Add unit tests for data parsing

The specified Arduino plotter protocol is quite flexible, which means there multiple possible data formats which might
be supplied by a user, all of which must be supported.

In order to be able to continue the development of the project with confidence that no regressions will be introduced,
good test coverage of the data formats is essential.

Tests are added here. A GitHub Actions workflow will automatically run the tests after every relevant change as well as
periodically to catch breakage that might result from external changes.

Author: per1234

.github/workflows/test-typescript-npm.yml

@@ -0,0 +1,73 @@
+name: Test TypeScript
+
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 10.x
+
+on:
+  push:
+    paths:
+      - ".github/workflows/test-typescript-npm.ya?ml"
+      - ".github/.?codecov.ya?ml"
+      - "dev/.?codecov.ya?ml"
+      - ".?codecov.ya?ml"
+      - "jest.config.js"
+      - "package.json"
+      - "package-lock.json"
+      - "tsconfig.json"
+      - "**.js"
+      - "**.jsx"
+      - "**.ts"
+      - "**.tsx"
+  pull_request:
+    paths:
+      - ".github/workflows/test-typescript-npm.ya?ml"
+      - "jest.config.js"
+      - "package.json"
+      - "package-lock.json"
+      - "tsconfig.json"
+      - "**.js"
+      - "**.jsx"
+      - "**.ts"
+      - "**.tsx"
+  schedule:
+    # Run periodically to catch breakage caused by external changes.
+    - cron: "0 13 * * WED"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  test:
+    runs-on: ${{ matrix.operating-system }}
+
+    strategy:
+      fail-fast: false
+
+      matrix:
+        operating-system:
+          - macos-latest
+          - ubuntu-latest
+          # The version of node-gyp used by this project (7.1.2) requires an older version of Visual Studio that is not
+          # available in the latest Windows GitHub Actions runner.
+          - windows-2019
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm run-script test
+
+      - name: Send unit test coverage to Codecov
+        if: runner.os == 'Linux'
+        uses: codecov/codecov-action@v3
+        with:
+          fail_ci_if_error: ${{ github.repository == 'arduino/arduino-serial-plotter-webapp' }}

README.md

@@ -1,5 +1,7 @@
 # Serial Plotter WebApp
 
+[![Test TypeScript status](https://github.com/arduino/arduino-serial-plotter-webapp/actions/workflows/test-typescript-npm.yml/badge.svg)](https://github.com/arduino/arduino-serial-plotter-webapp/actions/workflows/test-typescript-npm.yml)
+
 This is a SPA that receives data points over WebSocket and prints graphs. The purpose is to provide a visual and live representation of data printed to the Serial Port.
 
 The application is designed to be as agnostic as possible regarding how and where it runs. For this reason, it accepts different settings when it's launched in order to configure the look&feel and the connection parameters.
@@ -162,6 +164,7 @@ These are sent to the middleware to be stored and propagated to other clients.
 ## Development
 
 - `npm i` to install dependencies
+- `npm test` to run automated tests
 - `npm start` to run the application in development mode @ [http://localhost:3000](http://localhost:3000)
 
 ## Deployment

jest.config.js

@@ -0,0 +1,12 @@
+/*
+ * For a detailed explanation regarding each configuration property, visit:
+ * https://jestjs.io/docs/en/configuration.html
+ */
+
+module.exports = {
+  collectCoverage: true,
+  coverageDirectory: "coverage",
+  coverageReporters: ["lcov"],
+  preset: "ts-jest",
+  testEnvironment: "node",
+};

package-lock.json

@@ -6,7 +6,7 @@
   "scripts": {
     "start": "react-scripts start",
     "build": "react-scripts build",
-    "test": "react-scripts test",
+    "test": "jest",
     "eject": "react-scripts eject"
   },
   "files": [
@@ -49,6 +49,7 @@
     "chartjs-plugin-streaming": "^2.0.0",
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-prettier": "^4.0.0",
+    "jest": "^26.6.0",
     "luxon": "^2.1.0",
     "node-sass": "^6.0.1",
     "prettier": "^2.4.1",
@@ -60,6 +61,7 @@
     "react-scripts": "4.0.3",
     "react-select": "^5.1.0",
     "react-switch": "^6.0.0",
+    "ts-jest": "^26.5.6",
     "typescript": "^4.4.3",
     "web-vitals": "^1.1.2",
     "worker-loader": "^3.0.8"