diff --git a/apps/dav/tests/unit/Command/ListCalendarsTest.php b/apps/dav/tests/unit/Command/ListCalendarsTest.php
index b63a973668ef3f71b4fd23209bc57259e164fc41..c7dae373c94825e0adad0a443cad80aae602c8e2 100644
--- a/apps/dav/tests/unit/Command/ListCalendarsTest.php
+++ b/apps/dav/tests/unit/Command/ListCalendarsTest.php
@@ -63,7 +63,6 @@ class ListCalendarsTest extends TestCase {
 		);
 	}
 
-	
 	public function testWithBadUser() {
 		$this->expectException(\InvalidArgumentException::class);
 
@@ -76,7 +75,7 @@ class ListCalendarsTest extends TestCase {
 		$commandTester->execute([
 			'uid' => self::USERNAME,
 		]);
-		$this->assertContains("User <" . self::USERNAME . "> in unknown", $commandTester->getDisplay());
+		$this->assertStringContainsString("User <" . self::USERNAME . "> in unknown", $commandTester->getDisplay());
 	}
 
 	public function testWithCorrectUserWithNoCalendars() {
@@ -94,7 +93,7 @@ class ListCalendarsTest extends TestCase {
 		$commandTester->execute([
 			'uid' => self::USERNAME,
 		]);
-		$this->assertContains("User <" . self::USERNAME . "> has no calendars\n", $commandTester->getDisplay());
+		$this->assertStringContainsString("User <" . self::USERNAME . "> has no calendars\n", $commandTester->getDisplay());
 	}
 
 	public function dataExecute() {
@@ -133,7 +132,7 @@ class ListCalendarsTest extends TestCase {
 		$commandTester->execute([
 			'uid' => self::USERNAME,
 		]);
-		$this->assertContains($output, $commandTester->getDisplay());
-		$this->assertNotContains(BirthdayService::BIRTHDAY_CALENDAR_URI, $commandTester->getDisplay());
+		$this->assertStringContainsString($output, $commandTester->getDisplay());
+		$this->assertStringNotContainsString(BirthdayService::BIRTHDAY_CALENDAR_URI, $commandTester->getDisplay());
 	}
 }
diff --git a/apps/dav/tests/unit/Command/MoveCalendarTest.php b/apps/dav/tests/unit/Command/MoveCalendarTest.php
index a05674017277aa4b21fe33fa814a23b2ae7d6347..750863175a2d6c8274900438aaa104f265d3b1f7 100644
--- a/apps/dav/tests/unit/Command/MoveCalendarTest.php
+++ b/apps/dav/tests/unit/Command/MoveCalendarTest.php
@@ -121,7 +121,7 @@ class MoveCalendarTest extends TestCase {
 		]);
 	}
 
-	
+
 	public function testMoveWithInexistantCalendar() {
 		$this->expectException(\InvalidArgumentException::class);
 		$this->expectExceptionMessage('User <user> has no calendar named <personal>. You can run occ dav:list-calendars to list calendars URIs for this user.');
@@ -148,7 +148,7 @@ class MoveCalendarTest extends TestCase {
 		]);
 	}
 
-	
+
 	public function testMoveWithExistingDestinationCalendar() {
 		$this->expectException(\InvalidArgumentException::class);
 		$this->expectExceptionMessage('User <user2> already has a calendar named <personal>.');
@@ -313,7 +313,7 @@ class MoveCalendarTest extends TestCase {
 			'destinationuid' => 'user2',
 		]);
 
-		$this->assertContains("[OK] Calendar <personal> was moved from user <user> to <user2>", $commandTester->getDisplay());
+		$this->assertStringContainsString("[OK] Calendar <personal> was moved from user <user> to <user2>", $commandTester->getDisplay());
 	}
 
 	public function testMoveWithDestinationNotPartOfGroupAndForce() {
@@ -360,7 +360,7 @@ class MoveCalendarTest extends TestCase {
 			'--force' => true
 		]);
 
