diff --git a/.gitignore b/.gitignore
index fbbb6ee8..2b9ec0d2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,7 @@
+/.phpunit.cache/
 /node_modules/
 /vendor/
 /.phpcs.xml
-/.phpunit.result.cache
 /composer.lock
 /phpcs.xml
 /phpunit.xml
diff --git a/composer.json b/composer.json
index 83ccf301..2b776753 100644
--- a/composer.json
+++ b/composer.json
@@ -49,6 +49,14 @@
 		}
 	},
 	"scripts": {
+		"coverage": [
+			"@putenv WP_MULTISITE=1",
+			"@php ./vendor/bin/phpunit --exclude=ms-excluded --coverage-html ./.phpunit.cache/coverage-html"
+		],
+		"coverage-ci": [
+			"@putenv WP_MULTISITE=1",
+			"@php ./vendor/bin/phpunit --exclude=ms-excluded"
+		],
 		"cs": [
 			"@php ./vendor/bin/phpcs -p -s -v -n . --standard=\"WordPress-VIP-Go\" --extensions=php --ignore=\"/vendor/*,/node_modules/*,/tests/*\""
 		],
@@ -65,11 +73,11 @@
 			"bash bin/install-wp-tests.sh wordpress_test root root localhost"
 		],
 		"integration": [
-			"@php ./vendor/bin/phpunit --exclude=ms-required"
+			"@php ./vendor/bin/phpunit --exclude=ms-required --no-coverage"
 		],
 		"integration-ms": [
 			"@putenv WP_MULTISITE=1",
-			"@php ./vendor/bin/phpunit --exclude=ms-excluded"
+			"@php ./vendor/bin/phpunit --exclude=ms-excluded --no-coverage"
 		],
 		"behat": "run-behat-tests",
 		"behat-rerun": "rerun-behat-tests",
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 6a7a807a..7244c2b5 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,19 +1,42 @@
-<phpunit
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.6/phpunit.xsd"
-	bootstrap="tests/bootstrap.php"
-	backupGlobals="false"
-	colors="true"
-	beStrictAboutTestsThatDoNotTestAnything="true"
-	beStrictAboutOutputDuringTests="true"
-	convertErrorsToExceptions="true"
-	convertWarningsToExceptions="true"
-	convertNoticesToExceptions="true"
-	convertDeprecationsToExceptions="true"
->
-	<testsuites>
-		<testsuite name="default">
-			<directory prefix="test-" suffix=".php">./tests/</directory>
-		</testsuite>
-	</testsuites>
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.6/phpunit.xsd"
+         bootstrap="tests/Integration/bootstrap.php"
+         cacheResultFile=".phpunit.cache/test-results"
+         executionOrder="depends,defects"
+         forceCoversAnnotation="false"
+         beStrictAboutCoversAnnotation="false"
+         beStrictAboutOutputDuringTests="true"
+         beStrictAboutTodoAnnotatedTests="true"
+         convertDeprecationsToExceptions="true"
+         colors="true"
+         failOnRisky="true"
+         failOnWarning="true"
+		 testdox="true"
+         verbose="true">
+    <testsuites>
+        <testsuite name="Integration">
+            <directory>tests/Integration</directory>
+        </testsuite>
+    </testsuites>
+
+    <coverage cacheDirectory=".phpunit.cache/code-coverage"
+              processUncoveredFiles="true">
+        <include>
+			<file>co-authors-plus.php</file>
+			<file>template-tags.php</file>
+			<file>upgrade.php</file>
+			<directory>php</directory>
+        </include>
+		<exclude>
+			<!-- Inclusion of the next file breaks code coverage with Class "Yoast\WP\SEO\Generators\Schema\Author" not found -->
+			<file>php/integrations/yoast/class-coauthor.php</file>
+			<!-- The next view file has a floating $this which breaks PHPUnit coverage. -->
+			<file>php/integrations/amp/meta-author.php</file>
+		</exclude>
+		<report>
+			<text outputFile="php://stdout"/>
+			<clover outputFile=".phpunit.cache/clover.xml"/>
+		</report>
+    </coverage>
 </phpunit>
diff --git a/tests/test-author-queried-object.php b/tests/Integration/AuthorQueriedObjectTest.php
similarity index 96%
rename from tests/test-author-queried-object.php
rename to tests/Integration/AuthorQueriedObjectTest.php
index 2c0f8a26..77c68d2d 100644
--- a/tests/test-author-queried-object.php
+++ b/tests/Integration/AuthorQueriedObjectTest.php
@@ -3,7 +3,9 @@
  * Test Co-Authors Plus' modifications of author queries
  */
 
