diff --git a/tests/src/Kernel/CsvExportTest.php b/tests/src/Kernel/CsvExportTest.php
index 61a2b0b..ab5f002 100644
--- a/tests/src/Kernel/CsvExportTest.php
+++ b/tests/src/Kernel/CsvExportTest.php
@@ -69,9 +69,9 @@ class CsvExportTest extends EntityKernelTestBase {
 
     $this->assertEquals($output, $streamed_output);
     // Tags stripped.
-    $this->assertContains(",angry", $streamed_output);
+    $this->assertStringContainsString(",angry", $streamed_output);
     // Whitespace trimmed.
-    $this->assertContains('"node 6",', $streamed_output);
+    $this->assertStringContainsString('"node 6",', $streamed_output);
   }
 
   /**
@@ -121,9 +121,9 @@ class CsvExportTest extends EntityKernelTestBase {
 
     $this->assertEquals($output, $streamed_output);
     // Tags not stripped.
-    $this->assertContains("<em>angry</em>", $streamed_output);
+    $this->assertStringContainsString("<em>angry</em>", $streamed_output);
     // Whitespace not trimmed.
-    $this->assertContains("\"\t node 6\",", $streamed_output);
+    $this->assertStringContainsString("\"\t node 6\",", $streamed_output);
   }
 
   /**
@@ -146,7 +146,7 @@ class CsvExportTest extends EntityKernelTestBase {
     $header = fgets($stream);
     $this->assertNotEmpty($header);
     // Pipe in the header should be replaced.
-    $this->assertContains('Some ; Codes', $header);
+    $this->assertStringContainsString('Some ; Codes', $header);
     $rows = [];
     while ($s = fgets($stream)) {
       $rows[] = $s;