Cover remaining uncovered Infection mutants

src/Pdf/Png/PhpPngHeaderUnpacker.php

@@ -0,0 +1,20 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Pdf\Png;
+
+/** @internal */
+final class PhpPngHeaderUnpacker implements PngHeaderUnpackerInterface
+{
+    public function unpack(string $data): array|false
+    {
+        return unpack(
+            'Nwidth/Nheight/CbitDepth/CcolorType/Ccompression/Cfilter/Cinterlace',
+            $data,
+        );
+    }
+}

src/Pdf/Png/PhpPngScanlineCompressor.php

@@ -0,0 +1,17 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Pdf\Png;
+
+/** @internal */
+final class PhpPngScanlineCompressor implements PngScanlineCompressorInterface
+{
+    public function compress(string $scanlines): string|false
+    {
+        return gzcompress($scanlines);
+    }
+}

src/Pdf/Png/PngHeaderUnpackerInterface.php

@@ -0,0 +1,25 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Pdf\Png;
+
+/** @internal */
+interface PngHeaderUnpackerInterface
+{
+    /**
+     * @return array{
+     *     width: int,
+     *     height: int,
+     *     bitDepth: int,
+     *     colorType: int,
+     *     compression: int,
+     *     filter: int,
+     *     interlace: int
+     * }|false
+     */
+    public function unpack(string $data): array|false;
+}

src/Pdf/Png/PngParser.php

@@ -14,6 +14,13 @@
 /** @internal */
 final readonly class PngParser implements PngParserInterface
 {
+    private PngHeaderUnpackerInterface $headerUnpacker;
+
+    public function __construct(?PngHeaderUnpackerInterface $headerUnpacker = null)
+    {
+        $this->headerUnpacker = $headerUnpacker ?? new PhpPngHeaderUnpacker();
+    }
+
     public function parse(string $contents): ParsedPngImage
     {
         $this->assertPngSignature($contents);
@@ -107,10 +114,7 @@ public function parseHeader(string $data): array
             throw new InvalidArgumentException('Unable to parse the PNG IHDR chunk.');
         }
 
-        $header = unpack(
-            'Nwidth/Nheight/CbitDepth/CcolorType/Ccompression/Cfilter/Cinterlace',
-            $data,
-        );
+        $header = $this->headerUnpacker->unpack($data);
         if (!is_array($header)) {
             throw new InvalidArgumentException('Unable to parse the PNG IHDR chunk.');
         }

src/Pdf/Png/PngPdfImageFactory.php

@@ -22,13 +22,16 @@
 {
     private PngParserInterface $parser;
     private PngScanlineUnfiltererInterface $scanlineUnfilterer;
+    private PngScanlineCompressorInterface $scanlineCompressor;
 
     public function __construct(
         ?PngParserInterface $parser = null,
         ?PngScanlineUnfiltererInterface $scanlineUnfilterer = null,
+        ?PngScanlineCompressorInterface $scanlineCompressor = null,
     ) {
         $this->parser = $parser ?? new PngParser();
         $this->scanlineUnfilterer = $scanlineUnfilterer ?? new PngScanlineUnfilterer();
+        $this->scanlineCompressor = $scanlineCompressor ?? new PhpPngScanlineCompressor();
     }
 
     public function create(string $contents): EmbeddedPdfImage
@@ -136,7 +139,7 @@ private function createImageDictionary(int $width, int $height, string $colorSpa
 
     private function compressScanlines(string $scanlines): string
     {
-        $compressed = gzcompress($scanlines);
+        $compressed = $this->scanlineCompressor->compress($scanlines);
         if (!is_string($compressed)) {
             throw new InvalidArgumentException('PNG scanlines could not be compressed.');
         }

src/Pdf/Png/PngScanlineCompressorInterface.php

@@ -0,0 +1,14 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Pdf\Png;
+
+/** @internal */
+interface PngScanlineCompressorInterface
+{
+    public function compress(string $scanlines): string|false;
+}

tests/Unit/Pdf/FilesystemImageSourceReaderTest.php

@@ -42,6 +42,22 @@ public function run(callable $operation, string $message): mixed
         self::assertSame('converted-contents', $reader->read($path));
     }
 
+    public function testReadRejectsNonStringWarningConverterResult(): void
+    {
+        $reader = new FilesystemImageSourceReader(new class implements WarningToExceptionConverterInterface {
+            public function run(callable $operation, string $message): mixed
+            {
+                return false;
+            }
+        });
+        $path = $this->createTemporaryFile('png', 'disk-contents');
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage(sprintf('Failed to read image source "%s".', $path));
+
+        $reader->read($path);
+    }
+
     public function testReadRejectsMissingSources(): void
     {
         $reader = new FilesystemImageSourceReader();

tests/Unit/Pdf/Png/PhpPngHeaderUnpackerTest.php

@@ -0,0 +1,32 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Tests\Unit\Pdf\Png;
+
+use LibreSign\XObjectTemplate\Pdf\Png\PhpPngHeaderUnpacker;
+use PHPUnit\Framework\TestCase;
+
+final class PhpPngHeaderUnpackerTest extends TestCase
+{
+    public function testUnpackReturnsStructuredHeaderFields(): void
+    {
+        $unpacker = new PhpPngHeaderUnpacker();
+
+        self::assertSame(
+            [
+                'width' => 3,
+                'height' => 2,
+                'bitDepth' => 8,
+                'colorType' => 6,
+                'compression' => 0,
+                'filter' => 0,
+                'interlace' => 0,
+            ],
+            $unpacker->unpack(pack('NNCCCCC', 3, 2, 8, 6, 0, 0, 0)),
+        );
+    }
+}