-class Test_Author_Queried_Object extends CoAuthorsPlus_TestCase {
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
+
+class AuthorQueriedObjectTest extends TestCase {
 
 	/**
 	 * On author pages, the queried object should only be set
diff --git a/tests/test-author-queries.php b/tests/Integration/AuthorQueriesTest.php
similarity index 94%
rename from tests/test-author-queries.php
rename to tests/Integration/AuthorQueriesTest.php
index ecb2f878..d8d7296a 100644
--- a/tests/test-author-queries.php
+++ b/tests/Integration/AuthorQueriesTest.php
@@ -1,6 +1,8 @@
 <?php
 
-class Test_Author_Queries extends CoAuthorsPlus_TestCase {
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
+
+class AuthorQueriesTest extends TestCase {
 
 	public function test__author_arg__user_is_post_author_query_as_post_author() {
 		$author_id = $this->factory()->user->create(
@@ -21,7 +23,7 @@ public function test__author_arg__user_is_post_author_query_as_post_author() {
 
 		wp_set_current_user( $author_id );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author' => $author_id,
 			)
@@ -48,7 +50,7 @@ public function test__author_arg__user_is_post_author() {
 		);
 		$this->_cap->add_coauthors( $post_id, array( $author->user_login ) );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author' => $author_id,
 			)
@@ -75,7 +77,7 @@ public function test__author_name_arg__user_is_post_author() {
 		);
 		$this->_cap->add_coauthors( $post_id, array( $author->user_login ) );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author_name' => $author->user_login,
 			)
@@ -110,7 +112,7 @@ public function test__author_name_arg__user_is_coauthor() {
 		);
 		$this->_cap->add_coauthors( $post_id, array( $author1->user_login, $author2->user_login ) );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author_name' => $author2->user_login,
 			)
@@ -145,7 +147,7 @@ public function test__author_arg__user_is_coauthor__author_arg() {
 		);
 		$this->_cap->add_coauthors( $post_id, array( $author1->user_login, $author2->user_login ) );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author' => $author2_id,
 			)
@@ -173,7 +175,7 @@ public function test__author_name_arg_plus_tax_query__user_is_post_author() {
 		$this->_cap->add_coauthors( $post_id, array( $author->user_login ) );
 		wp_set_post_terms( $post_id, 'test' );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author_name' => $author->user_login,
 				'tag'         => 'test',
@@ -210,7 +212,7 @@ public function tests__author_name_arg_plus_tax_query__is_coauthor() {
 		$this->_cap->add_coauthors( $post_id, array( $author1->user_login, $author2->user_login ) );
 		wp_set_post_terms( $post_id, 'test' );
 
-		$query = new WP_Query(
+		$query = new \WP_Query(
 			array(
 				'author_name' => $author2->user_login,
 				'tag'         => 'test',
diff --git a/tests/test-coauthors-plus.php b/tests/Integration/CoAuthorsPlusTest.php
similarity index 97%
rename from tests/test-coauthors-plus.php
rename to tests/Integration/CoAuthorsPlusTest.php
index cbe60ccb..90a2dfac 100644
--- a/tests/test-coauthors-plus.php
+++ b/tests/Integration/CoAuthorsPlusTest.php
@@ -1,6 +1,8 @@
 <?php
 
