diff --git a/tests/phpunit.xml b/tests/phpunit.xml
index 3df457589..062b37156 100644
--- a/tests/phpunit.xml
+++ b/tests/phpunit.xml
@@ -1,24 +1,19 @@
-<?xml version="1.0" encoding="utf-8" ?>
+<?xml version="1.0" encoding="utf-8"?>
 <!--
   - SPDX-FileCopyrightText: 2017 Nextcloud GmbH and Nextcloud contributors
   - SPDX-License-Identifier: AGPL-3.0-or-later
 -->
-<phpunit bootstrap="bootstrap.php" convertDeprecationsToExceptions="true">
-	<testsuite name="circles">
-		<directory suffix='Test.php'>.</directory>
-	</testsuite>
-	<filter>
-		<whitelist>
-			<directory suffix=".php">../appinfo</directory>
-			<directory suffix=".php">../lib</directory>
-		</whitelist>
-	</filter>
-	<logging>
-		<log type="coverage-clover" target="clover.xml"/>
-		<!--<log type="coverage-text" target="php://stdout" showUncoveredFiles="false"/>-->
-	</logging>
-	<listeners>
-		<listener class="OCA\Circles\Tests\Env" file="TestSuiteListener.php"/>
-	</listeners>
-
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="bootstrap.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd" cacheDirectory=".phpunit.cache">
+  <testsuite name="circles">
+    <directory suffix="Test.php">.</directory>
+  </testsuite>
+  <logging>
+    <!--<log type="coverage-text" target="php://stdout" showUncoveredFiles="false"/>-->
+  </logging>
+  <source>
+    <include>
+      <directory suffix=".php">../appinfo</directory>
+      <directory suffix=".php">../lib</directory>
+    </include>
+  </source>
 </phpunit>
diff --git a/tests/unit/CirclesManagerTest.php b/tests/unit/CirclesManagerTest.php
new file mode 100644
index 000000000..c10c55721
--- /dev/null
+++ b/tests/unit/CirclesManagerTest.php
@@ -0,0 +1,162 @@
+<?php
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Circles\Tests;
+
+use OCA\Circles\CirclesManager;
+use OCA\Circles\Model\Circle;
+use OCA\Circles\Model\FederatedUser;
+use OCA\Circles\Model\Member;
+use OCA\Circles\Model\Probes\DataProbe;
+use OCP\IGroupManager;
+use OCP\IUserManager;
+use Test\TestCase;
+
+/**
+ * @group DB
+ */
+class CirclesManagerTest extends TestCase {
+	private CirclesManager $circlesManager;
+	private string $userId = 'circles-testuser';
+	private string $groupId = 'circles-testgroup';
+	private string $circleName;
+
+	public function setUp(): void {
+		parent::setUp();
+
+		// Random circle name
+		$this->circleName = sha1(uniqId(mt_rand(), true));
+
+		// Create test user
+		$userManager = \OC::$server->get(IUserManager::class);
+		if (!$userManager->userExists($this->userId)) {
+			$user = $userManager->createUser($this->userId, $this->userId);
+		} else {
+			$user = $userManager->get($this->userId);
+		}
+
+		// Create test group and add user
+		$groupManager = \OC::$server->get(IGroupManager::class);
+		if (!$groupManager->groupExists($this->groupId)) {
+			$group = $groupManager->createGroup($this->groupId);
+			$group->addUser($user);
+		}
+
+		$this->circlesManager = \OC::$server->get(CirclesManager::class);
+
+	}
+
+	// Start user session as user (default: test user)
+	private function startSession(?string $userId = null): FederatedUser {
+		if (!$userId) {
+			$userId = $this->userId;
+		}
+		$federatedUser = $this->circlesManager->getLocalFederatedUser($userId);
+		$this->circlesManager->startSession($federatedUser, true);
+		return $federatedUser;
+	}
+
+	public function testCreateCircle(): void {
+		$federatedUser = $this->startSession();
+
+		// Created circle has properties
+		$circle = $this->circlesManager->createCircle($this->circleName);
+		$this->assertEquals($this->circleName, $circle->getName());
+		$this->assertEquals($this->circleName, $circle->getDisplayName());
+		$this->assertEquals($this->circleName, $circle->getSanitizedName());
+		$this->assertEquals($federatedUser->getSingleId(), $circle->getOwner()->getSingleId());
+		$this->assertEquals($federatedUser->getSingleId(), $circle->getInitiator()->getSingleId());
+
+		// Created circle returned by probeCircle()
+		$circles = $this->circlesManager->probeCircles();
+		$this->assertCount(1, array_filter($circles, function (Circle $c) { return $c->getName() === $this->circleName; }));
+
+		// Destroyed circle not returned by probeCircle()
+		$this->circlesManager->destroyCircle($circle->getSingleId());
+		$circles = $this->circlesManager->probeCircles();
+		$this->assertCount(0, array_filter($circles, function (Circle $c) { return $c->getName() === $this->circleName; }));
