diff --git a/tests/Phug/Adapter/FileAdapterTest.php b/tests/Phug/Adapter/FileAdapterTest.php
index e4746127..6d3ac032 100644
--- a/tests/Phug/Adapter/FileAdapterTest.php
+++ b/tests/Phug/Adapter/FileAdapterTest.php
@@ -539,7 +539,7 @@ public function testCacheErrorTrace()
             'count' => 0,
         ]);
 
-        self::assertContains('on line 5, offset 6', $lastError);
+        self::assertStringContainsString('on line 5, offset 6', $lastError);
     }
 
     /**
@@ -673,7 +673,7 @@ public function testCacheDirectory()
         self::assertSame(2, $errErrors);
         self::assertStringEndsWith('errored', $errErrorDetails[0]['directory']);
         self::assertStringEndsWith('errored.pug', $errErrorDetails[0]['inputFile']);
-        self::assertContains(
+        self::assertStringContainsString(
             'Inconsistent indentation. Expecting either 0 or 4 spaces/tabs.',
             $errErrorDetails[0]['error']->getMessage()
         );
diff --git a/tests/Phug/CompilerModuleTest.php b/tests/Phug/CompilerModuleTest.php
index 8a1d395f..ed574bd0 100644
--- a/tests/Phug/CompilerModuleTest.php
+++ b/tests/Phug/CompilerModuleTest.php
@@ -49,7 +49,7 @@ public function testCompileEvent()
             $message = $exception->getMessage();
         }
 
-        self::assertContains('foo-bar.pug', $message);
+        self::assertStringContainsString('foo-bar.pug', $message);
     }
 
     /**
diff --git a/tests/Phug/OptimizerTest.php b/tests/Phug/OptimizerTest.php
index 1dfa4e01..5754027a 100644
--- a/tests/Phug/OptimizerTest.php
+++ b/tests/Phug/OptimizerTest.php
@@ -220,8 +220,8 @@ public function testCache()
             $contents .= file_get_contents($file);
         }
 
-        self::assertContains('<p>A</p>', $contents);
-        self::assertContains('<p>B</p>', $contents);
+        self::assertStringContainsString('<p>A</p>', $contents);
+        self::assertStringContainsString('<p>B</p>', $contents);
 
         $this->removeFile($cache);
     }
diff --git a/tests/Phug/Parser/TokenHandler/ExpansionTokenHandlerTest.php b/tests/Phug/Parser/TokenHandler/ExpansionTokenHandlerTest.php
index 942e3124..a7a5fa26 100644
--- a/tests/Phug/Parser/TokenHandler/ExpansionTokenHandlerTest.php
+++ b/tests/Phug/Parser/TokenHandler/ExpansionTokenHandlerTest.php
@@ -101,7 +101,7 @@ public function testHandleTokenElementException()
             $message = $exp->getMessage();
         }
 
-        self::assertContains('Expansion needs an element to work on', $message);
-        self::assertContains('Path: my-path', $message);
+        self::assertStringContainsString('Expansion needs an element to work on', $message);
+        self::assertStringContainsString('Path: my-path', $message);
     }
 }
diff --git a/tests/Phug/ProfilerModuleTest.php b/tests/Phug/ProfilerModuleTest.php
index 315ac94f..1f3473ae 100644
--- a/tests/Phug/ProfilerModuleTest.php
+++ b/tests/Phug/ProfilerModuleTest.php
@@ -55,15 +55,15 @@ public function testRenderProfiler()
         $render = $renderer->render('div');
 
         self::assertRegExp('/div lexing\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div lexing:', $render);
+        self::assertStringContainsString('title="div lexing:', $render);
         self::assertRegExp('/div parsing\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div parsing:', $render);
+        self::assertStringContainsString('title="div parsing:', $render);
         self::assertRegExp('/div compiling\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div compiling:', $render);
+        self::assertStringContainsString('title="div compiling:', $render);
         self::assertRegExp('/div formatting\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div formatting:', $render);
+        self::assertStringContainsString('title="div formatting:', $render);
         self::assertRegExp('/div rendering\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div rendering:', $render);
+        self::assertStringContainsString('title="div rendering:', $render);
 
         $renderer = new Renderer([
             'enable_profiler' => true,
@@ -118,15 +118,15 @@ public function testLogProfiler()
         $profiler->recordDisplayEvent(1);
         self::assertCount($count, $profiler->getEvents());
         self::assertRegExp('/div lexing\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div lexing:', $render);
+        self::assertStringContainsString('title="div lexing:', $render);
         self::assertRegExp('/div parsing\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div parsing:', $render);
+        self::assertStringContainsString('title="div parsing:', $render);
         self::assertRegExp('/div compiling\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div compiling:', $render);
+        self::assertStringContainsString('title="div compiling:', $render);
         self::assertRegExp('/div formatting\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div formatting:', $render);
+        self::assertStringContainsString('title="div formatting:', $render);
         self::assertRegExp('/div rendering\s*<br>\s*[\.\d]+[µm]?s/', $render);
-        self::assertContains('title="div rendering:', $render);
+        self::assertStringContainsString('title="div rendering:', $render);
     }
 