-class Test_CoAuthors_Plus extends CoAuthorsPlus_TestCase {
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
+
+class CoAuthorsPlusTest extends TestCase {
 
 	private $author1;
 	private $editor1;
@@ -72,7 +74,7 @@ public function test_get_coauthor_by_when_guest_author() {
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'id', $guest_author_id );
 
-		$this->assertInstanceOf( stdClass::class, $coauthor );
+		$this->assertInstanceOf( \stdClass::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor, 'ID' ) );
 		$this->assertEquals( $guest_author_id, $coauthor->ID );
 		$this->assertEquals( 'guest-author', $coauthor->type );
@@ -97,7 +99,7 @@ public function test_get_coauthor_by_when_guest_author_has_unicode_username() {
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'user_login', $user_login );
 
-		$this->assertInstanceOf( stdClass::class, $coauthor );
+		$this->assertInstanceOf( \stdClass::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor, 'ID' ) );
 		$this->assertEquals( $guest_author_id, $coauthor->ID );
 		$this->assertEquals( 'guest-author', $coauthor->type );
@@ -118,26 +120,26 @@ public function test_get_coauthor_by_when_guest_authors_not_enabled() {
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'id', $this->author1->ID );
 
-		$this->assertInstanceOf( WP_User::class, $coauthor );
+		$this->assertInstanceOf( \WP_User::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor, 'ID' ) );
 		$this->assertEquals( $this->author1->ID, $coauthor->ID );
 		$this->assertEquals( 'wpuser', $coauthor->type );
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'user_login', $this->author1->user_login );
 
-		$this->assertInstanceOf( WP_User::class, $coauthor );
+		$this->assertInstanceOf( \WP_User::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor->data, 'user_login' ) );
 		$this->assertEquals( $this->author1->user_login, $coauthor->user_login );
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'user_nicename', $this->author1->user_nicename );
 
-		$this->assertInstanceOf( WP_User::class, $coauthor );
+		$this->assertInstanceOf( \WP_User::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor->data, 'user_nicename' ) );
 		$this->assertEquals( $this->author1->user_nicename, $coauthor->user_nicename );
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'user_email', $this->author1->user_email );
 
-		$this->assertInstanceOf( WP_User::class, $coauthor );
+		$this->assertInstanceOf( \WP_User::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor->data, 'user_email' ) );
 		$this->assertEquals( $this->author1->user_email, $coauthor->user_email );
 
@@ -147,7 +149,7 @@ public function test_get_coauthor_by_when_guest_authors_not_enabled() {
 
 		$coauthor = $coauthors_plus->get_coauthor_by( 'id', $this->editor1->ID );
 
-		$this->assertInstanceOf( stdClass::class, $coauthor );
+		$this->assertInstanceOf( \stdClass::class, $coauthor );
 		$this->assertTrue( property_exists( $coauthor, 'linked_account' ) );
 		$this->assertEquals( $this->editor1->user_login, $coauthor->linked_account );
 	}
@@ -519,7 +521,7 @@ public function test_get_author_term_using_caching() {
 		$author_term        = $coauthors_plus->get_author_term( $this->author1 );
 		$author_term_cached = wp_cache_get( $cache_key, 'co-authors-plus' );
 
-		$this->assertInstanceOf( WP_Term::class, $author_term );
+		$this->assertInstanceOf( \WP_Term::class, $author_term );
 		$this->assertEquals( $author_term, $author_term_cached );
 	}
 
@@ -538,7 +540,7 @@ public function test_get_author_term_when_author_has_linked_account() {
 
 		$author_term = $coauthors_plus->get_author_term( $coauthor );
 
-		$this->assertInstanceOf( WP_Term::class, $author_term );
+		$this->assertInstanceOf( \WP_Term::class, $author_term );
 
 		// Checks when term does not exist or deleted somehow.
 		wp_delete_term( $author_term->term_id, $author_term->taxonomy );
@@ -566,7 +568,7 @@ public function test_get_author_term_when_author_has_not_linked_account() {
 
 		$author_term = $coauthors_plus->get_author_term( $coauthor );
 
