diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index f2947bfff..8b16ef572 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -10,6 +10,41 @@ parameters:
 			count: 1
 			path: src/Collector/DefaultCollector.php
 
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsolePrinter\\:\\:printLine\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Console/ConsolePrinter.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsoleReporter\\:\\:printFooter\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Console/ConsoleReporter.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsoleReporter\\:\\:printLegend\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Console/ConsoleReporter.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsoleReporter\\:\\:report\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Console/ConsoleReporter.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsoleReporter\\:\\:reportWithCustomAndGlobalMaximumDuration\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Console/ConsoleReporter.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsoleReporter\\:\\:reportWithGlobalMaximumDuration\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Console/ConsoleReporter.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Reporter\\:\\:report\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: src/Reporter/Reporter.php
+
 		-
 			message: "#^Offset 'major' does not exist on array\\{0\\?\\: string, major\\?\\: numeric\\-string, 1\\?\\: numeric\\-string, 2\\?\\: '0'\\|\\(non\\-falsy\\-string&numeric\\-string\\), minor\\?\\: ''\\|numeric\\-string, 3\\?\\: ''\\|numeric\\-string, 4\\?\\: '0'\\|\\(non\\-falsy\\-string&numeric\\-string\\)\\}\\.$#"
 			count: 1
@@ -240,6 +275,11 @@ parameters:
 			count: 1
 			path: test/Unit/Exception/InvalidNanosecondsTest.php
 
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Exception\\\\InvalidOutputTest\\:\\:testNotResourceReturnsException\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: test/Unit/Exception/InvalidOutputTest.php
+
 		-
 			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Exception\\\\InvalidPhaseIdentifierTest\\:\\:testBlankOrEmptyReturnsException\\(\\) has no return type specified\\.$#"
 			count: 1
@@ -336,15 +376,50 @@ parameters:
 			path: test/Unit/Reporter/Console/ColorTest.php
 
 		-
-			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Reporter\\\\Console\\\\ConsoleReporterTest\\:\\:testReportReturnsEmptyStringWhenSlowTestListIsEmpty\\(\\) has no return type specified\\.$#"
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Reporter\\\\Console\\\\ConsolePrinterTest\\:\\:testPrintLineWritesLineFollowedByNewlineToResource\\(\\) has no return type specified\\.$#"
+			count: 1
+			path: test/Unit/Reporter/Console/ConsolePrinterTest.php
+
+		-
+			message: "#^Parameter \\#1 \\$fp of function rewind expects resource, resource\\|false given\\.$#"
+			count: 1
+			path: test/Unit/Reporter/Console/ConsolePrinterTest.php
+
+		-
+			message: "#^Parameter \\#1 \\$output of class Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsolePrinter constructor expects resource, resource\\|false given\\.$#"
+			count: 1
+			path: test/Unit/Reporter/Console/ConsolePrinterTest.php
+
+		-
+			message: "#^Parameter \\#1 \\$source of function stream_get_contents expects resource, resource\\|false given\\.$#"
+			count: 1
+			path: test/Unit/Reporter/Console/ConsolePrinterTest.php
+
+		-
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Reporter\\\\Console\\\\ConsoleReporterTest\\:\\:testReportPrintsNothingWhenSlowTestListIsEmpty\\(\\) has no return type specified\\.$#"
 			count: 1
 			path: test/Unit/Reporter/Console/ConsoleReporterTest.php
 
 		-
-			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Reporter\\\\Console\\\\ConsoleReporterTest\\:\\:testReportReturnsReportWhenSlowTestListHasFewerSlowTestsThanMaximumCount\\(\\) has no return type specified\\.$#"
+			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Reporter\\\\Console\\\\ConsoleReporterTest\\:\\:testReportPrintsReportWhenSlowTestListHasFewerSlowTestsThanMaximumCount\\(\\) has no return type specified\\.$#"
 			count: 1
 			path: test/Unit/Reporter/Console/ConsoleReporterTest.php
 
