feat(tests): Add proper automated tests (#107)

In order to prevent functional regressions, let's renovate our automated tests and use a proper test runner: [Ava](https://github.com/avajs/ava).

Although Node.js 12 is needed by Ava to run tests, `pdfreader` still works with Node.js 8+.

.github/workflows/nodejs.yml

@@ -9,32 +9,52 @@ on:
       - master
 
 jobs:
-  check:
+  # Make sure that pdfreader can still run on old Node.js versions
+  old-node:
     runs-on: ubuntu-latest
-
     strategy:
       matrix:
         node-version: [8.x, 10.x]
+    steps:
+      - uses: actions/checkout@v1
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: npm ci # install dependencies
+      - run: npm run test:samples
 
+  # Prevent functional regressions on supported Node.js versions
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [12.x, 14.x, 16.x]
     steps:
       - uses: actions/checkout@v1
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v1
         with:
           node-version: ${{ matrix.node-version }}
-      - name: install deps
-        run: npm ci
-        env:
-          CI: true
+      - run: npm ci # install dependencies
       - run: npm test
-        env:
-          CI: true
+
+  # Checks that files are formatted consistently
+  formatting:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 16.x
+      - run: npm ci # install dependencies
       - run: npm run prettier:check
-        env:
-          CI: true
 
   release:
-    needs: check
+    needs:
+      - tests
+      - old-node
+      - formatting
     runs-on: ubuntu-latest
     steps:
       - name: Checkout

.nvmrc

@@ -1 +1 @@
-v10
+v16

README.md

@@ -15,9 +15,10 @@ Summary:
 - [Rule-based data extraction](#rule-based-data-extraction)
 - [Troubleshooting & FAQ](#troubleshooting--faq)
 
-## Installation, tests and CLI usage (make sure node v8 or v10)
+## Installation, tests and CLI usage
 
 ```sh
+nvm use # optional, to switch to the recommended version of Node.js
 npm install pdfreader
 cd node_modules/pdfreader
 npm test