-		$this->assertInstanceOf( WP_Term::class, $author_term );
+		$this->assertInstanceOf( \WP_Term::class, $author_term );
 
 		// Checks when term does not exist or deleted somehow.
 		wp_delete_term( $author_term->term_id, $author_term->taxonomy );
diff --git a/tests/test-coauthors-endpoint.php b/tests/Integration/EndpointsTest.php
similarity index 90%
rename from tests/test-coauthors-endpoint.php
rename to tests/Integration/EndpointsTest.php
index 1584627c..d412f9d4 100644
--- a/tests/test-coauthors-endpoint.php
+++ b/tests/Integration/EndpointsTest.php
@@ -1,11 +1,13 @@
 <?php
 
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
+
 use CoAuthors\API\Endpoints;
 
 /*
  * @coversDefaultClass \CoAuthors\API\Endpoints
  */
-class Test_Endpoints extends CoAuthorsPlus_TestCase {
+class EndpointsTest extends TestCase {
 
 	use \DMS\PHPUnitExtensions\ArraySubset\ArraySubsetAsserts;
 
@@ -91,8 +93,7 @@ public function set_up() {
 	}
 
 	/**
-	 * @covers ::__construct()
-	 * @covers ::modify_endpoints()
+	 * @covers \CoAuthors\API\Endpoints::__construct
 	 */
 	public function test_construct() {
 
@@ -121,7 +122,7 @@ public function test_construct() {
 	}
 
 	/**
-	 * @covers ::add_endpoints()
+	 * @covers \CoAuthors\API\Endpoints::add_endpoints
 	 */
 	public function test_add_endpoints() {
 
@@ -180,11 +181,11 @@ public function test_add_endpoints() {
 	}
 
 	/**
-	 * @covers ::get_coauthors_search_results()
+	 * @covers \CoAuthors\API\Endpoints::get_coauthors_search_results
 	 */
 	public function test_get_coauthors_search_results() {
 
-		$get_request = new WP_REST_Request( 'GET' );
+		$get_request = new \WP_REST_Request( 'GET' );
 		$get_request->set_url_params(
 			array(
 				'q'                => 'auth',
@@ -208,7 +209,7 @@ public function test_get_coauthors_search_results() {
 			'Failed to assert that coauthors search returns results matching the query.'
 		);
 
-		$not_found_get_request = new WP_REST_Request( 'GET' );
+		$not_found_get_request = new \WP_REST_Request( 'GET' );
 		$not_found_get_request->set_url_params(
 			array(
 				'q' => 'nonexistent',
@@ -224,7 +225,7 @@ public function test_get_coauthors_search_results() {
 	}
 
 	/**
-	 * @covers ::get_coauthors()
+	 * @covers \CoAuthors\API\Endpoints::get_coauthors
 	 */
 	public function test_authors_get_coauthors() {
 		$test_post = $this->factory()->post->create_and_get(
@@ -239,7 +240,7 @@ public function test_authors_get_coauthors() {
 
 		$test_post_id = $test_post->ID;
 
-		$get_request = new WP_REST_Request( 'GET' );
+		$get_request = new \WP_REST_Request( 'GET' );
 		$get_request->set_url_params(
 			array(
 				'post_id' => $test_post_id,
@@ -252,7 +253,7 @@ public function test_authors_get_coauthors() {
 	}
 
 	/**
-	 * @covers ::update_coauthors()
+	 * @covers \CoAuthors\API\Endpoints::update_coauthors
 	 */
 	public function test_update_coauthors() {
 
@@ -270,7 +271,7 @@ public function test_update_coauthors() {
 
 		$test_post_id = $test_post->ID;
 
-		$post_request = new WP_REST_Request( 'POST' );
+		$post_request = new \WP_REST_Request( 'POST' );
 		$post_request->set_url_params(
 			array(
 				'post_id'     => $test_post_id,
@@ -290,7 +291,7 @@ public function test_can_edit_coauthors() {
 			)
 		);
 
