diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
new file mode 100644
index 0000000..0990819
--- /dev/null
+++ b/.github/workflows/unit-tests.yml
@@ -0,0 +1,39 @@
+name: Unit Tests
+
+on: [push, pull_request]
+
+jobs:
+  run:
+    runs-on: ${{ matrix.operating-system }}
+    strategy:
+      matrix:
+        operating-system: [ubuntu-latest]
+        php-versions: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
+    name: PHP ${{ matrix.php-versions }}
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          coverage: none
+
+      - name: Get composer cache directory
+        id: composer-cache
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache dependencies
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
+          restore-keys: ${{ runner.os }}-composer-
+
+      - name: Install dependencies
+        run: composer install --no-interaction --prefer-dist --no-suggest --no-progress
+
+      - name: Run test suite
+        run: composer test
diff --git a/.gitignore b/.gitignore
index c6d1959..384aae8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,7 @@
-composer.lock
 tests/coverage
 vendor
+.phpunit.result.cache
+
+# The composer.lock file is not needed, as this is a library whose dependencies
+# will depend on the version of PHP being used.
+composer.lock
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index af2584a..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,27 +0,0 @@
-language: php
-
-php:
-  - 7.0
-  - 7.1
-  - 7.2
-  - 7.3
-  - 7.4
-
-sudo: false
-
-env:
-  matrix:
-    - PREFER_LOWEST="--prefer-lowest --prefer-stable"
-    - PREFER_LOWEST=""
-
-install:
-  - wget https://github.com/php-coveralls/php-coveralls/releases/download/v1.0.0/coveralls.phar
-  - chmod +x coveralls.phar
-  - composer update --no-interaction --prefer-dist $PREFER_LOWEST
-
-script:
-  - mkdir -p build/logs
-  - vendor/bin/phpunit --coverage-clover build/logs/clover.xml
-
-after_success:
-  - travis_retry php coveralls.phar
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 042a879..80ff798 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,24 +1,34 @@
 # Changelog
+
 All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [1.3.1] — 2020-01-14
+
+* Fix PHPUnit warnings regarding `assertContains()` and `assertRegExp()`. Props [@jakobbuis](https://github.com/jakobbuis) ([#20], [#27], [#28])
+* Refactor the internal test scaffolding, including a move from Travis CI to GitHub Actions. Props [@peter279k](https://github.com/peter279k) for the assist with GitHub Actions ([#24])
+* Added PHP 8.0 support ([#26])
+
 ## [1.3.0] — 2020-01-27
 
-* Replace `zendframework/zend-dom` with `laminas/laminas-dom` ([#16]).
-* Update Composer dependencies, add a `composer test` script ([#15]).
+* Replace `zendframework/zend-dom` with `laminas/laminas-dom` ([#16])
+* Update Composer dependencies, add a `composer test` script ([#15])
+
 
 ## [1.2.0] - 2018-03-27
 
 * Bumped the minimum version of zendframework/zend-dom to 2.7, which includes a fix for attribute values that include spaces ([#13]).
 
+
 ## [1.1.0] - 2018-01-14
 
-* Added the `assertElementContains()`, `assertElementNotContains()`, `assertElementRegExp()`, and `assertElementNotRegExp()` assertions, for verifying the contents of elements that match the given DOM query ([#6]).
-* Moved the `Tests` namespace into a development-only autoloader, to prevent them from potentially being included in projects using this library ([#7]).
-* [Based on this article by Martin Hujer](https://blog.martinhujer.cz/17-tips-for-using-composer-efficiently/#tip-%236%3A-put-%60composer.lock%60-into-%60.gitignore%60-in-libraries), remove the `composer.lock` file from the library ([#8]).
-* _Lower_ the minimum version of [zendframework/zend-dom](https://packagist.org/packages/zendframework/zend-dom) to 2.2.5 for maximum portability ([#9]).
+* Added the `assertElementContains()`, `assertElementNotContains()`, `assertElementRegExp()`, and `assertElementNotRegExp()` assertions, for verifying the contents of elements that match the given DOM query ([#6])
+* Moved the `Tests` namespace into a development-only autoloader, to prevent them from potentially being included in projects using this library ([#7])
+* [Based on this article by Martin Hujer](https://blog.martinhujer.cz/17-tips-for-using-composer-efficiently/#tip-%236%3A-put-%60composer.lock%60-into-%60.gitignore%60-in-libraries), remove the `composer.lock` file from the library ([#8])
+* _Lower_ the minimum version of [zendframework/zend-dom](https://packagist.org/packages/zendframework/zend-dom) to 2.2.5 for maximum portability ([#9])
+
 