+	}
+
+	public function testGetCirclesWithInitiator(): void {
+		// Create circle as user 'admin' and add test user as member
+		$this->startSession('admin');
+		$adminCircle = $this->circlesManager->createCircle($this->circleName);
+		$this->circlesManager->addMember($adminCircle->getSingleId(), $this->circlesManager->getLocalFederatedUser($this->userId));
+
+		// Get circles as test user
+		$federatedUser = $this->startSession();
+		$circles = $this->circlesManager->getCircles();
+		$circle = null;
+		foreach ($circles as $c) {
+			if ($c->getSingleId() === $adminCircle->getSingleId()) {
+				$circle = $c;
+			}
+		}
+
+		// Initiator of probed circle has correct properties
+		$this->assertEquals($federatedUser->getSingleId(), $circle->getInitiator()->getSingleId());
+		$this->assertEquals(1, $circle->getInitiator()->getLevel());
+
+		// Destroy circle as user 'admin'
+		$this->startSession('admin');
+		$this->circlesManager->destroyCircle($adminCircle->getSingleId());
+	}
+
+	public function testProbeCirclesWithInitiator(): void {
+		// Create circle as user 'admin' and add test user as member
+		$this->startSession('admin');
+		$adminCircle = $this->circlesManager->createCircle($this->circleName);
+		$this->circlesManager->addMember($adminCircle->getSingleId(), $this->circlesManager->getLocalFederatedUser($this->userId));
+
+		// Probe circles as test user
+		$federatedUser = $this->startSession();
+		$dataProbe = new DataProbe();
+		$dataProbe->add(DataProbe::INITIATOR);
+		$circles = $this->circlesManager->probeCircles(null, $dataProbe);
+		$circle = null;
+		foreach ($circles as $c) {
+			if ($c->getSingleId() === $adminCircle->getSingleId()) {
+				$circle = $c;
+			}
+		}
+
+		// Initiator of probed circle has correct properties
+		$this->assertEquals($federatedUser->getSingleId(), $circle->getInitiator()->getSingleId());
+		$this->assertEquals(1, $circle->getInitiator()->getLevel());
+
+		// Destroy circle as user 'admin'
+		$this->startSession('admin');
+		$this->circlesManager->destroyCircle($adminCircle->getSingleId());
+	}
+
+	public function testProbeCirclesWithInitiatorAsGroupMember(): void {
+		// Create circle as user 'admin' and add test group as member
+		$this->startSession('admin');
+		$adminCircle = $this->circlesManager->createCircle($this->circleName);
+		$federatedGroup = $this->circlesManager->getFederatedUser($this->groupId, Member::TYPE_GROUP);
+		$this->circlesManager->addMember($adminCircle->getSingleId(), $federatedGroup);
+
+		// Probe circles as test user
+		$federatedUser = $this->startSession();
+		$dataProbe = new DataProbe();
+		$dataProbe->add(DataProbe::INITIATOR);
+		$circles = $this->circlesManager->probeCircles(null, $dataProbe);
+		$circle = null;
+		foreach ($circles as $c) {
+			if ($c->getSingleId() === $adminCircle->getSingleId()) {
+				$circle = $c;
+			}
+		}
+
+		// Initiator of probed circle has correct properties
+		$this->assertEquals($federatedGroup->getSingleId(), $circle->getInitiator()->getSingleId());
+		$this->assertEquals(1, $circle->getInitiator()->getLevel());
+
+		// Destroy circle as user 'admin'
+		$this->startSession('admin');
+		$this->circlesManager->destroyCircle($adminCircle->getSingleId());
+	}
+}
diff --git a/tests/unit/lib/Controller/AdminControllerTest.php b/tests/unit/lib/Controller/AdminControllerTest.php
index 9a2cb007f..a992a6a22 100644
--- a/tests/unit/lib/Controller/AdminControllerTest.php
+++ b/tests/unit/lib/Controller/AdminControllerTest.php
@@ -108,7 +108,7 @@ public function testCirclesList(int $limit, int $offset): void {
 		$this->assertEquals($response, $this->adminController->circles('an-user-id', $limit, $offset));
 	}
 
-	public function dataForCirclesList(): array {
+	public static function dataForCirclesList(): array {
 		return [
 			[-1, 0],
 			[1, 1]
diff --git a/tests/unit/lib/Controller/LocalControllerTest.php b/tests/unit/lib/Controller/LocalControllerTest.php
index f28bff611..38966cff7 100644
--- a/tests/unit/lib/Controller/LocalControllerTest.php
+++ b/tests/unit/lib/Controller/LocalControllerTest.php
@@ -117,7 +117,7 @@ public function testCirclesList(int $limit, int $offset): void {
 		$this->assertEquals($response, $this->localController->circles($limit, $offset));
 	}
 
-	public function dataForCirclesList(): array {
+	public static function dataForCirclesList(): array {
 		return [
 			[-1, 0],
 			[1, 1]