-		$request = new WP_REST_Request(
+		$request = new \WP_REST_Request(
 			'GET',
 			''
 		);
@@ -319,7 +320,7 @@ public function test_can_edit_coauthors__with_post_param() {
 			)
 		);
 
-		$request = new WP_REST_Request(
+		$request = new \WP_REST_Request(
 			'GET',
 			''
 		);
@@ -347,7 +348,7 @@ public function test_can_edit_coauthors__with_post_param() {
 	}
 
 	/**
-	 * @covers ::remove_author_link()
+	 * @covers \CoAuthors\API\Endpoints::remove_author_link
 	 */
 	public function test_remove_author_link() {
 
@@ -359,7 +360,7 @@ public function test_remove_author_link() {
 			)
 		);
 
-		$request = new WP_REST_Request( 'GET', '/wp/v2/posts/' . $test_post->ID );
+		$request = new \WP_REST_Request( 'GET', '/wp/v2/posts/' . $test_post->ID );
 
 		wp_set_current_user( $this->editor1->ID );
 
@@ -390,7 +391,7 @@ public function test_remove_author_link() {
 	}
 
 	/**
-	 * @covers ::modify_response()
+	 * @covers \CoAuthors\API\Endpoints::modify_responses
 	 */
 	public function test_modify_response() {
 		$this->_api->modify_responses();
diff --git a/tests/test-coauthors-guest-authors.php b/tests/Integration/GuestAuthorsTest.php
similarity index 96%
rename from tests/test-coauthors-guest-authors.php
rename to tests/Integration/GuestAuthorsTest.php
index e65627c3..84f2b218 100644
--- a/tests/test-coauthors-guest-authors.php
+++ b/tests/Integration/GuestAuthorsTest.php
@@ -1,8 +1,10 @@
 <?php
 
-class Test_CoAuthors_Guest_Authors extends CoAuthorsPlus_TestCase {
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
 
-	use Yoast\PHPUnitPolyfills\Polyfills\AssertStringContains;
+class GuestAuthorsTest extends TestCase {
+
+	use \Yoast\PHPUnitPolyfills\Polyfills\AssertStringContains;
 
 	private $admin1;
 	private $author1;
@@ -87,7 +89,7 @@ public function test_get_guest_author_by_using_cache() {
 		$guest_author        = $guest_author_obj->get_guest_author_by( 'ID', $guest_author_id );
 		$guest_author_cached = wp_cache_get( $cache_key, $guest_author_obj::$cache_group );
 
-		$this->assertInstanceOf( stdClass::class, $guest_author );
+		$this->assertInstanceOf( \stdClass::class, $guest_author );
 		$this->assertEquals( $guest_author, $guest_author_cached );
 	}
 
@@ -111,20 +113,20 @@ public function test_get_guest_author_by_with_different_keys() {
 		// Checks guest author using ID.
 		$guest_author = $guest_author_obj->get_guest_author_by( 'ID', $guest_author_id );
 
-		$this->assertInstanceOf( stdClass::class, $guest_author );
+		$this->assertInstanceOf( \stdClass::class, $guest_author );
 		$this->assertEquals( $guest_author_id, $guest_author->ID );
 		$this->assertEquals( $guest_author_obj->post_type, $guest_author->type );
 
 		// Checks guest author using user_nicename.
 		$guest_author = $guest_author_obj->get_guest_author_by( 'user_nicename', $this->editor1->user_nicename );
 
-		$this->assertInstanceOf( stdClass::class, $guest_author );
+		$this->assertInstanceOf( \stdClass::class, $guest_author );
 		$this->assertEquals( $guest_author_obj->post_type, $guest_author->type );
 
 		// Checks guest author using linked_account.
 		$guest_author = $guest_author_obj->get_guest_author_by( 'linked_account', $this->editor1->user_login );
 
-		$this->assertInstanceOf( stdClass::class, $guest_author );
+		$this->assertInstanceOf( \stdClass::class, $guest_author );
 		$this->assertEquals( $guest_author_obj->post_type, $guest_author->type );
 	}
 
