diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 000000000..70bee2cd4
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,132 @@
+name: Timber Tests
+
+on:
+  push:
+    branches:
+      - '*'
+  pull_request:
+    types: [opened, synchronize, ready_for_review]
+
+jobs:
+  phpunit:
+    runs-on: ubuntu-latest
+
+    services:
+      mysql:
+        image: mariadb:latest
+        env:
+          MYSQL_ALLOW_EMPTY_PASSWORD: true
+          MYSQL_ROOT_PASSWORD:
+          MYSQL_DATABASE: wordpress_test
+        ports:
+          - 3306
+        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
+
+    continue-on-error: ${{ matrix.experimental == true }}
+    strategy:
+
+      fail-fast: false
+      matrix:
+        php: ['7.4']
+        wp: ['5.3.6', 'latest']
+        multisite: ['0', '1']
+        dependency-version: [prefer-stable] # prefer-lowest
+        webp: [false]
+        coverage: [false]
+        extensions: ['gd']
+        include:
+          # WP Trunk
+          - php: '7.4'
+            wp: 'trunk'
+            dependency-version: 'prefer-stable'
+            multisite: '0'
+            experimental: true
+          # PHP with Imagick
+          - php: '7.4'
+            wp: 'latest'
+            dependency-version: 'prefer-stable'
+            multisite: '0'
+            extensions: 'imagick'
+          # Coverage
+          - php: '7.4'
+            wp: 'latest'
+            dependency-version: 'prefer-stable'
+            multisite: '0'
+            coverage: true
+
+    name: PHP ${{ matrix.php }} ${{ matrix.extensions == 'imagick' && ' (Imagick)' || '' }}${{ matrix.coverage && ' (with coverage)' || '' }} ${{ matrix.webp && ' (webp)' || '' }} | WP ${{ matrix.wp }}${{ matrix.multisite == 1 && ' (MS)' || '' }} | ${{ matrix.dependency-version }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: ${{ matrix.coverage && 'pcov' || 'none' }}
+          tools: composer:v2
+          extensions: curl, date, dom, iconv, json, libxml, mysql, ${{ matrix.extensions }}
+          ini-values: pcov.directory=lib
+
+      - name: Shutdown default MySQL service
+        run: sudo service mysql stop
+
+      - name: Verify MariaDB connection
+        run: |
+          while ! mysqladmin ping -h"127.0.0.1" -P"${{ job.services.mysql.ports[3306] }}" --silent; do
+            sleep 1
+          done
+
+      - name: Setup problem matchers for PHP
+        run: echo "::add-matcher::${{ runner.tool_cache }}/php.json"
+
+      - name: Setup problem matchers for PHPUnit
+        run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+
+      - name: Get composer cache directory
+        id: composer-cache
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache composer dependencies
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-${{ matrix.dependency-version }}-${{ matrix.php }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-${{ matrix.dependency-version }}-${{ matrix.php }}-composer-
+
+      - name: Install composer dependencies
+        run: composer update --${{ matrix.dependency-version }} --prefer-dist --no-progress --no-interaction
+
+      - name: Install tests
+        run: bash bin/install-wp-tests.sh wordpress_test root '' 127.0.0.1:${{ job.services.mysql.ports['3306'] }} ${{ matrix.wp }} true
+
+      - name: Setup PCOV
+        if: ${{ matrix.coverage == true }}
+        run: |
+          composer require --dev --ignore-platform-reqs pcov/clobber
+          vendor/bin/pcov clobber
+
+      - name: Run tests
+        if: ${{ !matrix.webp }}
+        run: vendor/bin/phpunit -c phpunit-nocover.xml --verbose --colors=always
+        env:
+          WP_MULTISITE: ${{ matrix.multisite }}
+
+      - name: Run tests with coverage
+        if: ${{ matrix.coverage == true }}
+        run: |
+          vendor/bin/phpunit -c phpunit.xml --verbose --colors=always
+
+      - name: Upload coverage results to Coveralls
+        if: ${{ matrix.coverage == true }}
+        env:
+          COVERALLS_REPO_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          composer global require php-coveralls/php-coveralls
+          php-coveralls --coverage_clover=build/logs/clover.xml -v
+
+      - name: Run webp tests
+        if: ${{ matrix.webp }}
+        run: vendor/phpunit/phpunit/phpunit -c phpunit.xml --verbose ./tests/test-timber-image-towebp.php