 ## [1.0.0] - 2017-10-24
 
@@ -26,6 +36,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 
 [Unreleased]: https://github.com/stevegrunwell/phpunit-markup-assertions/compare/master...develop
+[1.3.1]: https://github.com/stevegrunwell/phpunit-markup-assertions/releases/tag/v1.3.1
 [1.3.0]: https://github.com/stevegrunwell/phpunit-markup-assertions/releases/tag/v1.3.0
 [1.2.0]: https://github.com/stevegrunwell/phpunit-markup-assertions/releases/tag/v1.2.0
 [1.1.0]: https://github.com/stevegrunwell/phpunit-markup-assertions/releases/tag/v1.1.0
@@ -37,3 +48,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 [#13]: https://github.com/stevegrunwell/phpunit-markup-assertions/issues/13
 [#15]: https://github.com/stevegrunwell/phpunit-markup-assertions/pull/15
 [#16]: https://github.com/stevegrunwell/phpunit-markup-assertions/issues/16
+[#20]: https://github.com/stevegrunwell/phpunit-markup-assertions/pull/20
+[#24]: https://github.com/stevegrunwell/phpunit-markup-assertions/pull/24
+[#26]: https://github.com/stevegrunwell/phpunit-markup-assertions/pull/26
+[#27]: https://github.com/stevegrunwell/phpunit-markup-assertions/pull/27
+[#28]: https://github.com/stevegrunwell/phpunit-markup-assertions/pull/28
diff --git a/README.md b/README.md
index 8c66e88..7a5a113 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,6 @@
 # PHPUnit Markup Assertions
 
-[![Build Status](https://travis-ci.org/stevegrunwell/phpunit-markup-assertions.svg?branch=develop)](https://travis-ci.org/stevegrunwell/phpunit-markup-assertions)
-[![Coverage Status](https://coveralls.io/repos/github/stevegrunwell/phpunit-markup-assertions/badge.svg?branch=develop)](https://coveralls.io/github/stevegrunwell/phpunit-markup-assertions?branch=develop)
+![Build Status](https://github.com/stevegrunwell/phpunit-markup-assertions/workflows/Unit%20Tests/badge.svg)
 [![GitHub release](https://img.shields.io/github/release/stevegrunwell/phpunit-markup-assertions.svg)](https://github.com/stevegrunwell/phpunit-markup-assertions/releases)
 