@@ -305,7 +307,7 @@ public function test_create_guest_author_from_user_id() {
 		$guest_author_id = $guest_author_obj->create_guest_author_from_user_id( $this->editor1->ID );
 		$guest_author    = $guest_author_obj->get_guest_author_by( 'ID', $guest_author_id );
 
-		$this->assertInstanceOf( stdClass::class, $guest_author );
+		$this->assertInstanceOf( \stdClass::class, $guest_author );
 	}
 
 	/**
@@ -388,11 +390,11 @@ public function test_handle_delete_guest_author_action_with_nonce() {
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
-		$this->assertInstanceOf( 'WPDieException', $exception );
+		$this->assertInstanceOf( \WPDieException::class, $exception );
 		$this->assertStringContainsString( esc_html( $expected ), $exception->getMessage() );
 
 		// Checks when nonce is as expected.
@@ -400,7 +402,7 @@ public function test_handle_delete_guest_author_action_with_nonce() {
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
@@ -440,11 +442,11 @@ public function test_handle_delete_guest_author_action_with_list_users_capabilit
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
-		$this->assertInstanceOf( 'WPDieException', $exception );
+		$this->assertInstanceOf( \WPDieException::class, $exception );
 		$this->assertStringContainsString( esc_html( $expected ), $exception->getMessage() );
 
 		// Checks when current user has list_users capability.
@@ -455,7 +457,7 @@ public function test_handle_delete_guest_author_action_with_list_users_capabilit
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
@@ -497,11 +499,11 @@ public function test_handle_delete_guest_author_action_with_guest_author_existen
 		// Checks when guest author does not exist.
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
-		$this->assertInstanceOf( 'WPDieException', $exception );
+		$this->assertInstanceOf( \WPDieException::class, $exception );
 		$this->assertStringContainsString( esc_html( $expected ), $exception->getMessage() );
 
 		// Checks when guest author exists.
@@ -509,7 +511,7 @@ public function test_handle_delete_guest_author_action_with_guest_author_existen
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
@@ -552,11 +554,11 @@ public function test_handle_delete_guest_author_action_with_reassign_not_as_expe
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
-		$this->assertInstanceOf( 'WPDieException', $exception );
+		$this->assertInstanceOf( \WPDieException::class, $exception );
 		$this->assertStringContainsString( esc_html( $expected ), $exception->getMessage() );
 
 		// Restore current user from backup.
@@ -596,7 +598,7 @@ public function test_handle_delete_guest_author_action_with_reassign_is_leave_as
 
 			$guest_author_obj->handle_delete_guest_author_action();
 
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 
 			$this->assertStringContainsString( $guest_author_obj->parent_page, $e->getMessage() );
 			$this->assertStringContainsString( 'page=view-guest-authors', $e->getMessage() );
@@ -643,11 +645,11 @@ public function test_handle_delete_guest_author_action_with_reassign_is_reassign
 
 		try {
 			$guest_author_obj->handle_delete_guest_author_action();
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 			$exception = $e;
 		}
 
-		$this->assertInstanceOf( 'WPDieException', $exception );
+		$this->assertInstanceOf( \WPDieException::class, $exception );
 		$this->assertStringContainsString( esc_html( $expected ), $exception->getMessage() );
 
 		// When coauthor exists.
@@ -659,7 +661,7 @@ public function test_handle_delete_guest_author_action_with_reassign_is_reassign
 
 			$guest_author_obj->handle_delete_guest_author_action();
 
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 
 			//$this->assertStringContainsString( $guest_author_obj->parent_page, $e->getMessage() );
 			$this->assertStringContainsString( 'page=view-guest-authors', $e->getMessage() );
@@ -705,7 +707,7 @@ public function test_handle_delete_guest_author_action_with_reassign_is_remove_b
 
 			$guest_author_obj->handle_delete_guest_author_action();
 