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 004632778..000000000
--- a/.travis.yml
+++ /dev/null
@@ -1,120 +0,0 @@
-# TravisCI configuration for timber/timber
-
-os: linux
-
-dist: bionic
-
-services: mysql
-
-language: php
-
-addons:
-  apt:
-    packages:
-      - libwebp-dev
-      - apt-transport-https
-      - apt-utils
-
-php:
-  - 7.2
-
-env:
-  global:
-    - TMPDIR=/tmp
-    - COVERALLS_PARALLEL=true
-  jobs:
-    - WP_VERSION=4.9.8 WP_MULTISITE=0 
-    - WP_VERSION=4.9.8 WP_MULTISITE=1
-    - WP_VERSION=latest WP_MULTISITE=0
-    - WP_VERSION=latest WP_MULTISITE=1
-
-jobs:
-  include:
-    - name: "Coverage: WP 4.9 on PHP 5.6"
-      php: 5.6
-      dist: xenial
-      env: WP_VERSION=4.9.8 WP_MULTISITE=0 PREFER_LOWEST="--prefer-lowest --prefer-stable"
-      before_install: skip
-      install:
-        - bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
-        - composer update $PREFER_LOWEST --prefer-source
-        - composer require --dev 'satooshi/php-coveralls:1.0.*'
-      script:
-        - mkdir -p build/logs
-        - vendor/phpunit/phpunit/phpunit -c phpunit.xml --verbose --coverage-clover build/logs/clover.xml
-      after_success:
-        - vendor/bin/coveralls -v
-    - name: "Coverage: ImageMagick extension on PHP 7.4"
-      php: 7.4
-      env: WP_VERSION=latest WP_MULTISITE=0
-      before_install:
-        - phpenv config-rm xdebug.ini
-        - yes '' | pecl install pcov
-        # Install imagick PHP extension
-        - pear config-set preferred_state beta
-        - pecl channel-update pecl.php.net
-        - yes '' | pecl install imagick
-      install:
-        - bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
-        - composer update $PREFER_LOWEST --prefer-source
-        - composer require --dev 'pcov/clobber:^2.0'
-        - vendor/bin/pcov clobber
-        - composer require --dev 'satooshi/php-coveralls:1.0.*'
-      script:
-        - mkdir -p build/logs
-        - vendor/phpunit/phpunit/phpunit -c phpunit.xml --verbose --coverage-clover build/logs/clover.xml
-      after_success:
-        - vendor/bin/coveralls -v
-    - name: "Coverage: WP multisite on PHP 7.4"
-      php: 7.4
-      env: WP_VERSION=latest WP_MULTISITE=1
-      before_install:
-        - phpenv config-rm xdebug.ini
-        - yes '' | pecl install pcov
-      install:
-        - bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
-        - composer update $PREFER_LOWEST --prefer-source
-        - composer require --dev 'pcov/clobber:^2.0'
-        - vendor/bin/pcov clobber
-        - composer require --dev 'satooshi/php-coveralls:1.0.*'
-      script:
-        - mkdir -p build/logs
-        - vendor/phpunit/phpunit/phpunit -c phpunit.xml --verbose --coverage-clover build/logs/clover.xml
-      after_success:
-        - vendor/bin/coveralls -v
-    - name: "WebP support on PHP 7.4"
-      php: 7.4
-      env: WP_VERSION=latest WP_MULTISITE=0
-      before_install:
-        # Install PHP with WebP support
-        - LC_ALL=C.UTF-8 sudo add-apt-repository -y ppa:ondrej/php
-        - sudo apt-get update
-        - sudo apt-get install -y "php${TRAVIS_PHP_VERSION}-cli" "php${TRAVIS_PHP_VERSION}-gd" "php${TRAVIS_PHP_VERSION}-xml" "php${TRAVIS_PHP_VERSION}-mysql"
-        - export PATH="/usr/bin:${PATH}"
-        - php --rf imagewebp
-      install:
-        - bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
-        - composer update --prefer-source
-      script:
-        - vendor/phpunit/phpunit/phpunit -c phpunit.xml --verbose ./tests/test-timber-image-towebp.php
-      after_success: skip
-
-cache:
-  directories:
-    - "${HOME}/.composer/cache"
-
-before_install:
-  # phpenv config-add myconfig.ini --with-webp-dir
-  - phpenv config-rm xdebug.ini
-
-install:
-  - bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
-  - composer update $PREFER_LOWEST --prefer-source
-
-script:
-  - vendor/phpunit/phpunit/phpunit -c phpunit-nocover.xml --verbose
-
-notifications:
-  webhooks:
-    # https://docs.coveralls.io/parallel-build-webhook
-    - 'https://coveralls.io/webhook'
diff --git a/bin/install-wp-tests.sh b/bin/install-wp-tests.sh
old mode 100644
new mode 100755
index b54cb1236..ee05775c8
--- a/bin/install-wp-tests.sh
+++ b/bin/install-wp-tests.sh
@@ -13,17 +13,13 @@ WP_VERSION=${5-latest}
 SKIP_DB_CREATE=${6-false}
 