tests/Unit/Pdf/Png/PhpPngScanlineCompressorTest.php

@@ -0,0 +1,25 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreSign
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreSign\XObjectTemplate\Tests\Unit\Pdf\Png;
+
+use LibreSign\XObjectTemplate\Pdf\Png\PhpPngScanlineCompressor;
+use PHPUnit\Framework\TestCase;
+
+final class PhpPngScanlineCompressorTest extends TestCase
+{
+    public function testCompressReturnsRoundTrippableCompressedScanlines(): void
+    {
+        $compressor = new PhpPngScanlineCompressor();
+        $scanlines = "\x00\xff\x00\x00\x00\x00\xff\x00";
+
+        $compressed = $compressor->compress($scanlines);
+
+        self::assertIsString($compressed);
+        self::assertSame($scanlines, gzuncompress($compressed));
+    }
+}

tests/Unit/Pdf/Png/PngParserTest.php

@@ -7,6 +7,7 @@
 
 namespace LibreSign\XObjectTemplate\Tests\Unit\Pdf\Png;
 
+use LibreSign\XObjectTemplate\Pdf\Png\PngHeaderUnpackerInterface;
 use LibreSign\XObjectTemplate\Pdf\Png\PngParser;
 use LibreSign\XObjectTemplate\Tests\Support\PngFixtureFactory;
 use PHPUnit\Framework\TestCase;
@@ -157,6 +158,21 @@ public function testParseHeaderRejectsUnexpectedHeaderLength(): void
         $parser->parseHeader('short-header');
     }
 
+    public function testParseHeaderRejectsUnpackFailures(): void
+    {
+        $parser = new PngParser(new class implements PngHeaderUnpackerInterface {
+            public function unpack(string $data): array|false
+            {
+                return false;
+            }
+        });
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Unable to parse the PNG IHDR chunk.');
+
+        $parser->parseHeader(pack('NNCCCCC', 1, 1, 8, 2, 0, 0, 0));
+    }
+
     public function testParseRejectsMissingTrailerChunkWhenTrailingBytesAreTooShort(): void
     {
         $parser = new PngParser();

tests/Unit/Pdf/Png/PngPdfImageFactoryTest.php

@@ -10,6 +10,7 @@
 use LibreSign\XObjectTemplate\Pdf\Png\ParsedPngImage;
 use LibreSign\XObjectTemplate\Pdf\Png\PngParserInterface;
 use LibreSign\XObjectTemplate\Pdf\Png\PngPdfImageFactory;
+use LibreSign\XObjectTemplate\Pdf\Png\PngScanlineCompressorInterface;
 use LibreSign\XObjectTemplate\Pdf\Png\PngScanlineUnfiltererInterface;
 use PHPUnit\Framework\TestCase;
 
@@ -85,4 +86,56 @@ public function unfilter(string $idat, int $height, int $rowLength, int $bytesPe
 
         $factory->create('not-a-real-png');
     }
+
+    public function testCreateRejectsTruncatedAlphaPixelData(): void
+    {
+        $factory = new PngPdfImageFactory(
+            new class implements PngParserInterface {
+                public function parse(string $contents): ParsedPngImage
+                {
+                    return new ParsedPngImage(1, 1, 6, 'ignored-compressed-idat');
+                }
+            },
+            new class implements PngScanlineUnfiltererInterface {
+                public function unfilter(string $idat, int $height, int $rowLength, int $bytesPerPixel): array
+                {
+                    return ["\xff\x00\x00"];
+                }
+            },
+        );
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('PNG row data is truncated.');
+
+        $factory->create('not-a-real-png');
+    }
+
+    public function testCreateRejectsCompressionFailuresForAlphaImages(): void
+    {
+        $factory = new PngPdfImageFactory(
+            new class implements PngParserInterface {
+                public function parse(string $contents): ParsedPngImage
+                {
+                    return new ParsedPngImage(1, 1, 6, 'ignored-compressed-idat');
+                }
+            },
+            new class implements PngScanlineUnfiltererInterface {
+                public function unfilter(string $idat, int $height, int $rowLength, int $bytesPerPixel): array
+                {
+                    return ["\xff\x00\x00\x80"];
+                }
+            },
+            new class implements PngScanlineCompressorInterface {
+                public function compress(string $scanlines): string|false
+                {
+                    return false;
+                }
+            },
+        );
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('PNG scanlines could not be compressed.');
+
+        $factory->create('not-a-real-png');
+    }
 }

tests/Unit/Pdf/Png/PngScanlineUnfiltererTest.php

@@ -35,6 +35,21 @@ public function run(callable $operation, string $message): mixed
         self::assertSame(["\x7f"], $unfilterer->unfilter('ignored-idat', 1, 1, 1));
     }
 
+    public function testUnfilterRejectsNonStringWarningConverterResult(): void
+    {
+        $unfilterer = new PngScanlineUnfilterer(new class implements WarningToExceptionConverterInterface {
+            public function run(callable $operation, string $message): mixed
+            {
+                return false;
+            }
+        });
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('PNG image data could not be decompressed.');
+
+        $unfilterer->unfilter('ignored-idat', 1, 1, 1);
+    }
+
     public function testUnfilterRejectsMissingRowFilterBytes(): void
     {
         $unfilterer = new PngScanlineUnfilterer();