+		-
+			message: "#^Parameter \\#1 \\$fp of function rewind expects resource, resource\\|false given\\.$#"
+			count: 2
+			path: test/Unit/Reporter/Console/ConsoleReporterTest.php
+
+		-
+			message: "#^Parameter \\#1 \\$output of class Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Reporter\\\\Console\\\\ConsolePrinter constructor expects resource, resource\\|false given\\.$#"
+			count: 2
+			path: test/Unit/Reporter/Console/ConsoleReporterTest.php
+
+		-
+			message: "#^Parameter \\#1 \\$source of function stream_get_contents expects resource, resource\\|false given\\.$#"
+			count: 2
+			path: test/Unit/Reporter/Console/ConsoleReporterTest.php
+
 		-
 			message: "#^Method Ergebnis\\\\PHPUnit\\\\SlowTestDetector\\\\Test\\\\Unit\\\\Reporter\\\\Console\\\\DurationFormatterTest\\:\\:testFormatFormats\\(\\) has no return type specified\\.$#"
 			count: 1
diff --git a/src/Exception/InvalidOutput.php b/src/Exception/InvalidOutput.php
new file mode 100644
index 000000000..a5107b8bc
--- /dev/null
+++ b/src/Exception/InvalidOutput.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2021-2026 Andreas Möller
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE.md file that was distributed with this source code.
+ *
+ * @see https://github.com/ergebnis/phpunit-slow-test-detector
+ */
+
+namespace Ergebnis\PHPUnit\SlowTestDetector\Exception;
+
+/**
+ * @internal
+ */
+final class InvalidOutput extends \InvalidArgumentException
+{
+    /**
+     * @param mixed $output
+     */
+    public static function notResource($output): self
+    {
+        return new self(\sprintf(
+            'Output needs to be a resource, got %s instead.',
+            \is_object($output) ? \get_class($output) : \gettype($output)
+        ));
+    }
+}
diff --git a/src/Extension.php b/src/Extension.php
index fa370fd65..dbfbe62ea 100644
--- a/src/Extension.php
+++ b/src/Extension.php
@@ -68,6 +68,10 @@ public function __construct(array $options = [])
             $this->maximumDuration = $maximumDuration;
             $this->collector = new Collector\DefaultCollector();
             $this->reporter = new Reporter\Console\ConsoleReporter(
+                new Reporter\Console\ConsolePrinter(\fopen(
+                    'php://stdout',
+                    'wb'
+                )),
                 new Reporter\Console\DurationFormatter(),
                 $maximumDuration,
                 $maximumCount
@@ -135,13 +139,7 @@ public function endTestSuite(Framework\TestSuite $suite)
                 return;
             }
 
-            $report = $this->reporter->report($slowTestList);
-
-            if ('' === $report) {
-                return;
-            }
-
-            echo $report;
+            $this->reporter->report($slowTestList);
         }
 
         public function startTest(Framework\Test $test)
@@ -272,6 +270,10 @@ public function __construct(array $options = [])
             $this->maximumDuration = $maximumDuration;
             $this->collector = new Collector\DefaultCollector();
             $this->reporter = new Reporter\Console\ConsoleReporter(
+                new Reporter\Console\ConsolePrinter(\fopen(
+                    'php://stdout',
+                    'wb'
+                )),
                 new Reporter\Console\DurationFormatter(),
                 $maximumDuration,
                 $maximumCount
@@ -337,13 +339,7 @@ public function executeAfterLastTest(): void
                 return;
             }
 
-            $report = $this->reporter->report($slowTestList);
-
-            if ('' === $report) {
-                return;
-            }
-
-            echo $report;
+            $this->reporter->report($slowTestList);
         }
 
