diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..4b0cdb4
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,81 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test:
+    name: "PHPUnit: MW ${{ matrix.mw }}, PHP ${{ matrix.php }}"
+    continue-on-error: ${{ matrix.experimental }}
+
+    strategy:
+      matrix:
+        include:
+          - mw: 'REL1_39'
+            php: '8.1'
+            experimental: false
+          - mw: 'REL1_41'
+            php: '8.2'
+            experimental: false
+          - mw: 'REL1_42'
+            php: '8.3'
+            experimental: false
+          - mw: 'REL1_43'
+            php: '8.3'
+            experimental: false
+          - mw: 'master'
+            php: '8.4'
+            experimental: true
+
+    runs-on: ubuntu-latest
+
+
+    defaults:
+      run:
+        working-directory: mediawiki
+
+    steps:
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: mbstring, intl
+          tools: composer
+
+      - name: Cache MediaWiki
+        id: cache-mediawiki
+        uses: actions/cache@v3
+        with:
+          path: |
+            mediawiki
+            !mediawiki/extensions/
+            !mediawiki/vendor/
+          key: mw_${{ matrix.mw }}-php${{ matrix.php }}_v4
+
+      - name: Cache Composer cache
+        uses: actions/cache@v3
+        with:
+          path: ~/.composer/cache
+          key: composer-php${{ matrix.php }}
+
+      - uses: actions/checkout@v4
+        with:
+            path: EarlyCopy
+
+      - name: Install MediaWiki
+        if: steps.cache-mediawiki.outputs.cache-hit != 'true'
+        working-directory: ~
+        run: bash EarlyCopy/.github/workflows/installMediaWiki.sh ${{ matrix.mw }} WikibaseConstraintViolationsExport
+
+      - uses: actions/checkout@v4
+        with:
+          path: mediawiki/extensions/WikibaseConstraintViolationsExport
+
+      - run: composer update
+
+      - name: Run update.php
+        run: php maintenance/update.php --quick
+
+      - name: Run PHPUnit
+        run: php tests/phpunit/phpunit.php -c extensions/WikibaseConstraintViolationsExport/
diff --git a/.github/workflows/installMediaWiki.sh b/.github/workflows/installMediaWiki.sh
new file mode 100644
index 0000000..08e0803
--- /dev/null
+++ b/.github/workflows/installMediaWiki.sh
@@ -0,0 +1,54 @@
+#! /bin/bash
+
+MW_BRANCH=$1
+EXTENSION_NAME=$2
+
+wget "https://github.com/wikimedia/mediawiki/archive/refs/heads/$MW_BRANCH.tar.gz" -nv
+
+tar -zxf $MW_BRANCH.tar.gz
+mv mediawiki-$MW_BRANCH mediawiki
+
+cd mediawiki
+
+composer install
+php maintenance/install.php --dbtype sqlite --dbuser root --dbname mw --dbpath $(pwd) --pass AdminPassword WikiName AdminUser
+
+cat <<'EOT' >> LocalSettings.php
+error_reporting(E_ALL & ~E_DEPRECATED);
+ini_set("display_errors", "1");
+$wgShowExceptionDetails = true;
+$wgShowDBErrorBacktrace = true;
+$wgDevelopmentWarnings = true;
+EOT
+
+cat <<EOT >> LocalSettings.php
+wfLoadExtension( 'WikibaseRepository', __DIR__ . '/extensions/Wikibase/extension-repo.json' );
+require_once __DIR__ . '/extensions/Wikibase/repo/ExampleSettings.php';
+
+wfLoadExtension( 'WikibaseQualityConstraints' );
+wfLoadExtension( "$EXTENSION_NAME" );
+EOT
+
+cat <<EOT >> composer.local.json
+{
+	"extra": {
+		"merge-plugin": {
+			"merge-dev": true,
+			"include": [
+				"extensions/Wikibase/composer.json",
+				"extensions/$EXTENSION_NAME/composer.json"
+			]
+		}
+	}
+}
+EOT
+
+cd extensions
+git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/WikibaseQualityConstraints --depth=1  --branch=$MW_BRANCH --recurse-submodules -j8
+