 This library introduces the `MarkupAssertionsTrait` trait for use in [PHPUnit](https://phpunit.de) tests.
diff --git a/composer.json b/composer.json
index c30d59c..c8d2ae6 100644
--- a/composer.json
+++ b/composer.json
@@ -15,10 +15,11 @@
         "source": "https://github.com/stevegrunwell/phpunit-markup-assertions/"
     },
     "require": {
-        "laminas/laminas-dom": "^2.7"
+        "php": "^5.6 || ^7.0 || ^8.0",
+        "laminas/laminas-dom": "~2.7.2 || ^2.8"
     },
     "require-dev": {
-        "phpunit/phpunit": "^6.0"
+        "symfony/phpunit-bridge": "^5.2"
     },
     "autoload": {
         "psr-4": {
@@ -32,10 +33,10 @@
     },
     "scripts": {
         "test": [
-            "phpunit"
+            "simple-phpunit --testdox"
         ],
         "test-coverage": [
-            "phpunit --coverage-html=tests/coverage"
+            "phpdbg -qrr -d memory_limit=-1 ./vendor/bin/simple-phpunit --coverage-html=tests/coverage --colors=always"
         ]
     },
     "scripts-descriptions": {
@@ -44,7 +45,6 @@
     },
     "config": {
         "preferred-install": "dist",
-        "sort-packages": true,
-        "optimize-autoloader": true
+        "sort-packages": true
     }
 }
diff --git a/src/MarkupAssertionsTrait.php b/src/MarkupAssertionsTrait.php
index 14767a7..2af9fe6 100644
--- a/src/MarkupAssertionsTrait.php
+++ b/src/MarkupAssertionsTrait.php
@@ -114,7 +114,11 @@ public function assertNotHasElementWithAttributes($attributes = [], $output = ''
      */
     public function assertElementContains($contents, $selector = '', $output = '', $message = '')
     {
-        $this->assertContains(
+        $method = method_exists($this, 'assertStringContainsString')
+            ? 'assertStringContainsString'
+            : 'assertContains';
+
+        $this->$method(
             $contents,
             $this->getInnerHtmlOfMatchedElements($output, $selector),
             $message
@@ -133,7 +137,11 @@ public function assertElementContains($contents, $selector = '', $output = '', $
      */
     public function assertElementNotContains($contents, $selector = '', $output = '', $message = '')
     {
-        $this->assertNotContains(
+        $method = method_exists($this, 'assertStringNotContainsString')
+            ? 'assertStringNotContainsString'
+            : 'assertNotContains';
+
+        $this->$method(
             $contents,
             $this->getInnerHtmlOfMatchedElements($output, $selector),
             $message
@@ -152,7 +160,11 @@ public function assertElementNotContains($contents, $selector = '', $output = ''
      */
     public function assertElementRegExp($regexp, $selector = '', $output = '', $message = '')
     {
-        $this->assertRegExp(
+        $method = method_exists($this, 'assertMatchesRegularExpression')
+            ? 'assertMatchesRegularExpression'
+            : 'assertRegExp';
+
+        $this->$method(
             $regexp,
             $this->getInnerHtmlOfMatchedElements($output, $selector),
             $message
@@ -171,7 +183,11 @@ public function assertElementRegExp($regexp, $selector = '', $output = '', $mess
      */
     public function assertElementNotRegExp($regexp, $selector = '', $output = '', $message = '')
     {
-        $this->assertNotRegExp(
+        $method = method_exists($this, 'assertDoesNotMatchRegularExpression')
+            ? 'assertDoesNotMatchRegularExpression'
+            : 'assertNotRegExp';
+
+        $this->$method(
             $regexp,
             $this->getInnerHtmlOfMatchedElements($output, $selector),
             $message
diff --git a/tests/MarkupAssertionsTraitTest.php b/tests/MarkupAssertionsTraitTest.php
index a8ef54c..4692388 100644
--- a/tests/MarkupAssertionsTraitTest.php
+++ b/tests/MarkupAssertionsTraitTest.php
@@ -5,65 +5,73 @@
 use PHPUnit\Framework\AssertionFailedError;
 use PHPUnit\Framework\RiskyTestError;
 use PHPUnit\Framework\TestCase;
-use ReflectionMethod;
-use Tests\TestFiles\TestCaseWithMarkupAssertions;
+use SteveGrunwell\PHPUnit_Markup_Assertions\MarkupAssertionsTrait;
 
+/**
+ * @covers SteveGrunwell\PHPUnit_Markup_Assertions\MarkupAssertionsTrait
+ */
 class MarkupAssertionsTraitTest extends TestCase
 {
-    /**
-     * Holds a clean instance of TestCaseWithMarkupAssertions.
-     *
-     * @var TestCaseWithMarkupAssertions
-     */
-    protected $testcase;
-
-    public function setUp()
-    {
-        $this->testcase = new TestCaseWithMarkupAssertions;
-    }
+    use MarkupAssertionsTrait;
 
     /**
-     * @dataProvider selectorVariantProvider()
+     * @test
+     * @testdox assertContainsSelector() should find matching selectors
+     * @dataProvider provideSelectorVariants
      */
-    public function testAssertContainsSelector($selector)
+    public function assertContainsSelector_should_find_matching_selectors($selector)
     {
-        $this->testcase->assertContainsSelector(
+        $this->assertContainsSelector(
             $selector,
             '<a href="https://example.com" id="my-link" class="link another-class">Example</a>'
         );
     }
 
-    public function testAssertContainsWithMultipleMatches()
+    /**
+     * @test
+     * @testdox assertContainsSelector() should pick up multiple instances of a selector
+     */
+    public function assertContainsSelector_should_pick_up_multiple_instances()
     {
-        $this->testcase->assertContainsSelector(
+        $this->assertContainsSelector(
             'a',
             '<a href="#home">Home</a> | <a href="#about">About</a> | <a href="#contact">Contact</a>'
         );
     }
 
     /**
-     * @dataProvider selectorVariantProvider()
+     * @test
+     * @testdox assertNotContainsSelector() should verify that the given selector does not exist
+     * @dataProvider provideSelectorVariants
      */
-    public function testAssertNotContainsSelector($selector)
+    public function assertNotContainsSelector_should_verify_that_the_given_selector_does_not_exist($selector)
     {
-        $this->testcase->assertNotContainsSelector(
+        $this->assertNotContainsSelector(
             $selector,
             '<h1 id="page-title" class="foo bar">This element has little to do with the link.</h1>'
         );
     }
 
-    public function testAssertSelectorCount()
+    /**
+     * @test
+     * @testdox assertSelectorCount() should count the instances of a selector
+     */
+    public function assertSelectorCount_should_count_the_number_of_instances()
     {
-        $this->testcase->assertSelectorCount(
+        $this->assertSelectorCount(
             3,
             'li',
             '<ul><li>1</li><li>2</li><li>3</li></ul>'
         );
     }
 
