workflows: add test workflow

Author: GioeleBucci

.github/workflows/test-runner.yml

@@ -0,0 +1,26 @@
+name: Test Runner
+
+on:
+  push:
+    branches:
+      - main  
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Set up JDK
+      uses: actions/setup-java@v2
+      with:
+        distribution: 'adopt'
+        java-version: '17'
+
+    - name: Run tests
+      run: ./gradlew test

README.md

@@ -1,5 +1,9 @@
 # TBOOOP! A demake of The Binding of Isaac
 
+<p align="center">
+  <img src="https://github.com/GioeleBucci/TBOOOP/actions/workflows/test-runner.yml/badge.svg" alt="Tests">
+</p>
+
 <p align="center">
   <img src="https://imgur.com/u0BDjx7.png">
 </p>