ddeboer · Jan 11, 2021 · Jan 13, 2021 · Jan 13, 2021 · Jan 13, 2021 · May 22, 2021
diff --git a/.envrc b/.envrc
@@ -0,0 +1,2 @@
+use nix
+watch_file flake.nix flake.lock
diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
@@ -0,0 +1,68 @@
+# This file lints the code and runs tests.
+name: CI
+
+on:
+  pull_request:
+  push:
+
+env:
+  COMPOSER_FLAGS: "--ansi --no-interaction --no-progress --no-suggest --prefer-dist"
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php:
+          - '8.4'
+          - '8.3'
+          - '8.2'
+          - '8.1'
+          - '8.0'
+          - '7.4'
+        include:
+          - php: '7.4'
+            cs_fixer: true
+          - php: '8.0'
+            phpstan: true
+    name: 'Check with PHP ${{ matrix.php }}'
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@v31
+
+      - name: Set up Nix cache
+        uses: cachix/cachix-action@v16
+        with:
+          # Use cache from https://github.com/fossar/nix-phps
+          name: fossar
+
+      - name: Update flake.nix to match the current CI job from matrix
+        run: sed -i 's/matrix.phpPackage = "php";/matrix.phpPackage = builtins.replaceStrings ["."] [""] "php${{ matrix.php }}";/' flake.nix
+
+      - name: Get Composer Cache Directory
+        id: composer-cache
+        run: |
+          echo "dir=$(composer config cache-files-dir)" >> "$GITHUB_OUTPUT"
+
+      - uses: actions/cache@v4
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-composer-
+
+      - name: Install dependencies
+        run: nix-shell --run 'composer install'
+
+      - name: Lint source code
+        if: matrix.cs_fixer
+        run: nix-shell --run 'composer cs-check'
+
+      - name: Run unit tests
+        run: nix-shell --run 'composer test'
+
+      - name: Statically analyze source code
+        if: matrix.phpstan
+        run: nix-shell --run 'composer phpstan'
diff --git a/.gitignore b/.gitignore
@@ -1,2 +1,6 @@
 composer.lock
-vendor
+vendor/
+.direnv/
+.php-cs-fixer.cache
+.phpunit.result.cache
+phpstan.neon
diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
@@ -0,0 +1,24 @@
+<?php
+
+$finder = PhpCsFixer\Finder::create()
+    ->in(__DIR__);
+
+$rules = [
+    '@Symfony' => true,
+    '@PHP74Migration' => true,
+    '@PHP74Migration:risky' => true,
+    'phpdoc_to_property_type' => true,
+    // 'phpdoc_to_param_type' => true, // requires PHP 8.0
+    'phpdoc_to_return_type' => true,
+    // overwrite some Symfony rules
+    'concat_space' => ['spacing' => 'one'],
+    'phpdoc_align' => false,
+    'yoda_style' => false,
+];
+
+$config = new PhpCsFixer\Config();
+
+return $config
+    ->setRules($rules)
+    ->setRiskyAllowed(true)
+    ->setFinder($finder);
diff --git a/.travis.yml b/.travis.yml
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -0,0 +1,34 @@
+# Transcoder Changelog
+
+This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [3.0.0] – 2025-03-15
+
+- Mb: Make encoding detection stricter.
+- Raise minimum PHP version to 7.4.0.
+
+
+## [2.0.0] – 2023-03-07
+
+- Iconv: Fix warning on PHP 8.2 when passing `null` as source encoding.
+- Raise minimum PHP version to 7.2.5.
+- Add parameter and return type hints.
+
+
+## [1.0.1] – 2021-05-23
+
+The project has been revived and is now available under the name [`fossar/transcoder`](https://packagist.org/packages/fossar/transcoder). This is a first release since the fork.
+
+- Iconv: Fixed detection of unsupported encoding on PHP 8.
+- Mb: Restored the ability to pass “auto” as input language on PHP ≥ 7.3.
+- Fixed the pairing of setting and restoring error handlers in the transcoders so that they do not clear handlers that they did not create nor do they leave any around when something unexpected happens.
+- Fixed creating `Transcoder` with just `mbstring` (without `iconv`).
+- Clarified that “auto-detection” does not actually work.
+- Fixed various minor test issues.
+- Cleaned up coding style.
+- Added Nix expression for easier development and sharing the environment with CI.
+- Switched to GitHub Actions for CI and added more PHP versions.
+
+[3.0.0]: https://github.com/fossar/transcoder/compare/v2.0.0...v3.0.0
+[2.0.0]: https://github.com/fossar/transcoder/compare/v1.0.1...v2.0.0
+[1.0.1]: https://github.com/fossar/transcoder/compare/1.0.0...v1.0.1
diff --git a/README.md b/README.md
@@ -1,44 +1,35 @@
-Transcoder
-==========
+# Transcoder
 