-		} catch ( Exception $e ) {
+		} catch ( \Exception $e ) {
 
 			$this->assertStringContainsString( $guest_author_obj->parent_page, $e->getMessage() );
 			$this->assertStringContainsString( 'page=view-guest-authors', $e->getMessage() );
@@ -736,7 +738,7 @@ public function test_handle_delete_guest_author_action_with_reassign_is_remove_b
 	 **/
 	public function catch_redirect_destination( $location, $status ) {
 
-		throw new Exception( $location, $status );
+		throw new \Exception( $location, $status );
 	}
 
 	/**
diff --git a/tests/test-manage-coauthors.php b/tests/Integration/ManageCoAuthorsTest.php
similarity index 95%
rename from tests/test-manage-coauthors.php
rename to tests/Integration/ManageCoAuthorsTest.php
index 9781c19b..5c340814 100644
--- a/tests/test-manage-coauthors.php
+++ b/tests/Integration/ManageCoAuthorsTest.php
@@ -1,6 +1,8 @@
 <?php
 
-class Test_Manage_CoAuthors extends CoAuthorsPlus_TestCase {
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
+
+class ManageCoAuthorsTest extends TestCase {
 
 	private $admin1;
 	private $author1;
@@ -187,7 +189,7 @@ public function test_post_publish_count_for_coauthor() {
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_set_post_author_field()
+	 * @covers \CoAuthors_Plus::coauthors_set_post_author_field
 	 */
 	public function test_coauthors_set_post_author_field_when_post_type_is_attachment() {
 
@@ -229,7 +231,7 @@ public function test_coauthors_set_post_author_field_when_post_type_is_attachmen
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_set_post_author_field()
+	 * @covers \CoAuthors_Plus::coauthors_set_post_author_field
 	 */
 	public function test_coauthors_set_post_author_field_when_coauthor_is_not_set() {
 
@@ -253,7 +255,7 @@ public function test_coauthors_set_post_author_field_when_coauthor_is_not_set()
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_set_post_author_field()
+	 * @covers \CoAuthors_Plus::coauthors_set_post_author_field
 	 */
 	public function test_coauthors_set_post_author_field_when_coauthor_is_set() {
 
@@ -306,7 +308,7 @@ public function test_coauthors_set_post_author_field_when_coauthor_is_set() {
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_set_post_author_field()
+	 * @covers \CoAuthors_Plus::coauthors_set_post_author_field
 	 */
 	public function test_coauthors_set_post_author_field_when_guest_author_is_linked_with_wp_user() {
 
@@ -333,7 +335,7 @@ public function test_coauthors_set_post_author_field_when_guest_author_is_linked
 		);
 
 		// Create guest author with linked account with user.
-		$coauthors_plus->guest_authors = new CoAuthors_Guest_Authors();
+		$coauthors_plus->guest_authors = new \CoAuthors_Guest_Authors();
 		$coauthors_plus->guest_authors->create_guest_author_from_user_id( $this->author1 );
 
 		$new_data = $coauthors_plus->coauthors_set_post_author_field( $data, $post_array );
@@ -350,7 +352,7 @@ public function test_coauthors_set_post_author_field_when_guest_author_is_linked
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_set_post_author_field()
+	 * @covers \CoAuthors_Plus::coauthors_set_post_author_field
 	 */
 	public function test_coauthors_set_post_author_field_when_post_author_is_not_set() {
 
@@ -388,7 +390,7 @@ public function test_coauthors_set_post_author_field_when_post_author_is_not_set
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_update_post()
+	 * @covers \CoAuthors_Plus::coauthors_update_post
 	 */
 	public function test_coauthors_update_post_when_post_type_is_attachment() {
 
@@ -423,7 +425,7 @@ public function test_coauthors_update_post_when_post_type_is_attachment() {
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_update_post()
+	 * @covers \CoAuthors_Plus::coauthors_update_post
 	 */
 	public function test_coauthors_update_post_when_current_user_can_set_authors() {
 