+git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/Wikibase --depth=1 --branch=$MW_BRANCH -j8 && \
+  cd Wikibase && \
+  git submodule set-url view/lib/wikibase-serialization https://github.com/wmde/WikibaseSerializationJavaScript.git && \
+  git submodule set-url view/lib/wikibase-data-values https://github.com/wmde/DataValuesJavaScript.git && \
+  git submodule set-url view/lib/wikibase-data-model https://github.com/wmde/WikibaseDataModelJavaScript.git && \
+  git submodule sync && git submodule init && git submodule update --recursive
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..165765a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.phpunit.result.cache
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..65a2c15
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,11 @@
+.PHONY: ci test phpunit
+
+ci: test
+test: phpunit
+
+phpunit:
+ifdef filter
+	php ../../tests/phpunit/phpunit.php -c phpunit.xml.dist --filter $(filter)
+else
+	php ../../tests/phpunit/phpunit.php -c phpunit.xml.dist
+endif
diff --git a/maintenance/ExportConstraintViolations.php b/maintenance/ExportConstraintViolations.php
index 1878728..66e70df 100644
--- a/maintenance/ExportConstraintViolations.php
+++ b/maintenance/ExportConstraintViolations.php
@@ -4,16 +4,17 @@
 
 namespace ProfessionalWiki\WikibaseConstraintViolationsExport\Maintenance;
 
-use MediaWiki\Language\Language;
-use MediaWiki\Maintenance\Maintenance;
+use Language;
+use Maintenance;
 use MediaWiki\MediaWikiServices;
-use MediaWiki\Message\Message;
+use Message;
 use MessageLocalizer;
 use ProfessionalWiki\WikibaseConstraintViolationsExport\Presentation\PlainTextViolationMessageRenderer;
 use ValueFormatters\FormatterOptions;
 use ValueFormatters\ValueFormatter;
 use Wikibase\DataModel\Services\EntityId\EntityIdPager;
 use Wikibase\Lib\Formatters\SnakFormatter;
+use Wikibase\Repo\EntityIdLabelFormatterFactory;
 use Wikibase\Repo\Store\Sql\SqlEntityIdPagerFactory;
 use Wikibase\Repo\WikibaseRepo;
 use WikibaseQuality\ConstraintReport\ConstraintCheck\Result\CheckResult;
@@ -89,7 +90,7 @@ private function getViolationMessageRenderer(): PlainTextViolationMessageRendere
 		$language = MediaWikiServices::getInstance()->getLanguageFactory()->getLanguage( 'en' );
 
 		return new PlainTextViolationMessageRenderer(
-			entityIdFormatter: WikibaseRepo::getEntityIdLabelFormatterFactory()->getEntityIdFormatter( $language ),
+			entityIdFormatter: $this->getEntityIdLabelFormatter()->getEntityIdFormatter( $language ),
 			dataValueFormatter: $this->getValueFormatter( $language ),
 			languageNameUtils: MediaWikiServices::getInstance()->getLanguageNameUtils(),
 			userLanguageCode: $language->getCode(),
@@ -99,6 +100,14 @@ private function getViolationMessageRenderer(): PlainTextViolationMessageRendere
 		);
 	}
 
+	private function getEntityIdLabelFormatter(): EntityIdLabelFormatterFactory {
+		if ( method_exists( WikibaseRepo::class, 'getEntityIdLabelFormatterFactory' ) ) {
+			return WikibaseRepo::getEntityIdLabelFormatterFactory();
+		}
+
+		return new EntityIdLabelFormatterFactory();
+	}
+
 	private function getValueFormatter( Language $language ): ValueFormatter {
 		$formatterOptions = new FormatterOptions();
 		$formatterOptions->setOption( SnakFormatter::OPT_LANG, $language->getCode() );
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..e211081
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,12 @@
+<phpunit colors="true">
+	<testsuites>
+		<testsuite name="WikibaseConstraintViolationsExport">
+			<directory>tests/</directory>
+		</testsuite>
+	</testsuites>
+	<filter>
+		<whitelist addUncoveredFilesFromWhitelist="true">