-[![Build Status](https://travis-ci.org/ddeboer/transcoder.svg?branch=master)](https://travis-ci.org/ddeboer/transcoder)
-[![Release](https://img.shields.io/github/release/ddeboer/transcoder.svg?style=flat)](https://packagist.org/packages/ddeboer/transcoder)
+[![Packagist Version](https://img.shields.io/packagist/v/fossar/transcoder)](https://packagist.org/packages/fossar/transcoder)
 
-Introduction
-------------
+## Introduction
 
-This is a wrapper around PHP’s `mb_convert_encoding` and `iconv` functions.
-This library adds:
+This is a wrapper around PHP’s `mb_convert_encoding` and `iconv` functions. This library adds:
 
-* fallback from `mb` to `iconv` for unknown encodings
-* conversion of warnings to proper exceptions.
+- fallback from `mb` to `iconv` for encodings it does not support
+- conversion of warnings to proper exceptions.
 
-Installation
-------------
+## Installation
 
-The recommended way to install the Transcoder library is through 
-[Composer](http://getcomposer.org):
+The recommended way to install the Transcoder library is through [Composer](http://getcomposer.org):
 
 ```bash
-$ composer require ddeboer/transcoder
+$ composer require fossar/transcoder
 ```
 
-This command requires you to have Composer installed globally, as explained
-in the [installation chapter](https://getcomposer.org/doc/00-intro.md)
-of the Composer documentation.
+This command requires you to have Composer installed globally, as explained in the [installation chapter](https://getcomposer.org/doc/00-intro.md) of the Composer documentation.
 
-Usage
------
+## Usage
 
 ### Basics
 
-Create the right transcoder for your platform and translate some strings:
+Create the right transcoder for your platform and translate a string to ISO-8859-1 encoding:
 
 ```php
 use Ddeboer\Transcoder\Transcoder;
 
 $transcoder = Transcoder::create();
-$result = $transcoder->transcode('España');
+$result = $transcoder->transcode('España', 'iso-8859-1');
 ```
 
 You can also manually instantiate a transcoder of your liking:
@@ -47,7 +38,6 @@ You can also manually instantiate a transcoder of your liking:
 use Ddeboer\Transcoder\MbTranscoder;
 
 $transcoder = new MbTranscoder();
-
 ```
 
 Or:
@@ -60,79 +50,73 @@ $transcoder = new IconvTranscoder();
 
 ### Source encoding
 
-By default, the source encoding is detected automatically. However, you get 
-much more reliable results when you specify it explicitly:
+The second argument accepts source encoding and can actually be omitted or passed `null`.
 
 ```php
-$transcoder->transcode('España', 'iso-8859-1');
+$transcoder->transcode('España');
 ```
 
+In that case, however, the behaviour is backend-specific:
+
+- `IconvTranscoder` will use the encoding of the current [locale](https://www.php.net/manual/en/function.setlocale.php) of the process.
+- `MbTranscoder` will try to detect encoding from a list based on the value of [`mbstring.language`](https://www.php.net/manual/en/mbstring.configuration.php#ini.mbstring.language) setting. By default, this tries ASCII, followed by UTF-8. The number of [supported languages](https://github.com/php/php-src/blob/d61d21ad57d04b91a1155153811d16ea982fa106/ext/mbstring/mbstring.c#L88-L147) is limited though and the encoding tables often overlap so the detection might be unreliable.
+
+As you can see, this is mostly useless for western languages. You will get much more reliable results when you specify the source encoding explicitly.
+
 ### Target encoding
 
 Specify a default target encoding as the first argument to `create()`:
-
 
 ```php
 use Ddeboer\Transcoder\Transcoder;
 
 $isoTranscoder = Transcoder::create('iso-8859-1');
 ```
-
-Alternatively, specify a target encoding as the third argument in a 
-`transcode()` call:
+
+Alternatively, specify a target encoding as the third argument in a `transcode()` call:
 
 ```php
 use Ddeboer\Transcoder\Transcoder;
 
-$transcoder->transcode('España', null, 'UTF-8'); 
+$transcoder->transcode('España', 'iso-8859-1', 'UTF-8');
 ```
 
 ### Error handling
 
-PHP’s `mv_convert_encoding` and `iconv` are inconvenient to use because they 
-generate notices and warnings instead of proper exceptions. This library fixes
-that:
-
+PHP’s `mv_convert_encoding` and `iconv` are inconvenient to use because they generate notices and warnings instead of proper exceptions. This library fixes that:
 
 ```php
 use Ddeboer\Transcoder\Exception\UndetectableEncodingException;
 use Ddeboer\Transcoder\Exception\UnsupportedEncodingException;
 use Ddeboer\Transcoder\Exception\IllegalCharacterException;
 