         private function resolveMaximumDuration(string $test): MaximumDuration
@@ -465,11 +461,11 @@ public function bootstrap(
                 new Subscriber\TestRunner\ExecutionFinishedSubscriber(
                     $collector,
                     new Reporter\Console\ConsoleReporter(
+                        new Reporter\Console\ConsolePrinter($output),
                         new Reporter\Console\DurationFormatter(),
                         $maximumDuration,
                         $maximumCount
-                    ),
-                    $output
+                    )
                 )
             );
         }
diff --git a/src/Reporter/Console/ConsolePrinter.php b/src/Reporter/Console/ConsolePrinter.php
new file mode 100644
index 000000000..5c9e36867
--- /dev/null
+++ b/src/Reporter/Console/ConsolePrinter.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2021-2026 Andreas Möller
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE.md file that was distributed with this source code.
+ *
+ * @see https://github.com/ergebnis/phpunit-slow-test-detector
+ */
+
+namespace Ergebnis\PHPUnit\SlowTestDetector\Reporter\Console;
+
+use Ergebnis\PHPUnit\SlowTestDetector\Exception;
+
+/**
+ * @internal
+ */
+final class ConsolePrinter
+{
+    /**
+     * @var resource
+     */
+    private $output;
+
+    /**
+     * @param resource $output
+     *
+     * @throws Exception\InvalidOutput
+     */
+    public function __construct($output)
+    {
+        if (!\is_resource($output)) {
+            throw Exception\InvalidOutput::notResource($output);
+        }
+
+        $this->output = $output;
+    }
+
+    public function printLine(string $line)
+    {
+        \fwrite(
+            $this->output,
+            $line . "\n"
+        );
+    }
+}
diff --git a/src/Reporter/Console/ConsoleReporter.php b/src/Reporter/Console/ConsoleReporter.php
index b7e3cda3c..e7577c33e 100644
--- a/src/Reporter/Console/ConsoleReporter.php
+++ b/src/Reporter/Console/ConsoleReporter.php
@@ -26,6 +26,11 @@
  */
 final class ConsoleReporter implements Reporter\Reporter
 {
+    /**
+     * @var ConsolePrinter
+     */
+    private $printer;
+
     /**
      * @var DurationFormatter
      */
@@ -42,36 +47,18 @@ final class ConsoleReporter implements Reporter\Reporter
     private $maximumCount;
 
     public function __construct(
+        ConsolePrinter $printer,
         DurationFormatter $durationFormatter,
         MaximumDuration $maximumDuration,
         MaximumCount $maximumCount
     ) {
+        $this->printer = $printer;
         $this->durationFormatter = $durationFormatter;
         $this->maximumDuration = $maximumDuration;
         $this->maximumCount = $maximumCount;
     }
 
-    public function report(SlowTestList $slowTestList): string
-    {
-        $lines = \iterator_to_array(
-            $this->lines($slowTestList),
-            false
-        );
-
-        if ([] === $lines) {
-            return '';
-        }
-
-        return \implode(
-            "\n",
-            $lines
-        );
-    }
-
-    /**
-     * @return \Generator<int, string>
-     */
-    private function lines(SlowTestList $slowTestList): \Generator
+    public function report(SlowTestList $slowTestList)
     {
         $slowTestCount = $slowTestList->count();
 
@@ -84,7 +71,7 @@ private function lines(SlowTestList $slowTestList): \Generator
             ->limitTo($this->maximumCount);
 
         if ($slowTestListThatWillBeReported->hasSlowTestWithMaximumDurationDifferentFrom($this->maximumDuration->toDuration())) {
-            yield from $this->reportWithCustomAndGlobalMaximumDuration(
+            $this->reportWithCustomAndGlobalMaximumDuration(
                 $slowTestCount,
                 $slowTestListThatWillBeReported
             );
@@ -92,22 +79,19 @@ private function lines(SlowTestList $slowTestList): \Generator
             return;
         }
 
-        yield from $this->reportWithGlobalMaximumDuration(
+        $this->reportWithGlobalMaximumDuration(
             $slowTestCount,
             $slowTestListThatWillBeReported
         );
     }
 
-    /**
-     * @return \Generator<int, string>
-     */
     private function reportWithCustomAndGlobalMaximumDuration(
         Count $slowTestCount,
         SlowTestList $slowTestListThatWillBeReported
-    ): \Generator {
-        yield '';
+    ) {
+        $this->printer->printLine('');
 
-        yield '';
+        $this->printer->printLine('');
 
         $unit = Unit::fromDurations(
             $this->maximumDuration->toDuration(),
@@ -126,14 +110,14 @@ private function reportWithCustomAndGlobalMaximumDuration(
             $this->maximumDuration->toDuration()
         );
 