-    public function testAssertHasElementWithAttributes()
+    /**
+     * @test
+     * @testdox assertHasElementWithAttributes() should find an element with the given attributes
+     */
+    public function assertHasElementWithAttributes_should_find_elements_with_matching_attributes()
     {
-        $this->testcase->assertHasElementWithAttributes(
+        $this->assertHasElementWithAttributes(
             [
                 'type' => 'email',
                 'value' => 'test@example.com',
@@ -73,11 +81,13 @@ public function testAssertHasElementWithAttributes()
     }
 
     /**
-     * @link https://github.com/stevegrunwell/phpunit-markup-assertions/issues/13
+     * @test
+     * @testdox assertHasElementWithAttributes() should be able to parse spaces in attribute values
+     * @ticket https://github.com/stevegrunwell/phpunit-markup-assertions/issues/13
      */
-    public function testAssertHasElementWithAttributesWithSpacesInTheAttributeValue()
+    public function assertHasElementWithAttributes_should_be_able_to_handle_spaces()
     {
-        $this->testcase->assertHasElementWithAttributes(
+        $this->assertHasElementWithAttributes(
             [
                 'data-attr' => 'foo bar baz',
             ],
@@ -85,9 +95,13 @@ public function testAssertHasElementWithAttributesWithSpacesInTheAttributeValue(
         );
     }
 
-    public function testAssertNotHasElementWithAttributes()
+    /**
+     * @test
+     * @testdox assertNotHasElementWithAttributes() should ensure no element has the provided attributes
+     */
+    public function assertNotHasElementWithAttributes_should_find_no_elements_with_matching_attributes()
     {
-        $this->testcase->assertNotHasElementWithAttributes(
+        $this->assertNotHasElementWithAttributes(
             [
                 'type' => 'email',
                 'value' => 'test@example.com',
@@ -96,30 +110,42 @@ public function testAssertNotHasElementWithAttributes()
         );
     }
 
-    public function testAssertElementContains()
+    /**
+     * @test
+     * @testdox assertElementContains() should be able to search for a selector
+     */
+    public function assertElementContains_can_match_a_selector()
     {
-        $this->testcase->assertElementContains(
+        $this->assertElementContains(
             'ipsum',
             '#main',
             '<header>Lorem ipsum</header><div id="main">Lorem ipsum</div>'
         );
     }
 
-    public function testAssertElementContainsMultipleSelectors()
+    /**
+     * @test
+     * @testdox assertElementContains() should be able to chain multiple selectors
+     */
+    public function assertElementContains_can_chain_multiple_selectors()
     {
-        $this->testcase->assertElementContains(
+        $this->assertElementContains(
             'ipsum',
             '#main .foo',
             '<div id="main"><span class="foo">Lorem ipsum</span></div>'
         );
     }
 
-    public function testAssertElementContainsScopesToSelector()
+    /**
+     * @test
+     * @testdox assertElementContains() should scope text to the selected element
+     */
+    public function assertElementContains_should_scope_matches_to_selector()
     {
         $this->expectException(AssertionFailedError::class);
         $this->expectExceptionMessage('The #main div does not contain the string "ipsum".');
 
-        $this->testcase->assertElementContains(
+        $this->assertElementContains(
             'ipsum',
             '#main',
             '<header>Lorem ipsum</header><div id="main">Foo bar baz</div>',
@@ -127,78 +153,102 @@ public function testAssertElementContainsScopesToSelector()
         );
     }
 
-    public function testAssertElementNotContains()
+    /**
+     * @test
+     * @testdox assertElementNotContains() should be able to search for a selector
+     */
+    public function assertElementNotContains_can_match_a_selector()
     {
-        $this->testcase->assertElementNotContains(
+        $this->assertElementNotContains(
             'ipsum',
             '#main',
             '<header>Foo bar baz</header><div id="main">Some string</div>'
         );
     }
 
-    public function testAssertElementRegExp()
+    /**
+     * @test
+     * @testdox assertElementRegExp() should use regular expression matching
+     */
+    public function assertElementRegExp_should_use_regular_expression_matching()
     {
-        $this->testcase->assertElementRegExp(
+        $this->assertElementRegExp(
             '/[A-Z0-9-]+/',
             '#main',
             '<header>Lorem ipsum</header><div id="main">ABC123</div>'
         );
     }
 