-		$this->assertContains("[OK] Calendar <personal> was moved from user <user> to <user2>", $commandTester->getDisplay());
+		$this->assertStringContainsString("[OK] Calendar <personal> was moved from user <user> to <user2>", $commandTester->getDisplay());
 	}
 
 	public function dataTestMoveWithCalendarAlreadySharedToDestination(): array {
diff --git a/tests/Core/Command/TwoFactorAuth/CleanupTest.php b/tests/Core/Command/TwoFactorAuth/CleanupTest.php
index 98425aee2231226669eec094223a11dd23429a75..75e869ad06f7cff0355920a5ab58e8286b2fcf8d 100644
--- a/tests/Core/Command/TwoFactorAuth/CleanupTest.php
+++ b/tests/Core/Command/TwoFactorAuth/CleanupTest.php
@@ -60,6 +60,6 @@ class CleanupTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$output = $this->cmd->getDisplay();
-		$this->assertContains("All user-provider associations for provider u2f have been removed", $output);
+		$this->assertStringContainsString("All user-provider associations for provider u2f have been removed", $output);
 	}
 }
diff --git a/tests/Core/Command/TwoFactorAuth/DisableTest.php b/tests/Core/Command/TwoFactorAuth/DisableTest.php
index fc0def50b90f4c9e3f539d51cf105212b2dd5a0b..5accaccb907e8d0081106581f954f54bc7ea0ee4 100644
--- a/tests/Core/Command/TwoFactorAuth/DisableTest.php
+++ b/tests/Core/Command/TwoFactorAuth/DisableTest.php
@@ -67,7 +67,7 @@ class DisableTest extends TestCase {
 		]);
 
 		$this->assertEquals(1, $rc);
-		$this->assertContains("Invalid UID", $this->command->getDisplay());
+		$this->assertStringContainsString("Invalid UID", $this->command->getDisplay());
 	}
 
 	public function testEnableNotSupported() {
@@ -87,7 +87,7 @@ class DisableTest extends TestCase {
 		]);
 
 		$this->assertEquals(2, $rc);
-		$this->assertContains("The provider does not support this operation", $this->command->getDisplay());
+		$this->assertStringContainsString("The provider does not support this operation", $this->command->getDisplay());
 	}
 
 	public function testEnabled() {
@@ -107,6 +107,6 @@ class DisableTest extends TestCase {
 		]);
 
 		$this->assertEquals(0, $rc);
-		$this->assertContains("Two-factor provider totp disabled for user ricky", $this->command->getDisplay());
+		$this->assertStringContainsString("Two-factor provider totp disabled for user ricky", $this->command->getDisplay());
 	}
 }
diff --git a/tests/Core/Command/TwoFactorAuth/EnableTest.php b/tests/Core/Command/TwoFactorAuth/EnableTest.php
index f3b66912f43c646274a267fc90a256e1a869eca1..fc71cc32148add94af51148c52862f7067cb3aa5 100644
--- a/tests/Core/Command/TwoFactorAuth/EnableTest.php
+++ b/tests/Core/Command/TwoFactorAuth/EnableTest.php
@@ -67,7 +67,7 @@ class EnableTest extends TestCase {
 		]);
 
 		$this->assertEquals(1, $rc);
-		$this->assertContains("Invalid UID", $this->command->getDisplay());
+		$this->assertStringContainsString("Invalid UID", $this->command->getDisplay());
 	}
 
 	public function testEnableNotSupported() {
@@ -87,7 +87,7 @@ class EnableTest extends TestCase {
 		]);
 
 		$this->assertEquals(2, $rc);
-		$this->assertContains("The provider does not support this operation", $this->command->getDisplay());
+		$this->assertStringContainsString("The provider does not support this operation", $this->command->getDisplay());
 	}
 
 	public function testEnabled() {
@@ -107,6 +107,6 @@ class EnableTest extends TestCase {
 		]);
 
 		$this->assertEquals(0, $rc);
-		$this->assertContains("Two-factor provider totp enabled for user belle", $this->command->getDisplay());
+		$this->assertStringContainsString("Two-factor provider totp enabled for user belle", $this->command->getDisplay());
 	}
 }
diff --git a/tests/Core/Command/TwoFactorAuth/EnforceTest.php b/tests/Core/Command/TwoFactorAuth/EnforceTest.php
index 48c09f7e63990884be6db1128c083c8973f11ed5..ed3deaa3fb341600ff9c85f1de4a044a81a317b9 100644
--- a/tests/Core/Command/TwoFactorAuth/EnforceTest.php
+++ b/tests/Core/Command/TwoFactorAuth/EnforceTest.php
@@ -64,7 +64,7 @@ class EnforceTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$display = $this->command->getDisplay();
-		$this->assertContains("Two-factor authentication is enforced for all users", $display);
+		$this->assertStringContainsString("Two-factor authentication is enforced for all users", $display);
 	}
 