-        yield \sprintf(
+        $this->printer->printLine(\sprintf(
             'Detected %d %s where the duration exceeded a custom or the global maximum duration (%s).',
             $slowTestCount->toInt(),
             $slowTestCount->equals(Count::fromInt(1)) ? 'test' : 'tests',
             $globalMaximumDurationFormatted
-        );
+        ));
 
-        yield '';
+        $this->printer->printLine('');
 
         $numberColumnWidth = \strlen((string) $slowTestListThatWillBeReported->count()->toInt());
         $durationColumnWidth = $this->durationColumnWidth(
@@ -156,12 +140,12 @@ private function reportWithCustomAndGlobalMaximumDuration(
             $durationColumnWidth + 1 + $durationColumnWidth
         );
 
-        yield \sprintf(
+        $this->printer->printLine(\sprintf(
             $headerTemplate,
             '#',
             'Duration',
             'Test'
-        );
+        ));
 
         $subHeaderTemplate = \sprintf(
             '%%%ds %%-%ds %%s',
@@ -169,19 +153,19 @@ private function reportWithCustomAndGlobalMaximumDuration(
             $durationColumnWidth
         );
 
-        yield \sprintf(
+        $this->printer->printLine(\sprintf(
             $subHeaderTemplate,
             '',
             'Actual',
             'Maximum'
-        );
+        ));
 
         $separator = \str_repeat(
             '-',
             $numberColumnWidth + 1 + $durationColumnWidth + 1 + $durationColumnWidth + 1 + $testDescriptionColumnWidth
         );
 
-        yield $separator;
+        $this->printer->printLine($separator);
 
         $rowTemplate = \sprintf(
             '%%%dd %%%ds %%%ds %%s',
@@ -207,36 +191,33 @@ private function reportWithCustomAndGlobalMaximumDuration(
                 );
             }
 
-            yield \sprintf(
+            $this->printer->printLine(\sprintf(
                 $rowTemplate,
                 $i + 1,
                 $actualDurationFormatted,
                 $maximumDurationFormatted,
                 $slowTest->testDescription()->toString()
-            );
+            ));
         }
 
-        yield $separator;
+        $this->printer->printLine($separator);
 
-        yield from $this->legend(
+        $this->printLegend(
             $unit,
             $numberColumnWidth + 1,
             $durationColumnWidth
         );
 
-        yield from $this->footer($slowTestCount);
+        $this->printFooter($slowTestCount);
     }
 
-    /**
-     * @return \Generator<int, string>
-     */
     private function reportWithGlobalMaximumDuration(
         Count $slowTestCount,
         SlowTestList $slowTestListThatWillBeReported
-    ): \Generator {
-        yield '';
+    ) {
+        $this->printer->printLine('');
 
-        yield '';
+        $this->printer->printLine('');
 
         $unit = Unit::fromDurations(
             $this->maximumDuration->toDuration(),
@@ -250,14 +231,14 @@ private function reportWithGlobalMaximumDuration(
             $this->maximumDuration->toDuration()
         );
 
-        yield \sprintf(
+        $this->printer->printLine(\sprintf(
             'Detected %d %s where the duration exceeded the global maximum duration (%s).',
             $slowTestCount->toInt(),
             $slowTestCount->equals(Count::fromInt(1)) ? 'test' : 'tests',
             $globalMaximumDurationFormatted
-        );
+        ));
 
-        yield '';
+        $this->printer->printLine('');
 
         $numberColumnWidth = \strlen((string) $slowTestListThatWillBeReported->count()->toInt());
         $durationColumnWidth = $this->durationColumnWidth(
@@ -275,19 +256,19 @@ private function reportWithGlobalMaximumDuration(
             $durationColumnWidth
         );
 
-        yield \sprintf(
+        $this->printer->printLine(\sprintf(
             $headerTemplate,
             '#',
             'Duration',
             'Test'
-        );
+        ));
 
         $separator = \str_repeat(
             '-',
             $numberColumnWidth + 1 + $durationColumnWidth + 1 + $testDescriptionColumnWidth
         );
 