@@ -469,7 +471,7 @@ public function test_coauthors_update_post_when_current_user_can_set_authors() {
 	 *
 	 * @see https://github.com/Automattic/Co-Authors-Plus/issues/198
 	 *
-	 * @covers ::coauthors_update_post()
+	 * @covers \CoAuthors_Plus::coauthors_update_post
 	 */
 	public function test_coauthors_update_post_when_post_has_not_author_terms() {
 
diff --git a/tests/test-template-tags.php b/tests/Integration/TemplateTagsTest.php
similarity index 99%
rename from tests/test-template-tags.php
rename to tests/Integration/TemplateTagsTest.php
index 28bed1b3..933abb9a 100644
--- a/tests/test-template-tags.php
+++ b/tests/Integration/TemplateTagsTest.php
@@ -1,8 +1,10 @@
 <?php
 
-class Test_Template_Tags extends CoAuthorsPlus_TestCase {
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
 
-	use Yoast\PHPUnitPolyfills\Polyfills\AssertStringContains;
+class TemplateTagsTest extends TestCase {
+
+	use \Yoast\PHPUnitPolyfills\Polyfills\AssertStringContains;
 
 	private $author1;
 	private $editor1;
@@ -17,7 +19,7 @@ public function set_up() {
 		 * we need CoAuthors_Template_Filters object to check 'the_author' filter.
 		 */
 		global $coauthors_plus_template_filters;
-		$coauthors_plus_template_filters = new CoAuthors_Template_Filters();
+		$coauthors_plus_template_filters = new \CoAuthors_Template_Filters();
 
 		$this->author1 = $this->factory()->user->create_and_get(
 			array(
diff --git a/tests/coauthorsplus-testcase.php b/tests/Integration/TestCase.php
similarity index 74%
rename from tests/coauthorsplus-testcase.php
rename to tests/Integration/TestCase.php
index 8b82d016..2834de18 100644
--- a/tests/coauthorsplus-testcase.php
+++ b/tests/Integration/TestCase.php
@@ -1,10 +1,13 @@
 <?php
+
+namespace Automattic\CoAuthorsPlus\Tests\Integration;
+
 use CoAuthors\API\Endpoints;
 
 /**
  * Base unit test class for Co-Authors Plus
  */
-class CoAuthorsPlus_TestCase extends \Yoast\WPTestUtils\WPIntegration\TestCase {
+class TestCase extends \Yoast\WPTestUtils\WPIntegration\TestCase {
 
 	/**
 	 * @var CoAuthors_Plus
diff --git a/tests/bootstrap.php b/tests/Integration/bootstrap.php
similarity index 88%
rename from tests/bootstrap.php
rename to tests/Integration/bootstrap.php
index 8bb30436..32aa881e 100644
--- a/tests/bootstrap.php
+++ b/tests/Integration/bootstrap.php
@@ -7,7 +7,7 @@
 
 use Yoast\WPTestUtils\WPIntegration;
 
-require_once dirname( __DIR__ ) . '/vendor/yoast/wp-test-utils/src/WPIntegration/bootstrap-functions.php';
+require_once dirname( dirname( __DIR__ ) ) . '/vendor/yoast/wp-test-utils/src/WPIntegration/bootstrap-functions.php';
 
 $_tests_dir = getenv( 'WP_TESTS_DIR' );
 
@@ -34,7 +34,7 @@
  */
 function _manually_load_plugin() {
 	// Updated from default (__FILE__), since this bootstrap is an extra level down in tests/Integration/.
-	require dirname( __DIR__ ) . '/co-authors-plus.php';
+	require dirname( dirname( __DIR__ ) ) . '/co-authors-plus.php';
 }
 
 tests_add_filter( 'muplugins_loaded', '_manually_load_plugin' );
@@ -54,4 +54,4 @@ function _manually_load_plugin() {
 WPIntegration\register_mockobject_autoloader();
 
 // Add custom test case.
-require __DIR__ . '/coauthorsplus-testcase.php';
+require __DIR__ . '/TestCase.php';
diff --git a/tests/fixtures/dummy-attachment.png b/tests/Integration/fixtures/dummy-attachment.png
similarity index 100%
rename from tests/fixtures/dummy-attachment.png
rename to tests/Integration/fixtures/dummy-attachment.png