Support baseline configuration

README.md

@@ -122,4 +122,20 @@ vendor/bin/roave-backward-compatibility-check --help
 
 ## Configuration
 
-There are currently no configuration options available.
+The file `.roave-backward-compatibility-check.xml` is read from the current working directory (when it exists) and sets configuration for the command.
+
+It's expected to be an XML file that follows our [schema](resources/schema.xsd):
+
+**Example:**
+
+```xml
+<?xml version="1.0" encoding="UTF-8" ?>
+<roave-bc-check
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="vendor/roave/backward-compatibility-check/resources/schema.xsd">
+    <baseline>
+        <ignored-regex>#\[BC\] CHANGED: The parameter \$a of of TestArtifact\\TheClass\#method\(\)#</ignored-regex>
+        <ignored-regex>#\[BC\] CHANGED: The parameter \$b of of TestArtifact\\TheClass\#method2\(\)#</ignored-regex>
+    </baseline>
+</roave-bc-check>
+```

Resources/schema.xsd

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
+    <xs:annotation>
+        <xs:appinfo source="https://github.com/Roave/BackwardCompatibilityCheck"/>
+
+        <xs:documentation source="https://github.com/Roave/BackwardCompatibilityCheck">
+            This schema file defines the structure for the XML configuration file of roave/backward-compatibility-check.
+        </xs:documentation>
+    </xs:annotation>
+
+    <xs:element name="roave-bc-check" type="bcCheckType" />
+
+    <xs:complexType name="bcCheckType">
+        <xs:sequence>
+            <xs:element name="baseline" type="baselineType" minOccurs="0" />
+        </xs:sequence>
+    </xs:complexType>
+
+    <xs:complexType name="baselineType">
+        <xs:sequence>
+            <xs:element name="ignored-regex" minOccurs="0" maxOccurs="unbounded" type="ignore-pattern"  />
+        </xs:sequence>
+    </xs:complexType>
+
+    <xs:simpleType name="ignore-pattern">
+        <xs:restriction base="xs:string">
+            <xs:pattern value="#.+#" />
+        </xs:restriction>
+    </xs:simpleType>
+</xs:schema>

box.json.dist

@@ -10,6 +10,7 @@
     "main": "bin/roave-backward-compatibility-check.php",
     "output": "dist/roave-backward-compatibility-check.phar",
     "files-bin": [
+        "Resources/schema.xsd",
         "LICENSE",
         "vendor/composer/composer/LICENSE"
     ],

composer.json

@@ -3,6 +3,10 @@
     "description": "Tool to compare two revisions of a public API to check for BC breaks",
     "require": {
         "php": "~8.2.0 || ~8.3.0",
+        "ext-dom": "*",
+        "ext-json": "*",
+        "ext-libxml": "*",
+        "ext-simplexml": "*",
         "azjezz/psl": "^3.0.2",
         "composer/composer": "^2.7.6",
         "nikic/php-parser": "^4.19.1",

src/Baseline.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Roave\BackwardCompatibility;
+
+use function array_values;
+use function preg_match;
+
+/** @psalm-immutable */
+final class Baseline
+{
+    /** @psalm-param list<non-empty-string> $ignoredChanges */
+    private function __construct(private readonly array $ignoredChanges = [])
+    {
+    }
+
+    public static function empty(): self
+    {
+        return new self();
+    }
+
+    /** @psalm-param list<non-empty-string> $ignoredChanges */
+    public static function fromList(string ...$ignoredChanges): self
+    {
+        return new self(array_values($ignoredChanges));
+    }
+
+    public function ignores(Change $change): bool
+    {
+        $changeDescription = $change->__toString();
+
+        foreach ($this->ignoredChanges as $ignoredChangeRegex) {
+            if (preg_match($ignoredChangeRegex, $changeDescription) === 1) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}

src/Changes.php

@@ -67,6 +67,23 @@ public function mergeWith(self $other): self
         return $instance;
     }
 
+    public function applyBaseline(Baseline $baseline): self
+    {
+        $instance = new self([]);
+
+        $instance->unBufferedChanges = (function () use ($baseline): Generator {
+            foreach ($this as $change) {
+                if ($baseline->ignores($change)) {
+                    continue;
+                }
+
+                yield $change;
+            }
+        })();
+
+        return $instance;
+    }
+
     /**
      * {@inheritDoc}
      *

src/Command/AssertBackwardsCompatible.php

@@ -114,7 +114,9 @@ public function execute(InputInterface $input, OutputInterface $output): int
         $stdErr = $output->getErrorOutput();
 
         // @todo fix flaky assumption about the path of the source repo...
-        $sourceRepo = CheckedOutRepository::fromPath(Env\current_dir());
+        $currentDirectory = Env\current_dir();
+
+        $sourceRepo = CheckedOutRepository::fromPath($currentDirectory);
 
         $fromRevision = $input->getOption('from') !== null
             ? $this->parseRevisionFromInput($input, $sourceRepo)
@@ -126,6 +128,8 @@ public function execute(InputInterface $input, OutputInterface $output): int
 
         $toRevision = $this->parseRevision->fromStringForRepository($to, $sourceRepo);
 