-        yield $separator;
+        $this->printer->printLine($separator);
 
         $rowTemplate = \sprintf(
             '%%%dd %%%ds %%s',
@@ -301,23 +282,23 @@ private function reportWithGlobalMaximumDuration(
                 $slowTest->duration()
             );
 
-            yield \sprintf(
+            $this->printer->printLine(\sprintf(
                 $rowTemplate,
                 $i + 1,
                 $durationFormatted,
                 $slowTest->testDescription()->toString()
-            );
+            ));
         }
 
-        yield $separator;
+        $this->printer->printLine($separator);
 
-        yield from $this->legend(
+        $this->printLegend(
             $unit,
             $numberColumnWidth + 1,
             $durationColumnWidth
         );
 
-        yield from $this->footer($slowTestCount);
+        $this->printFooter($slowTestCount);
     }
 
     private function durationColumnWidth(
@@ -335,14 +316,11 @@ private function durationColumnWidth(
         );
     }
 
-    /**
-     * @return \Generator<int, string>
-     */
-    private function legend(
+    private function printLegend(
         Unit $unit,
         int $columnStart,
         int $columnWidth
-    ): \Generator {
+    ) {
         $durationOfZero = Duration::fromSecondsAndNanoseconds(
             0,
             0
@@ -358,33 +336,30 @@ private function legend(
             $columnStart + $columnWidth - \strlen($durationOfZeroFormatted)
         );
 
-        yield $padding . $durationOfZeroFormatted;
+        $this->printer->printLine($padding . $durationOfZeroFormatted);
 
         if ($unit->equals(Unit::hours())) {
-            yield $padding . ' │  │  └─── seconds';
+            $this->printer->printLine($padding . ' │  │  └─── seconds');
 
-            yield $padding . ' │  └────── minutes';
+            $this->printer->printLine($padding . ' │  └────── minutes');
 
-            yield $padding . ' └───────── hours';
+            $this->printer->printLine($padding . ' └───────── hours');
 
             return;
         }
 
         if ($unit->equals(Unit::minutes())) {
-            yield $padding . ' │  └─── seconds';
+            $this->printer->printLine($padding . ' │  └─── seconds');
 
-            yield $padding . ' └────── minutes';
+            $this->printer->printLine($padding . ' └────── minutes');
 
             return;
         }
 
-        yield $padding . ' └─── seconds';
+        $this->printer->printLine($padding . ' └─── seconds');
     }
 
-    /**
-     * @return \Generator<int, string>
-     */
-    private function footer(Count $slowTestCount): \Generator
+    private function printFooter(Count $slowTestCount)
     {
         $additionalSlowTestCount = Count::fromInt(\max(
             0,
@@ -395,15 +370,17 @@ private function footer(Count $slowTestCount): \Generator
             return;
         }
 
-        yield '';
+        $this->printer->printLine('');
 
         if ($additionalSlowTestCount->equals(Count::fromInt(1))) {
-            yield 'There is 1 additional slow test that is not listed here.';
-        } else {
-            yield \sprintf(
-                'There are %d additional slow tests that are not listed here.',
-                $additionalSlowTestCount->toInt()
-            );
+            $this->printer->printLine('There is 1 additional slow test that is not listed here.');
+
+            return;
         }
+
+        $this->printer->printLine(\sprintf(
+            'There are %d additional slow tests that are not listed here.',
+            $additionalSlowTestCount->toInt()
+        ));
     }
 }
diff --git a/src/Reporter/Reporter.php b/src/Reporter/Reporter.php
index e6c84c4a2..9e522504b 100644
--- a/src/Reporter/Reporter.php
+++ b/src/Reporter/Reporter.php
@@ -20,5 +20,5 @@
  */
 interface Reporter
 {
-    public function report(SlowTestList $slowTestList): string;
+    public function report(SlowTestList $slowTestList);
 }
diff --git a/src/Subscriber/TestRunner/ExecutionFinishedSubscriber.php b/src/Subscriber/TestRunner/ExecutionFinishedSubscriber.php
index 22c58988c..66def6fad 100644
--- a/src/Subscriber/TestRunner/ExecutionFinishedSubscriber.php
+++ b/src/Subscriber/TestRunner/ExecutionFinishedSubscriber.php
@@ -32,22 +32,12 @@ final class ExecutionFinishedSubscriber implements Event\TestRunner\ExecutionFin
      */
     private $reporter;
 