 TMPDIR=${TMPDIR-/tmp}
+TMPDIR=$(echo $TMPDIR | sed -e "s/\/$//")
 WP_TESTS_DIR=${WP_TESTS_DIR-$TMPDIR/wordpress-tests-lib}
 WP_CORE_DIR=${WP_CORE_DIR-$TMPDIR/wordpress}
 
-# think 'untrailingslashit(), but in bash"
-TMPDIR=$(echo $TMPDIR | sed -e "s/\/$//")
-WP_TESTS_DIR=$(echo $WP_TESTS_DIR | sed -e "s/\/$//")
-WP_CORE_DIR=$(echo $WP_CORE_DIR | sed -e "s/\/$//")
-
 download() {
     if [ `which curl` ]; then
-        curl -sL "$1" > "$2";
+        curl -s "$1" > "$2";
     elif [ `which wget` ]; then
         wget -nv -O "$2" "$1"
     fi
@@ -66,12 +62,12 @@ install_wp() {
 	mkdir -p $WP_CORE_DIR
 
 	if [[ $WP_VERSION == 'nightly' || $WP_VERSION == 'trunk' ]]; then
-		mkdir -p $TMPDIR/wordpress-nightly
-		download https://wordpress.org/nightly-builds/wordpress-latest.zip  $TMPDIR/wordpress-nightly/wordpress-nightly.zip
-		unzip -q $TMPDIR/wordpress-nightly/wordpress-nightly.zip -d $TMPDIR/wordpress-nightly/
-		mv $TMPDIR/wordpress-nightly/wordpress/* $WP_CORE_DIR
+		mkdir -p $TMPDIR/wordpress-trunk
+		rm -rf $TMPDIR/wordpress-trunk/*
+		svn export --quiet https://core.svn.wordpress.org/trunk $TMPDIR/wordpress-trunk/wordpress
+		mv $TMPDIR/wordpress-trunk/wordpress/* $WP_CORE_DIR
 	else
-		if [[ $WP_VERSION == 'latest' ]]; then
+		if [ $WP_VERSION == 'latest' ]; then
 			local ARCHIVE_NAME='latest'
 		elif [[ $WP_VERSION =~ [0-9]+\.[0-9]+ ]]; then
 			# https serves multiple offers, whereas http serves single.
@@ -111,8 +107,9 @@ install_test_suite() {
 	if [ ! -d $WP_TESTS_DIR ]; then
 		# set up testing suite
 		mkdir -p $WP_TESTS_DIR
-		svn co --quiet https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/includes/ $WP_TESTS_DIR/includes
-		svn co --quiet https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/data/ $WP_TESTS_DIR/data
+		rm -rf $WP_TESTS_DIR/{includes,data}
+		svn export --quiet --ignore-externals https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/includes/ $WP_TESTS_DIR/includes
+		svn export --quiet --ignore-externals https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/data/ $WP_TESTS_DIR/data
 	fi
 
 	if [ ! -f wp-tests-config.php ]; then
@@ -120,6 +117,7 @@ install_test_suite() {
 		# remove all forward slashes in the end
 		WP_CORE_DIR=$(echo $WP_CORE_DIR | sed "s:/\+$::")
 		sed $ioption "s:dirname( __FILE__ ) . '/src/':'$WP_CORE_DIR/':" "$WP_TESTS_DIR"/wp-tests-config.php
+		sed $ioption "s:__DIR__ . '/src/':'$WP_CORE_DIR/':" "$WP_TESTS_DIR"/wp-tests-config.php
 		sed $ioption "s/youremptytestdbnamehere/$DB_NAME/" "$WP_TESTS_DIR"/wp-tests-config.php
 		sed $ioption "s/yourusernamehere/$DB_USER/" "$WP_TESTS_DIR"/wp-tests-config.php
 		sed $ioption "s/yourpasswordhere/$DB_PASS/" "$WP_TESTS_DIR"/wp-tests-config.php
@@ -128,6 +126,23 @@ install_test_suite() {
 