+        $configuration = (new DetermineConfigurationFromFilesystem())($currentDirectory, $stdErr);
+
         $stdErr->writeln(Str\format(
             'Comparing from %s to %s...',
             Type\string()->coerce($fromRevision),
@@ -149,7 +153,7 @@ public function execute(InputInterface $input, OutputInterface $output): int
                     $toPath->__toString(),
                     ($this->locateDependencies)($toPath->__toString(), $includeDevelopmentDependencies),
                 ),
-            );
+            )->applyBaseline($configuration->baseline);
 
             $formatters = [
                 'console'        => new SymfonyConsoleTextFormatter($stdErr),

src/Command/DetermineConfigurationFromFilesystem.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Roave\BackwardCompatibility\Command;
+
+use Psl\Str;
+use Psl\Type;
+use Roave\BackwardCompatibility\Configuration\Configuration;
+use Roave\BackwardCompatibility\Configuration\ParseConfigurationFile;
+use Roave\BackwardCompatibility\Configuration\ParseXmlConfigurationFile;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/** @internal */
+final class DetermineConfigurationFromFilesystem
+{
+    public function __construct(
+        private readonly ParseConfigurationFile $parser = new ParseXmlConfigurationFile(),
+    ) {
+    }
+
+    public function __invoke(
+        string $currentDirectory,
+        OutputInterface $stdErr,
+    ): Configuration {
+        $configuration = $this->parser->parse($currentDirectory);
+
+        if ($configuration->filename !== null) {
+            $stdErr->writeln(Str\format(
+                'Using "%s" as configuration file',
+                Type\string()->coerce($configuration->filename),
+            ));
+        }
+
+        return $configuration;
+    }
+}

src/Configuration/Configuration.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Roave\BackwardCompatibility\Configuration;
+
+use Roave\BackwardCompatibility\Baseline;
+
+/** @psalm-immutable */
+final class Configuration
+{
+    private function __construct(
+        public readonly Baseline $baseline,
+        public readonly string|null $filename,
+    ) {
+    }
+
+    public static function default(): self
+    {
+        return new self(Baseline::empty(), null);
+    }
+
+    public static function fromFile(Baseline $baseline, string $filename): self
+    {
+        return new self($baseline, $filename);
+    }
+}

src/Configuration/InvalidConfigurationStructure.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Roave\BackwardCompatibility\Configuration;
+
+use LibXMLError;
+use RuntimeException;
+
+use function sprintf;
+use function trim;
+
+use const PHP_EOL;
+
+/** @internal */
+final class InvalidConfigurationStructure extends RuntimeException
+{
+    /** @param list<LibXMLError> $errors */
+    public static function fromLibxmlErrors(array $errors): self
+    {
+        $message = 'The provided configuration is invalid, errors:' . PHP_EOL;
+
+        foreach ($errors as $error) {
+            $message .= sprintf(
+                ' - [Line %d] %s' . PHP_EOL,
+                $error->line,
+                trim($error->message),
+            );
+        }
+
+        return new self($message);
+    }
+}

src/Configuration/ParseConfigurationFile.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Roave\BackwardCompatibility\Configuration;
+
+interface ParseConfigurationFile
+{
+    /** @throws InvalidConfigurationStructure When an incorrect file was found on the directory. */
+    public function parse(string $currentDirectory): Configuration;
+}

src/Configuration/ParseXmlConfigurationFile.php

@@ -0,0 +1,75 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Roave\BackwardCompatibility\Configuration;
+
+use DOMDocument;
+use Psl\File;
+use Roave\BackwardCompatibility\Baseline;
+use SimpleXMLElement;
+
+use function assert;
+use function libxml_get_errors;
+use function libxml_use_internal_errors;
+
+/** @internal */
+final class ParseXmlConfigurationFile implements ParseConfigurationFile
+{
+    private const CONFIGURATION_FILENAME = '.roave-backward-compatibility-check.xml';
+
+    private const SCHEMA = __DIR__ . '/../../Resources/schema.xsd';
+
+    public function parse(string $currentDirectory): Configuration
+    {
+        $filename = $currentDirectory . '/' . self::CONFIGURATION_FILENAME;
+
+        try {
+            $xmlContents = File\read($filename);
+
+            $this->validateStructure($xmlContents);
+        } catch (File\Exception\InvalidArgumentException) {
+            return Configuration::default();
+        }
+
+        $configuration = new SimpleXMLElement($xmlContents);
+
+        return Configuration::fromFile(
+            $this->parseBaseline($configuration),
+            $filename,
+        );
+    }
+
+    private function validateStructure(string $xmlContents): void
+    {
+        $previousConfiguration = libxml_use_internal_errors(true);
+
+        $xmlDocument = new DOMDocument();
+        $xmlDocument->loadXML($xmlContents);
+
+        $configurationIsValid = $xmlDocument->schemaValidate(self::SCHEMA);
+
+        $parsingErrors = libxml_get_errors();
+        libxml_use_internal_errors($previousConfiguration);
+
+        if ($configurationIsValid) {
+            return;
+        }
+
+        throw InvalidConfigurationStructure::fromLibxmlErrors($parsingErrors);
+    }
+
+    private function parseBaseline(SimpleXMLElement $element): Baseline
+    {
+        $ignoredItems = [];
+
+        foreach ($element->xpath('baseline/ignored-regex') ?? [] as $node) {
+            $ignoredItem = (string) $node;
+
+            assert($ignoredItem !== '');
+            $ignoredItems[] = $ignoredItem;
+        }
+
+        return Baseline::fromList(...$ignoredItems);
+    }
+}