-    /**
-     * @var resource
-     */
-    private $output;
-
-    /**
-     * @param resource $output
-     */
     public function __construct(
         Collector\Collector $collector,
-        Reporter\Reporter $reporter,
-        $output
+        Reporter\Reporter $reporter
     ) {
         $this->collector = $collector;
         $this->reporter = $reporter;
-        $this->output = $output;
     }
 
     /**
@@ -61,15 +51,6 @@ public function notify(Event\TestRunner\ExecutionFinished $event): void
             return;
         }
 
-        $report = $this->reporter->report($slowTestList);
-
-        if ('' === $report) {
-            return;
-        }
-
-        \fwrite(
-            $this->output,
-            $report
-        );
+        $this->reporter->report($slowTestList);
     }
 }
diff --git a/test/Unit/Exception/InvalidOutputTest.php b/test/Unit/Exception/InvalidOutputTest.php
new file mode 100644
index 000000000..ea1d18b49
--- /dev/null
+++ b/test/Unit/Exception/InvalidOutputTest.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2021-2026 Andreas Möller
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE.md file that was distributed with this source code.
+ *
+ * @see https://github.com/ergebnis/phpunit-slow-test-detector
+ */
+
+namespace Ergebnis\PHPUnit\SlowTestDetector\Test\Unit\Exception;
+
+use Ergebnis\PHPUnit\SlowTestDetector\Exception;
+use Ergebnis\PHPUnit\SlowTestDetector\Test;
+use PHPUnit\Framework;
+
+/**
+ * @covers \Ergebnis\PHPUnit\SlowTestDetector\Exception\InvalidOutput
+ */
+final class InvalidOutputTest extends Framework\TestCase
+{
+    use Test\Util\Helper;
+
+    /**
+     * @dataProvider provideOutput
+     *
+     * @param mixed $output
+     */
+    public function testNotResourceReturnsException($output)
+    {
+        $exception = Exception\InvalidOutput::notResource($output);
+
+        $message = \sprintf(
+            'Output needs to be a resource, got %s instead.',
+            \is_object($output) ? \get_class($output) : \gettype($output)
+        );
+
+        self::assertSame($message, $exception->getMessage());
+    }
+
+    /**
+     * @return \Generator<string, array{0: mixed}>
+     */
+    public static function provideOutput(): iterable
+    {
+        $faker = self::faker();
+
+        $values = [
+            'boolean' => $faker->boolean(),
+            'integer' => $faker->numberBetween(),
+            'string' => $faker->sentence(),
+            'array' => $faker->words(),
+            'null' => null,
+            'object' => new \stdClass(),
+        ];
+
+        foreach ($values as $key => $output) {
+            yield $key => [
+                $output,
+            ];
+        }
+    }
+}
diff --git a/test/Unit/Reporter/Console/ConsolePrinterTest.php b/test/Unit/Reporter/Console/ConsolePrinterTest.php
new file mode 100644
index 000000000..f3c4e7a03
--- /dev/null
+++ b/test/Unit/Reporter/Console/ConsolePrinterTest.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2021-2026 Andreas Möller
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE.md file that was distributed with this source code.
+ *
+ * @see https://github.com/ergebnis/phpunit-slow-test-detector
+ */
+
+namespace Ergebnis\PHPUnit\SlowTestDetector\Test\Unit\Reporter\Console;
+
+use Ergebnis\PHPUnit\SlowTestDetector\Reporter;
+use Ergebnis\PHPUnit\SlowTestDetector\Test;
+use PHPUnit\Framework;
+
+/**
+ * @covers \Ergebnis\PHPUnit\SlowTestDetector\Reporter\Console\ConsolePrinter
+ */
+final class ConsolePrinterTest extends Framework\TestCase
+{
+    use Test\Util\Helper;
+
+    public function testPrintLineWritesLineFollowedByNewlineToResource()
+    {
+        $line = self::faker()->sentence();
+
+        $output = \fopen(
+            'php://memory',
+            'rb+'
+        );
+
+        $printer = new Reporter\Console\ConsolePrinter($output);
+
+        $printer->printLine($line);
+
+        \rewind($output);
+
+        $expectedOutput = \sprintf(
+            "%s\n",
+            $line
+        );
+
+        self::assertSame($expectedOutput, \stream_get_contents($output));
+    }
+}
diff --git a/test/Unit/Reporter/Console/ConsoleReporterTest.php b/test/Unit/Reporter/Console/ConsoleReporterTest.php
index 281c27c82..a132bdec8 100644
--- a/test/Unit/Reporter/Console/ConsoleReporterTest.php
+++ b/test/Unit/Reporter/Console/ConsoleReporterTest.php
@@ -33,6 +33,7 @@
  * @uses \Ergebnis\PHPUnit\SlowTestDetector\Duration
  * @uses \Ergebnis\PHPUnit\SlowTestDetector\MaximumCount
  * @uses \Ergebnis\PHPUnit\SlowTestDetector\MaximumDuration
+ * @uses \Ergebnis\PHPUnit\SlowTestDetector\Reporter\Console\ConsolePrinter
  * @uses \Ergebnis\PHPUnit\SlowTestDetector\Reporter\Console\DurationFormatter
  * @uses \Ergebnis\PHPUnit\SlowTestDetector\Reporter\Console\Unit
  * @uses \Ergebnis\PHPUnit\SlowTestDetector\SlowTest
@@ -44,41 +45,57 @@ final class ConsoleReporterTest extends Framework\TestCase
 {
     use Test\Util\Helper;
 