-    public function testAssertElementRegExpWithNestedElements()
+    /**
+     * @test
+     * @testdox assertElementRegExp() should be able to search for nested contents
+     */
+    public function assertElementRegExp_should_be_able_to_match_nested_contents()
     {
-        $this->testcase->assertElementRegExp(
+        $this->assertElementRegExp(
             '/[A-Z]+/',
             '#main',
             '<header>Lorem ipsum</header><div id="main"><span>ABC</span></div>'
         );
     }
 
+    /**
+     * @test
+     * @testdox assertElementNotRegExp() should use regular expression matching
+     */
     public function testAssertElementNotRegExp()
     {
-        $this->testcase->assertElementNotRegExp(
+        $this->assertElementNotRegExp(
             '/[0-9-]+/',
             '#main',
             '<header>Foo bar baz</header><div id="main">ABC</div>'
         );
     }
 
+
     /**
-     * @dataProvider attributeProvider()
+     * @test
+     * @testdox flattenAttributeArray() should flatten an array of attributes
+     * @dataProvider provideAttributes
      */
-    public function testFlattenAttributeArray($attributes, $expected)
+    public function flattenArrayAttribute_should_flatten_arrays_of_attributes($attributes, $expected)
     {
-        $method = new ReflectionMethod($this->testcase, 'flattenAttributeArray');
+        $method = new \ReflectionMethod($this, 'flattenAttributeArray');
         $method->setAccessible(true);
 
-        $this->assertEquals($expected, $method->invoke($this->testcase, $attributes));
+        $this->assertSame($expected, $method->invoke($this, $attributes));
     }
 
     /**
-     * @expectedException PHPUnit\Framework\RiskyTestError
+     * @test
+     * @testdox flattenAttributeArray() should throw a RiskyTestError if the array is empty
+     * @dataProvider provideAttributes
      */
-    public function testFlattenAttributeArrayThrowsRiskyTestError()
+    public function flattenAttributeArray_should_throw_a_RiskyTestError_if_given_an_empty_array()
     {
-        $method = new ReflectionMethod($this->testcase, 'flattenAttributeArray');
-        $method->setAccessible(true);
+        $this->expectException(RiskyTestError::class);
 
-        $method->invoke($this->testcase, []);
+        $method = new \ReflectionMethod($this, 'flattenAttributeArray');
+        $method->setAccessible(true);
+        $method->invoke($this, []);
     }
 
     /**
-     * @dataProvider innerHtmlProvider().
+     * @test
+     * @testdox getInnerHtmlOfMatchedElements() should retrieve the inner HTML
+     * @dataProvider provideInnerHtml
      */
-    public function testGetInnerHtmlOfMatchedElements($markup, $selector, $expected) {
-        $method = new ReflectionMethod($this->testcase, 'getInnerHtmlOfMatchedElements');
+    public function getInnerHtmlOfMatchedElements_should_retrieve_the_inner_HTML($markup, $selector, $expected) {
+        $method = new \ReflectionMethod($this, 'getInnerHtmlOfMatchedElements');
         $method->setAccessible(true);
 
-        $this->assertEquals($expected, $method->invoke($this->testcase, $markup, $selector));
+        $this->assertEquals($expected, $method->invoke($this, $markup, $selector));
     }
 
     /**
      * Data provider for testFlattenAttributeArray().
      */
-    public function attributeProvider()
+    public function provideAttributes()
     {
         return [
             'Single attribute' => [
@@ -238,7 +288,7 @@ public function attributeProvider()
     /**
      * Data provider for testGetInnerHtmlOfMatchedElements().
      */
-    public function innerHtmlProvider()
+    public function provideInnerHtml()
     {
         return [
             'A single match' => [
@@ -262,7 +312,7 @@ public function innerHtmlProvider()
     /**
      * Data provider for testAssertContainsSelector().
      */
-    public function selectorVariantProvider()
+    public function provideSelectorVariants()
     {
         return [
             'Simple tag name' => ['a'],
diff --git a/tests/TestFiles/TestCaseWithMarkupAssertions.php b/tests/TestFiles/TestCaseWithMarkupAssertions.php
deleted file mode 100644
index b794515..0000000
--- a/tests/TestFiles/TestCaseWithMarkupAssertions.php
+++ /dev/null
@@ -1,11 +0,0 @@
-<?php
-
-namespace Tests\TestFiles;
-
-use PHPUnit\Framework\TestCase;
-use SteveGrunwell\PHPUnit_Markup_Assertions\MarkupAssertionsTrait;
-
-class TestCaseWithMarkupAssertions extends TestCase
-{
-    use MarkupAssertionsTrait;
-}