd.exe
Arguments: /c gulp single
--browser="Chrome_With_Saved_DevTools_Settings" --filePath=$(ItemPath)
Initial directory: $(SolutionDir)
Use Output window: true

Answer 5

If you want to run karma test with angular, You just need to modify your test.ts file.
Find line const context = require.context('./', true, /\.spec\.ts$/);
If you want to run your.component.spec.ts modify line to: const context = require.context('./', true, /your\.component\.spec\.ts$/);

Answer 6

Changing it() to iit() should work for running single test.
Also, similar, for describe() block we can use ddescribe()

Answer 7

Change your karma conf to only include the test you want to run instead of a full directory.
Inside the files : [...]
You might want to comment the preprocessors if you need/want to debug your test in chrome to avoid having your js minified.

Answer 8

Yes, this is an old thread.
The following situation has occurred on me 2 - 3 times now in the past few years. More so when I haven't done much unit testing and have come back to it.
I started up my Karma and found the tests, after initial start up, should have completed within 1 second to now take 20 seconds. Additionally, attempting to debug the unit tests within Chrome became tediously slow. The network tab showed all the files taking 2 - 3 seconds per file.
Solution: I didn't realize Fiddler was open. Close it and restart your tests.

Answer 9

Answer proposal for special Angular/IE case: The only thing that worked so far for me using "karma-ie-launcher", in order to run IE as browser, was modifying "include" property of tsconfig.spec.json to explicitly reference target test file using universal qualified path and not globs e.g. "C:\filepath\my-test.spec.ts", for compilation purposes. "In addition" the test.ts file should be appropriately amended to target said file for test file limitation purposes. Be aware that the cache will need to be initially deleted in IE for this scheme to take effect.
(For Angular/Chrome case modification of test.ts alone would be sufficient.)