+			<directory suffix=".php">src</directory>
+		</whitelist>
+	</filter>
+</phpunit>
diff --git a/src/Presentation/PlainTextViolationMessageRenderer.php b/src/Presentation/PlainTextViolationMessageRenderer.php
index bbcd89a..014f966 100644
--- a/src/Presentation/PlainTextViolationMessageRenderer.php
+++ b/src/Presentation/PlainTextViolationMessageRenderer.php
@@ -4,10 +4,11 @@
 
 namespace ProfessionalWiki\WikibaseConstraintViolationsExport\Presentation;
 
+use Config;
 use DataValues\DataValue;
-use MediaWiki\Config\Config;
+use InvalidArgumentException;
 use MediaWiki\Languages\LanguageNameUtils;
-use MediaWiki\Message\Message;
+use Message;
 use MessageLocalizer;
 use ValueFormatters\ValueFormatter;
 use Wikibase\DataModel\Entity\EntityId;
diff --git a/tests/Maintenance/ExportConstraintViolationsTest.php b/tests/Maintenance/ExportConstraintViolationsTest.php
new file mode 100644
index 0000000..83d674f
--- /dev/null
+++ b/tests/Maintenance/ExportConstraintViolationsTest.php
@@ -0,0 +1,173 @@
+<?php
+
+declare( strict_types = 1 );
+
+namespace ProfessionalWiki\WikibaseConstraintViolationsExport\Tests\Maintenance;
+
+use DataValues\StringValue;
+use MediaWiki\Tests\Maintenance\MaintenanceBaseTestCase;
+use ProfessionalWiki\WikibaseConstraintViolationsExport\Maintenance\ExportConstraintViolations;
+use Wikibase\DataModel\Entity\EntityDocument;
+use Wikibase\DataModel\Entity\Item;
+use Wikibase\DataModel\Entity\ItemId;
+use Wikibase\DataModel\Entity\NumericPropertyId;
+use Wikibase\DataModel\Entity\Property;
+use Wikibase\DataModel\Services\Statement\GuidGenerator;
+use Wikibase\DataModel\Snak\PropertyValueSnak;
+use Wikibase\DataModel\Statement\Statement;
+use Wikibase\DataModel\Term\Fingerprint;
+use Wikibase\DataModel\Term\Term;
+use Wikibase\DataModel\Term\TermList;
+use Wikibase\Repo\WikibaseRepo;
+use WikibaseQuality\ConstraintReport\Tests\DefaultConfig;
+
+/**
+ * @covers \ProfessionalWiki\WikibaseConstraintViolationsExport\Maintenance\ExportConstraintViolations
+ * @group Database
+ */
+class ExportConstraintViolationsTest extends MaintenanceBaseTestCase {
+
+	use DefaultConfig;
+
+	private const MULTI_VALUE_CONSTRAINT_ID = '1';
+	private const SINGLE_VALUE_CONSTRAINT_ID = '2';
+
+	private const MULTI_VALUE_CONSTRAINT_TYPE_ID = 'Q1';
+	private const SINGLE_VALUE_CONSTRAINT_TYPE_ID = 'Q2';
+
+	private const MULTI_VALUE_PROPERTY_ID = 'P1';
+	private const SINGLE_VALUE_PROPERTY_ID = 'P2';
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->overrideConfigValues( [
+			'WBQualityConstraintsMultiValueConstraintId' => self::MULTI_VALUE_CONSTRAINT_TYPE_ID,
+			'WBQualityConstraintsSingleValueConstraintId' => self::SINGLE_VALUE_CONSTRAINT_TYPE_ID
+		] );
+	}
+
+	protected function getMaintenanceClass(): string {
+		return ExportConstraintViolations::class;
+	}
+
+	public function addDBDataOnce() {
+		$this->saveProperty( self::MULTI_VALUE_PROPERTY_ID, 'string', 'Multiple Values' );
+		$this->saveProperty( self::SINGLE_VALUE_PROPERTY_ID, 'string', 'Single Value' );
+
+		$this->db->insert(
+			'wbqc_constraints',
+			[
+				[
+					'constraint_guid' => self::MULTI_VALUE_CONSTRAINT_ID,
+					'pid' => ( new NumericPropertyId( self::MULTI_VALUE_PROPERTY_ID ) )->getNumericId(),
+					'constraint_type_qid' => self::MULTI_VALUE_CONSTRAINT_TYPE_ID,
+					'constraint_parameters' => '{}',
+				],
+				[
+					'constraint_guid' => self::SINGLE_VALUE_CONSTRAINT_ID,
+					'pid' => ( new NumericPropertyId( self::SINGLE_VALUE_PROPERTY_ID ) )->getNumericId(),
+					'constraint_type_qid' => self::SINGLE_VALUE_CONSTRAINT_TYPE_ID,
