Configure-unit-tests-on-local-machine.md

+# Configure unit tests on local machine
+
+https://jasmine.github.io/ \
+https://karma-runner.github.io/latest/index.html
+
+## Write unit tests
+
+For writing unit tests we will use the Jasmine framework. 
+
+1. Initialize NodeJS project with `npm init` and install jasmine:
+
+```
+npm init
+npm install --save-dev jasmine
+```
+
+2. Unit tests are located in `*.spec.js` files. Create spec file with unit tests for `sum.js`, in this tutorial we will test the `sum` function only:
+
+js/sum.spec.js
+```
+describe('Sample project', () => {
+    it('sum should return 3', () => {
+        const result = sum(1, 2);
+        expect(result).toBe(3);
+    });
+
+    it('sum should return 0', () => {
+        const result = sum(1, -1);
+        expect(result).toBe(0);
+    });
+});
+```
+
+3. Install test runner named Karma with Chrome launcher and Jasmin plugin:
+
+```
+npm install --save-dev karma karma-jasmine karma-chrome-launcher
+```
+
+4. Create karma configuration file:
+
+karma.conf.js
+```
+module.exports = config => {
+    config.set({
+        basePath: './js',
+        frameworks: ['jasmine'],
+        files: [
+            '**/*.js'
+        ],
+        exclude: [
+            'main.js'
+        ],
+        preprocessors: {},
+        reporters: ['progress'],
+        port: 9876,
+        logLevel: config.LOG_INFO,
+        autoWatch: true,
+        browsers: ['Chrome'],
+        singleRun: false,
+        concurrency: Infinity
+    });
+};
+```
+
+5. Add test command into `package.json` file:
+
+```
+"scripts": {
+  "test": "karma start karma.conf.js"
+}
+```
+
+6. Run tests:
+
+```
+npm run test
+```
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