Initialize plugin

Author: tushararora

README.md

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+# vue-cli-plugin-unit-karmajs
+
+Run unit tests in a @vue/cli project with Karma and Mocha
+
+## Install
+
+```bash
+$ vue add vue-cli-plugin-unit-karmajs
+```
+
+If you want to install it using npm:
+
+```bash
+$ npm install vue-cli-plugin-unit-karmajs
+$ vue invoke vue-cli-plugin-unit-karmajs
+```
+
+If you don't want to use `vue invoke`, install required devDependencies which are present in `generator/index.js`.
+
+## Usage
+
+`vue-cli-service test:unit [options] [...files]`
+
+### Injected commands:
+* `vue-cli-service test:unit`
+
+  Default files matches are: any files in tests/unit that end in `.spec.js`.
+
+  Command line options: 
+
+  * `--watch, -w`: run in watch mode
+
+NOTE: If you want to override default karma settings, you can use the `pluginOptions.karma` key in `vue.config.js` like this:
+
+```javascript
+pluginOptions: {
+  karma: {
+    files: [ 'tests/**/*.spec.js' ]
+  }
+}
+```
+
+This module is inspired from [vue-cli-plugin-unit-karma] which is not actively maintained now.
+
+
+[vue-cli-plugin-unit-karma]: https://github.com/davidwallacejackson/vue-cli-plugin-unit-karma

default-karma-config.js

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+    
+/**
+ * Default config for karma
+ */
+  
+module.exports = {
+  files: [
+    'tests/unit/**/*.spec.js'
+  ],
+
+  reporters: [ 'mocha' ],
+
+  browsers: [ 'Chrome', 'Firefox' ],
+
+  frameworks: [ 'mocha', 'chai' ],
+};

generator/index.js

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+module.exports = (api, _, __, invoking) => {
+  api.extendPackage( {
+    devDependencies: {
+      "@vue/test-utils": "^1.0.0-beta.29",
+      "chai": "^4.2.0",
+      "mocha": "^6.2.0"
+    },
+    scripts: {
+      "test:unit": "vue-cli-service test:unit"
+    }
+  } );
+};

index.js

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+module.exports = ( api, projectOptions ) => {
+  let karmaOptions = require( './default-karma-config' );
+
+  if ( projectOptions.pluginOptions && projectOptions.pluginOptions.karma ) {
+    karmaOptions = Object.assign( karmaOptions, projectOptions.pluginOptions.karma );
+  }
+
+  api.chainWebpack( webpackConfig => {
+    if ( process.env.NODE_ENV === 'test' ) {
+      webpackConfig.merge( {
+        target: 'node',
+        devtool: 'inline-cheap-module-source-map'
+      } );
+
+      // when target === 'node', vue-loader will attempt to generate
+      // SSR-optimized code. We need to turn that off here.
+      webpackConfig.module
+        .rule( 'vue' )
+        .use( 'vue-loader' )
+        .tap( options => {
+          options.optimizeSSR = false;
+          return options;
+        } );
+    }
+  } );
+
+  api.registerCommand( 'test:unit', {
+      description: 'Run unit tests with karma',
+      usage: 'vue-cli-service test:unit [options] [...files]',
+    }, ( args ) => {
+      const webpackConfig = api.resolveWebpackConfig();
+
+      process.env.VUE_CLI_BABEL_TARGET_NODE = true
+      process.env.VUE_CLI_BABEL_TRANSPILE_MODULES = true
+
+      return new Promise( ( resolve, reject ) => {
+        let KarmaServer = require( 'karma' ).Server;
+        let generateKarmaConfig = require( './karma.conf' );
+
+        let karmaServer = new KarmaServer(
+          generateKarmaConfig( {
+            webpackConfig,
+            karmaOptions,
+            watch: args.watch || args.w
+          } ), ( exitCode ) => {
+            console.log( `Karma exited with exitCode ${exitCode}` );
+
+            if ( exitCode === 0 ) {
+              resolve( exitCode );
+            } else {
+              reject( exitCode );
+            }
+          }
+        );
+
+        karmaServer.start();
+      } );
+    }
+  );
+};

karma.conf.js

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+const karmaConstants = require('karma').constants;
+const merge = require('webpack-merge');
+
+module.exports = ( { webpackConfig, karmaOptions, watch } ) => {
+  delete webpackConfig.entry;
+  webpackConfig = merge( webpackConfig, {
+    devtool: 'inline-source-map'
+  } );
+
+  const preprocessors = {};
+
+  karmaOptions.files.map( fileNameOrPattern => {
+    preprocessors[ fileNameOrPattern ] = [ 'webpack' ];
+  } );
+
+  let karmaConfig = {
+    files: karmaOptions.files,
+
+    reporters: karmaOptions.reporters,
+
+    logLevel: karmaConstants.LOG_ERROR,
+
+    autoWatch: watch,
+
+    singleRun: !watch,
+
+    browsers: karmaOptions.browsers,
+
+    frameworks: karmaOptions.frameworks,
+
+    preprocessors,
+
+    webpack: webpackConfig,
+
+    webpackMiddleware: {
+      stats: 'minimal'
+    }
+  };
+
+  return karmaConfig;
+};