+					'constraint_parameters' => '{}',
+				]
+			]
+		);
+	}
+
+	public function testExportsEmptyArrayIfThereAreNoViolations() : void{
+		$item1 = new Item( new ItemId( 'Q100' ) );
+		$this->addStatement( $item1, self::MULTI_VALUE_PROPERTY_ID, 'multi value 1' );
+		$this->addStatement( $item1, self::MULTI_VALUE_PROPERTY_ID, 'multi value 2' );
+		$this->addStatement( $item1, self::SINGLE_VALUE_PROPERTY_ID, 'single value 1' );
+
+		$this->maintenance->execute();
+
+		$this->expectOutputString( '[]' );
+	}
+
+	public function testExportsViolations() : void{
+		$item1 = new Item( new ItemId( 'Q100' ) );
+		$this->addStatement( $item1, self::MULTI_VALUE_PROPERTY_ID, 'multi value 1' );
+		$this->addStatement( $item1, self::SINGLE_VALUE_PROPERTY_ID, 'single value 1' );
+
+		$item2 = new Item( new ItemId( 'Q200' ) );
+		$this->addStatement( $item2, self::MULTI_VALUE_PROPERTY_ID, 'multi value 1' );
+		$this->addStatement( $item2, self::MULTI_VALUE_PROPERTY_ID, 'multi value 2' );
+		$this->addStatement( $item2, self::SINGLE_VALUE_PROPERTY_ID, 'single value 1' );
+		$this->addStatement( $item2, self::SINGLE_VALUE_PROPERTY_ID, 'single value 2' );
+
+		$this->maintenance->execute();
+
+		$this->assertEqualsCanonicalizing(
+			[
+				'Q100' => [
+					[
+						'status' => 'warning',
+						'propertyId' => self::MULTI_VALUE_PROPERTY_ID,
+						'messageKey' => 'wbqc-violation-message-multi-value',
+						'message' => 'This property should contain multiple values.',
+						'constraintId' => self::MULTI_VALUE_CONSTRAINT_ID,
+						'constraintType' => self::MULTI_VALUE_CONSTRAINT_TYPE_ID,
+						'value' => 'multi value 1'
+					]
+				],
+				'Q200' => [
+					[
+						'status' => 'warning',
+						'propertyId' => self::SINGLE_VALUE_PROPERTY_ID,
+						'messageKey' => 'wbqc-violation-message-single-value',
+						'message' => 'This property should only contain a single value.',
+						'constraintId' => self::SINGLE_VALUE_CONSTRAINT_ID,
+						'constraintType' => self::SINGLE_VALUE_CONSTRAINT_TYPE_ID,
+						'value' => 'single value 2'
+					],
+					[
+						'status' => 'warning',
+						'propertyId' => self::SINGLE_VALUE_PROPERTY_ID,
+						'messageKey' => 'wbqc-violation-message-single-value',
+						'message' => 'This property should only contain a single value.',
+						'constraintId' => self::SINGLE_VALUE_CONSTRAINT_ID,
+						'constraintType' => self::SINGLE_VALUE_CONSTRAINT_TYPE_ID,
+						'value' => 'single value 1'
+					]
+				]
+			],
+			json_decode( $this->getActualOutput(), true )
+		);
+	}
+
+	protected function saveEntity( EntityDocument $entity ): void {
+		WikibaseRepo::getEntityStore()->saveEntity(
+			entity: $entity,
+			summary: __CLASS__,
+			user: self::getTestSysop()->getUser()
+		);
+	}
+
+	protected function saveProperty( string $pId, string $type, string $label ): void {
+		$this->saveEntity(
+			new Property(
+				id: new NumericPropertyId( $pId ),
+				fingerprint: new Fingerprint( labels: new TermList( [
+					new Term( languageCode: 'en', text: $label )
+				] ) ),
+				dataTypeId: $type
+			)
+		);
+	}
+
+	protected function addStatement( EntityDocument $entity, string $propertyId, string $value ): void {
+		$statementGuidGenerator = new GuidGenerator();
+
+		$dataValue = new StringValue( $value );
+		$snak = new PropertyValueSnak( new NumericPropertyId( $propertyId ), $dataValue );
+		$statement = new Statement( $snak );
+		$statementGuid = $statementGuidGenerator->newGuid( $entity->getId() );
+		$statement->setGuid( $statementGuid );
+
+		$entity->getStatements()->addStatement( $statement );
+
+		$this->saveEntity( $entity );
+	}
+
+}