CI: switch to GitHub Actions

.gitattributes

@@ -1,6 +1,6 @@
 /.gitattributes export-ignore
 /.gitignore export-ignore
-/.travis.yml export-ignore
+/.github/ export-ignore
 /CONTRIBUTING.md export-ignore
 /fixtures/ export-ignore
 /phpunit.xml.dist export-ignore

.github/workflows/ci.yml

@@ -0,0 +1,58 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  # Allow manually triggering the workflow.
+  workflow_dispatch:
+
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check_composer:
+    name: Check composer.json
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.0'
+          coverage: none
+
+      - name: Validate composer.json
+        run: composer validate --strict --no-check-lock
+
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php: ['7.3', '7.4', '8.0', '8.1']
+
+    name: PHP ${{ matrix.php }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          ini-values: zend.assertions=1, error_reporting=-1, display_errors=On
+          coverage: xdebug
+
+      # Install dependencies and handle caching in one go.
+      # @link https://github.com/marketplace/actions/install-composer-dependencies
+      - name: Install Composer dependencies
+        uses: "ramsey/composer-install@v1"
+
+      - name: Execute Unit Tests
+        run: vendor/bin/phpunit --coverage-text

README.md

@@ -1,6 +1,6 @@
 # Prophecy
 
-[![Build Status](https://travis-ci.org/phpspec/prophecy-phpunit.png?branch=master)](https://travis-ci.org/phpspec/prophecy-phpunit)
+[![Build Status](https://github.com/phpspec/prophecy-phpunit/actions/workflows/ci.yml/badge.svg)](https://github.com/phpspec/prophecy-phpunit/actions/workflows/ci.yml)
 
 Prophecy PhpUnit integrates the [Prophecy](https://github.com/phpspec/prophecy) mocking
 library with [PHPUnit](https://phpunit.de) to provide an easier mocking in your testsuite.