     /**
@@ -217,7 +217,7 @@ public function testExecutionMaxTime()
             $message = $exception->getMessage();
         }
 
-        self::assertContains('execution_max_time of 3ms exceeded.', $message);
+        self::assertStringContainsString('execution_max_time of 3ms exceeded.', $message);
     }
 
     /**
@@ -267,7 +267,7 @@ public function testMemoryLimit()
 
         unset($GLOBALS['LAkjdJHSmlakSJHGdjAJGdjGAHgsjHDAD']);
 
-        self::assertContains('memory_limit of '.$limit.'B exceeded.', $message);
+        self::assertStringContainsString('memory_limit of '.$limit.'B exceeded.', $message);
     }
 
     /**
@@ -288,16 +288,16 @@ public function testTokenDump()
         ]);
         $render = $renderer->render("a(href='a')\n  | Hello\ndiv");
 
-        self::assertContains('↩', $render);
-        self::assertContains('new line', $render);
-        self::assertContains('→', $render);
-        self::assertContains('indent', $render);
-        self::assertContains('←', $render);
-        self::assertContains('outdent', $render);
-        self::assertContains('(', $render);
-        self::assertContains('attributes start', $render);
-        self::assertContains(')', $render);
-        self::assertContains('attributes end', $render);
+        self::assertStringContainsString('↩', $render);
+        self::assertStringContainsString('new line', $render);
+        self::assertStringContainsString('→', $render);
+        self::assertStringContainsString('indent', $render);
+        self::assertStringContainsString('←', $render);
+        self::assertStringContainsString('outdent', $render);
+        self::assertStringContainsString('(', $render);
+        self::assertStringContainsString('attributes start', $render);
+        self::assertStringContainsString(')', $render);
+        self::assertStringContainsString('attributes end', $render);
     }
 
     /**
@@ -342,16 +342,16 @@ public function testDisplayProfiler()
         ob_end_clean();
 
         self::assertRegExp('/div lexing\s*<br>\s*[\.\d]+[µm]?s/', $contents);
-        self::assertContains('title="div lexing:', $contents);
+        self::assertStringContainsString('title="div lexing:', $contents);
         self::assertRegExp('/div parsing\s*<br>\s*[\.\d]+[µm]?s/', $contents);
-        self::assertContains('title="div parsing:', $contents);
+        self::assertStringContainsString('title="div parsing:', $contents);
         self::assertRegExp('/div compiling\s*<br>\s*[\.\d]+[µm]?s/', $contents);
-        self::assertContains('title="div compiling:', $contents);
+        self::assertStringContainsString('title="div compiling:', $contents);
         self::assertRegExp('/div formatting\s*<br>\s*[+-]?[\.\d]+[µm]?s/', $contents);
-        self::assertContains('title="div formatting:', $contents);
+        self::assertStringContainsString('title="div formatting:', $contents);
         self::assertRegExp('/div rendering\s*<br>\s*[\.\d]+[µm]?s/', $contents);
-        self::assertContains('title="div rendering:', $contents);
-        self::assertContains('-void-dump-', $contents);
+        self::assertStringContainsString('title="div rendering:', $contents);
+        self::assertStringContainsString('-void-dump-', $contents);
     }
 
     /**
@@ -401,7 +401,7 @@ public function testCustomDump()
 
         $render = $renderer->render('div');
 
-        self::assertContains('Phug\\Compiler\\Event\\NodeEvent', $render);
+        self::assertStringContainsString('Phug\\Compiler\\Event\\NodeEvent', $render);
     }
 
     /**
diff --git a/tests/Phug/RendererTest.php b/tests/Phug/RendererTest.php
index c26be0cf..d1743c0c 100644
--- a/tests/Phug/RendererTest.php
+++ b/tests/Phug/RendererTest.php
@@ -258,8 +258,8 @@ public function testBasedir()
         ]);
         $paths = $renderer->getCompiler()->getOption('paths');
         self::assertCount(2, $paths);
-        self::assertContains('a', $paths);
-        self::assertContains('b', $paths);
+        self::assertStringContainsString('a', $paths);
+        self::assertStringContainsString('b', $paths);
     }
 
     /**
@@ -478,12 +478,12 @@ public function testHandleErrorInString()
                 $message = $error->getMessage();
             }
 
-            self::assertContains(
+            self::assertStringContainsString(
                 'Division by zero',
                 $message
             );
 
-            self::assertNotContains(
+            self::assertStringNotContainsString(
                 'trigger_error("Division'.'by'.'zero")',
                 str_replace(' ', '', $message)
             );
@@ -497,12 +497,12 @@ public function testHandleErrorInString()
                 $message = $error->getMessage();
             }
 
-            self::assertContains(
+            self::assertStringContainsString(
                 'Division by zero on line 1',
                 $message
             );
 
-            self::assertContains(
+            self::assertStringContainsString(
                 'trigger_error("Division'.'by'.'zero")',
                 str_replace(' ', '', $message)
             );
@@ -516,12 +516,12 @@ public function testHandleErrorInString()
                 $message = $error->getMessage();
             }
 