 	public function testEnforceForOneGroup() {
@@ -82,7 +82,7 @@ class EnforceTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$display = $this->command->getDisplay();
-		$this->assertContains("Two-factor authentication is enforced for members of the group(s) twofactorers", $display);
+		$this->assertStringContainsString("Two-factor authentication is enforced for members of the group(s) twofactorers", $display);
 	}
 
 	public function testEnforceForAllExceptOneGroup() {
@@ -100,7 +100,7 @@ class EnforceTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$display = $this->command->getDisplay();
-		$this->assertContains("Two-factor authentication is enforced for all users, except members of yoloers", $display);
+		$this->assertStringContainsString("Two-factor authentication is enforced for all users, except members of yoloers", $display);
 	}
 
 	public function testDisableEnforced() {
@@ -117,7 +117,7 @@ class EnforceTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$display = $this->command->getDisplay();
-		$this->assertContains("Two-factor authentication is not enforced", $display);
+		$this->assertStringContainsString("Two-factor authentication is not enforced", $display);
 	}
 
 	public function testCurrentStateEnabled() {
@@ -129,7 +129,7 @@ class EnforceTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$display = $this->command->getDisplay();
-		$this->assertContains("Two-factor authentication is enforced for all users", $display);
+		$this->assertStringContainsString("Two-factor authentication is enforced for all users", $display);
 	}
 
 	public function testCurrentStateDisabled() {
@@ -141,6 +141,6 @@ class EnforceTest extends TestCase {
 
 		$this->assertEquals(0, $rc);
 		$display = $this->command->getDisplay();
-		$this->assertContains("Two-factor authentication is not enforced", $display);
+		$this->assertStringContainsString("Two-factor authentication is not enforced", $display);
 	}
 }
diff --git a/tests/Core/Command/TwoFactorAuth/StateTest.php b/tests/Core/Command/TwoFactorAuth/StateTest.php
index ce52bcf2751fe154b3414e71528c08d00a94f748..54ab85b51b80eaa394b53529b3df93ca2f9fd12f 100644
--- a/tests/Core/Command/TwoFactorAuth/StateTest.php
+++ b/tests/Core/Command/TwoFactorAuth/StateTest.php
@@ -61,7 +61,7 @@ class StateTest extends TestCase {
 		]);
 
 		$output = $this->cmd->getDisplay();
-		$this->assertContains("Invalid UID", $output);
+		$this->assertStringContainsString("Invalid UID", $output);
 	}
 
 	public function testStateNoProvidersActive() {
@@ -84,7 +84,7 @@ class StateTest extends TestCase {
 		]);
 
 		$output = $this->cmd->getDisplay();
-		$this->assertContains("Two-factor authentication is not enabled for user eldora", $output);
+		$this->assertStringContainsString("Two-factor authentication is not enabled for user eldora", $output);
 	}
 
 	public function testStateOneProviderActive() {
@@ -107,6 +107,6 @@ class StateTest extends TestCase {
 		]);
 
 		$output = $this->cmd->getDisplay();
-		$this->assertContains("Two-factor authentication is enabled for user mohamed", $output);
+		$this->assertStringContainsString("Two-factor authentication is enabled for user mohamed", $output);
 	}
 }
diff --git a/tests/lib/AppFramework/Http/DownloadResponseTest.php b/tests/lib/AppFramework/Http/DownloadResponseTest.php
index 1ad53f5db1348da92e1a11764e7fb1e2145ce3b6..6c509b8bc59f9a227b354bdb7c65e76b4f0e8654 100644
--- a/tests/lib/AppFramework/Http/DownloadResponseTest.php
+++ b/tests/lib/AppFramework/Http/DownloadResponseTest.php
@@ -45,7 +45,7 @@ class DownloadResponseTest extends \Test\TestCase {
 	public function testHeaders() {
 		$headers = $this->response->getHeaders();
 
-		$this->assertContains('attachment; filename="file"', $headers['Content-Disposition']);
-		$this->assertContains('content', $headers['Content-Type']);
+		$this->assertStringContainsString('attachment; filename="file"', $headers['Content-Disposition']);
+		$this->assertStringContainsString('content', $headers['Content-Type']);
 	}
 }