WARN [middleware:karma]: Invalid file type, defaulting to js. ts

Question

When I run unit testing via karma, I got those warning:

12 02 2019 14:01:05.740:WARN [middleware:karma]: Invalid file type, defaulting to js. ts
12 02 2019 14:01:05.741:WARN [middleware:karma]: Invalid file type, defaulting to js. ts

I assumed that the type of the karma.conf.js file caused the issue, so I changed it to karma.conf.ts.

However the issue still happened, so it would be great if someone can tell me how to disable this warning.

Below is my karma.conf.ts file

module.exports = function karmaConfig(config) {
    config.set({

        singleRun: true,

        frameworks: [
            'jasmine'
        ],

        files: [
            'sdk/**/*.spec.ts'
        ],

        preprocessors: {
            'sdk/**/*.spec.ts': ['webpack', 'sourcemap'],
            'sdk/**/!(*.spec).ts': ['coverage']
        },

        browsers: [
            'PhantomJS'
        ],

        reporters: [
            'progress',
            'coverage',
            'junit'
        ],

        coverageReporter: {
            dir: 'coverage/',
            reporters: [
                { type: 'text-summary' },
                { type: 'html' },
                {
                    type: 'lcov',
                    dir: 'reports',
                    subdir: 'coverage'
                }
            ]
        },

        junitReporter: {
            outputFile: 'reports/junit/TEST-karma.xml',
            useBrowserName: false
        },

        transports: ['polling'],

        webpack: require('./webpack.config'),

        webpackMiddleware: {
            stats: 'errors-only'
        },

        logLevel: config.LOG_INFO,

    });
};

I use webpack 4.16.5 and karma 4.0.0

Answer 1

I ran into the same error message, and I believe a similar issue but in my case for .ttf font files causing:

19 11 2019 22:12:35.398:WARN [middleware:karma]: Invalid file type (ttf), defaulting to js.

From http://karma-runner.github.io/4.0/config/files.html:

The css and html types create link elements; the js, dart, and module elements create script elements. The dom type includes the file content in the page, used, for example, to test components combinging HTML and JS.

So I believe if you want to add a resource with a different file type as a link it should be type HTML in the files config. The following worked for me:

{
    pattern: 'resources/fonts/**/*.ttf',
    type: 'html',
    served: true,
    included: true
},

Not sure how .ts files should be included in an HTML page (as shouldn't they be transpiled to JS?) but you could try setting the type to js.