-    public function testReportReturnsEmptyStringWhenSlowTestListIsEmpty()
+    public function testReportPrintsNothingWhenSlowTestListIsEmpty()
     {
         $faker = self::faker();
 
         $slowTestList = SlowTestList::create();
 
+        $output = \fopen(
+            'php://memory',
+            'rb+'
+        );
+
         $reporter = new Reporter\Console\ConsoleReporter(
+            new Reporter\Console\ConsolePrinter($output),
             new Reporter\Console\DurationFormatter(),
             MaximumDuration::default(),
             MaximumCount::fromCount(Count::fromInt($faker->numberBetween(1)))
         );
 
-        $report = $reporter->report($slowTestList);
+        $reporter->report($slowTestList);
+
+        \rewind($output);
 
-        self::assertSame('', $report);
+        self::assertSame('', \stream_get_contents($output));
     }
 
     /**
      * @dataProvider provideExpectedReportMaximumDurationMaximumCountAndSlowTestList
      */
-    public function testReportReturnsReportWhenSlowTestListHasFewerSlowTestsThanMaximumCount(
+    public function testReportPrintsReportWhenSlowTestListHasFewerSlowTestsThanMaximumCount(
         string $expectedReport,
         MaximumDuration $maximumDuration,
         MaximumCount $maximumCount,
         SlowTestList $slowTestList
     ) {
+        $output = \fopen(
+            'php://memory',
+            'rb+'
+        );
+
         $reporter = new Reporter\Console\ConsoleReporter(
+            new Reporter\Console\ConsolePrinter($output),
             new Reporter\Console\DurationFormatter(),
             $maximumDuration,
             $maximumCount
         );
 
-        $report = $reporter->report($slowTestList);
+        $reporter->report($slowTestList);
+
+        \rewind($output);
 
-        self::assertSame($expectedReport, $report);
+        self::assertSame($expectedReport, \stream_get_contents($output));
     }
 
     /**
@@ -88,8 +105,10 @@ public static function provideExpectedReportMaximumDurationMaximumCountAndSlowTe
     {
         $print = static function (array $lines): string {
             return \implode(
-                "\n",
-                $lines
+                '',
+                \array_map(static function (string $line): string {
+                    return $line . "\n";
+                }, $lines)
             );
         };