 }
 
+recreate_db() {
+	shopt -s nocasematch
+	if [[ $1 =~ ^(y|yes)$ ]]
+	then
+		mysqladmin drop $DB_NAME -f --user="$DB_USER" --password="$DB_PASS"$EXTRA
+		create_db
+		echo "Recreated the database ($DB_NAME)."
+	else
+		echo "Leaving the existing database ($DB_NAME) in place."
+	fi
+	shopt -u nocasematch
+}
+
+create_db() {
+	mysqladmin create $DB_NAME --user="$DB_USER" --password="$DB_PASS"$EXTRA
+}
+
 install_db() {
 
 	if [ ${SKIP_DB_CREATE} = "true" ]; then
@@ -151,7 +166,14 @@ install_db() {
 	fi
 
 	# create database
-	mysqladmin create $DB_NAME --user="$DB_USER" --password="$DB_PASS"$EXTRA
+	if [ $(mysql --user="$DB_USER" --password="$DB_PASS"$EXTRA --execute='show databases;' | grep ^$DB_NAME$) ]
+	then
+		echo "Reinstalling will delete the existing test database ($DB_NAME)"
+		read -p 'Are you sure you want to proceed? [y/N]: ' DELETE_EXISTING_DB
+		recreate_db $DELETE_EXISTING_DB
+	else
+		create_db
+	fi
 }
 
 install_wp
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 6440da958..e19704ba4 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,30 +1,47 @@
 <?php
 
+if ( PHP_MAJOR_VERSION >= 8 ) {
+	echo "The scaffolded tests cannot currently be run on PHP 8.0+. See https://github.com/wp-cli/scaffold-command/issues/285" . PHP_EOL; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+	exit( 1 );
+}
+
 $_tests_dir = getenv( 'WP_TESTS_DIR' );
 
 if ( ! $_tests_dir ) {
-	$_tests_dir = rtrim( getenv( 'TMPDIR' ), '/' ) . '/wordpress-tests-lib';
+	$_tests_dir = rtrim( sys_get_temp_dir(), '/\\' ) . '/wordpress-tests-lib';
+}
+
+if ( ! file_exists( "{$_tests_dir}/includes/functions.php" ) ) {
+	echo "Could not find {$_tests_dir}/includes/functions.php, have you run bin/install-wp-tests.sh ?" . PHP_EOL; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+	exit( 1 );
 }
 
-require_once $_tests_dir . '/includes/functions.php';
+// Give access to tests_add_filter() function.
+require_once "{$_tests_dir}/includes/functions.php";
 
+/**
+ * Manually load the plugin being tested.
+ */
 function _manually_load_plugin() {
 	global $timber;
 
 	require dirname( __FILE__ ) . '/../vendor/autoload.php';
 	$timber = new \Timber\Timber();
+
 	require dirname( __FILE__ ) . '/../wp-content/plugins/advanced-custom-fields/acf.php';
-	require dirname( __FILE__ ) . '/../wp-content/plugins/co-authors-plus/co-authors-plus.php';
+	if ( file_exists( dirname( __FILE__ ) . '/../wp-content/plugins/co-authors-plus/co-authors-plus.php') ) {
+		include dirname( __FILE__ ) . '/../wp-content/plugins/co-authors-plus/co-authors-plus.php';
+	}
 }
 
 tests_add_filter( 'muplugins_loaded', '_manually_load_plugin' );
 
-require $_tests_dir . '/includes/bootstrap.php';
+// Start up the WP testing environment.
+require "{$_tests_dir}/includes/bootstrap.php";
 
 require_once __DIR__.'/Timber_UnitTestCase.php';
-require_once __DIR__.'/TimberImage_UnitTestCase.php';
-
-error_log('Use http://build.starter-theme.dev/ for testing with UI');
+require_once __DIR__.'/TimberAttachment_UnitTestCase.php';
+require_once __DIR__.'/timber-mock-classes.php';
 
 if ( !function_exists('is_post_type_viewable') ) {
 	function is_post_type_viewable( $post_type_object ) {