-            self::assertContains(
+            self::assertStringContainsString(
                 'Division by zero on line 1',
                 $message
             );
 
-            self::assertContains(
+            self::assertStringContainsString(
                 "\033[43;30m>   1 | div: p\033[43;31m=\033[43;30mtrigger_error(\"Division by zero\")\e[0m\n",
                 $message
             );
@@ -575,18 +575,18 @@ public function testContextLines()
             $message = $error->getMessage();
         }
 
-        self::assertContains('Division by zero', $message);
-        self::assertContains('div: p=12/0', $message);
-        self::assertContains('// line -1', $message);
-        self::assertContains('// line +1', $message);
-        self::assertContains('// line -2', $message);
-        self::assertContains('// line +2', $message);
-        self::assertContains('// line -3', $message);
-        self::assertContains('// line +3', $message);
-        self::assertNotContains('// line -4', $message);
-        self::assertNotContains('// line +4', $message);
-        self::assertNotContains('// line -5', $message);
-        self::assertNotContains('// line +5', $message);
+        self::assertStringContainsString('Division by zero', $message);
+        self::assertStringContainsString('div: p=12/0', $message);
+        self::assertStringContainsString('// line -1', $message);
+        self::assertStringContainsString('// line +1', $message);
+        self::assertStringContainsString('// line -2', $message);
+        self::assertStringContainsString('// line +2', $message);
+        self::assertStringContainsString('// line -3', $message);
+        self::assertStringContainsString('// line +3', $message);
+        self::assertStringNotContainsString('// line -4', $message);
+        self::assertStringNotContainsString('// line +4', $message);
+        self::assertStringNotContainsString('// line -5', $message);
+        self::assertStringNotContainsString('// line +5', $message);
     }
 
     /**
@@ -624,17 +624,17 @@ public function testHandleErrorInFile()
         $renderer->renderFile($path);
         $message = str_replace('implode(): Invalid arguments passed', 'array, string given', $message ?: '');
 
-        self::assertContains(
+        self::assertStringContainsString(
             'array, string given',
             $message
         );
 
-        self::assertNotContains(
+        self::assertStringNotContainsString(
             'on line 3',
             $message
         );
 
-        self::assertNotContains(
+        self::assertStringNotContainsString(
             $path,
             $message
         );
@@ -644,17 +644,17 @@ public function testHandleErrorInFile()
         $renderer->renderFile($path);
         $message = str_replace('implode(): Invalid arguments passed', 'array, string given', $message ?: '');
 
-        self::assertContains(
+        self::assertStringContainsString(
             'array, string given on line 3, offset 2',
             $message
         );
 
-        self::assertContains(
+        self::assertStringContainsString(
             $path,
             $message
         );
 
-        self::assertContains(
+        self::assertStringContainsString(
             "implode('','')",
             $message
         );
@@ -814,8 +814,8 @@ public function testHandleHtmlError()
             /* @var RendererException $lastError */
             self::assertInstanceOf(RendererException::class, $lastError);
             $message = $lastError->getMessage();
-            self::assertContains('Division by zero on line 1, offset 7', $message);
-            self::assertContains('<span class="error-line">'.
+            self::assertStringContainsString('Division by zero on line 1, offset 7', $message);
+            self::assertStringContainsString('<span class="error-line">'.
                 'div: p=<span class="error-offset">1</span>2/0</span>', $message);
         }
     }
@@ -884,10 +884,10 @@ public function testHandleParseError()
             $message = $error->getMessage();
         }
 
-        self::assertContains('ParseError:', $message);
-        self::assertContains(' on line 12, offset 12', $message);
-        self::assertContains('title Foo', $message);
-        self::assertNotContains('Too far to be visible error context', $message);
+        self::assertStringContainsString('ParseError:', $message);
+        self::assertStringContainsString(' on line 12, offset 12', $message);
+        self::assertStringContainsString('title Foo', $message);
+        self::assertStringNotContainsString('Too far to be visible error context', $message);
     }
 
     public function testHeadIndent()
diff --git a/tests/Phug/Util/SandBoxTest.php b/tests/Phug/Util/SandBoxTest.php
index 5e5ab6fe..5cb780f0 100644
--- a/tests/Phug/Util/SandBoxTest.php
+++ b/tests/Phug/Util/SandBoxTest.php
@@ -62,7 +62,7 @@ public function testError()
         });
 
         self::assertInstanceOf(Exception::class, $sandBox->getThrowable());
-        self::assertContains('Division by zero', $sandBox->getThrowable()->getMessage());
+        self::assertStringContainsString('Division by zero', $sandBox->getThrowable()->getMessage());
         self::assertNull($sandBox->getResult());
         self::assertSame('foo', $sandBox->getBuffer());
 
@@ -77,7 +77,7 @@ public function testError()
         });
 
         self::assertInstanceOf(Exception::class, $sandBox->getThrowable());
-        self::assertContains('Notice', $sandBox->getThrowable()->getMessage());
+        self::assertStringContainsString('Notice', $sandBox->getThrowable()->getMessage());
 
         $level = error_reporting();