 $input = 'España';
-
-try {
-    $transcoder->transcode($input);
-} catch (UndetectableEncodingException $e) {
-    // Failed to automatically detect $input’s encoding 
-}
 
 try {
-    $transcoder->transcode($input, null, 'not-a-real-encoding');
+    $transcoder->transcode($input, 'utf-8', 'not-a-real-encoding');
 } catch (UnsupportedEncodingException $e) {
-    // ‘not-a-real-encoding’ is an unsupported encoding 
+    // ‘not-a-real-encoding’ is an unsupported encoding
 }
 
 try {
-    $transcoder->transcode('Illegal quotes: ‘ ’', null, 'iso-8859-1');
+    $transcoder->transcode('Illegal quotes: ‘ ’', 'utf-8', 'iso-8859-1');
 } catch (IllegalCharacterException $e) {
     // Curly quotes ‘ ’ are illegal in ISO-8859-1
 }
+
+try {
+    $transcoder->transcode($input);
+} catch (UndetectableEncodingException $e) {
+    // Failed to automatically detect $input’s encoding (mb) or not a valid string in current locale locale (iconv)
+}
 ```
 
 ### Transcoder fallback
 
-In general, `mb_convert_encoding` is faster than `iconv`. However, as `iconv`
-supports more encodings than `mb_convert_encoding`, it makes sense to combine 
-the two. 
+In general, `mb_convert_encoding` is faster than `iconv`. However, as `iconv` supports more encodings than `mb_convert_encoding`, it makes sense to combine the two.
 
 So, the Transcoder returned from `create()`:
 
-* uses `mb_convert_encoding` if the 
-  [mbstring](http://php.net/manual/en/book.mbstring.php) PHP extension is 
-  installed;
-* if not, it uses `iconv` instead if the 
-  [iconv](http://php.net/manual/en/book.iconv.php) extension is installed; 
-* if both the mbstring and iconv extension are available, the Transcoder will 
-  first try `mb_convert_encoding` and fall back to `iconv`.
-
+- uses `mb_convert_encoding` if the [mbstring](http://php.net/manual/en/book.mbstring.php) PHP extension is installed;
+- if not, it uses `iconv` instead if the [iconv](http://php.net/manual/en/book.iconv.php) extension is installed;
+- if both the mbstring and iconv extension are available, the Transcoder will first try `mb_convert_encoding` and fall back to `iconv`.
diff --git a/composer.json b/composer.json
@@ -1,5 +1,5 @@
 {
-    "name": "ddeboer/transcoder",
+    "name": "fossar/transcoder",
     "description": "Better encoding conversion for PHP",
     "keywords": [ "encoding", "utf-8", "iso", "mb", "iconv", "multibyte", "charset", "mb_convert_encoding" ],
     "license": "MIT",
@@ -10,14 +10,19 @@
         },
         {
             "name": "Community contributors",
-            "homepage": "https://github.com/ddeboer/transcoder/graphs/contributors"
-        }   
+            "homepage": "https://github.com/fossar/transcoder/graphs/contributors"
+        }
     ],
+    "replace": {
+        "ddeboer/transcoder": "self.version"
+    },
     "require": {
-        "php": ">=5.4.0"
+        "php": ">=7.4.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.0"
+        "symfony/phpunit-bridge": "^6.2 || ^7.0",
+        "phpstan/phpstan": "^2.1",
+        "friendsofphp/php-cs-fixer": "^3.4"
     },
     "suggest": {
         "ext-mbstring": "For using the MbTranscoder",
@@ -29,9 +34,21 @@
             "Ddeboer\\Transcoder\\Tests\\": "tests/"
         }
     },
-    "extra": {
-        "branch-alias": {
-            "dev-master": "1.0.x-dev"
+    "config": {
+        "platform": {
+            "php": "7.4.0"
         }
+    },
+    "scripts": {
+        "cs-check": "php-cs-fixer fix --verbose --dry-run --diff",
+        "cs-fix": "php-cs-fixer fix --verbose --diff",
+        "phpstan": "phpstan analyze",
+        "test": "simple-phpunit"
+    },
+    "scripts-descriptions": {
+        "cs-check": "Check coding style",
+        "cs-fix": "Fix coding style",
+        "phpstan": "Fix coding style",
+        "test": "Run all tests"
     }
 }
diff --git a/flake.lock b/flake.lock
diff --git a/flake.nix b/flake.nix
@@ -0,0 +1,59 @@
+{
+  description = "Better encoding conversion for PHP";
+
+  inputs = {
+    # For old PHP versions.
+    phps.url = "github:fossar/nix-phps";
+  };
+
+  outputs = { self, phps }:
+    let
+      # nixpkgs is a repository with software packages and some utilities.
+      # From simplicity, we inherit it from the phps flake.
+      inherit (phps.inputs) nixpkgs;
+
+      # Configure the development shell here (e.g. for CI).
+
+      # By default, we use the default PHP version from Nixpkgs.
+      matrix.phpPackage = "php";
+      # Allow easily removing some extensions for testing.
+      matrix.forbiddenExtensionNames = [
+        # "iconv"
+        # "mbstring"
+      ];
+    in
+      let
+        # We only support a single platform at the moment,
+        # since our binary cache only contains PHP packages for that.
+        system = "x86_64-linux";
+
+        # Get Nixpkgs packages for current platform.
+        pkgs = nixpkgs.legacyPackages.${system};
+
+        # Create a PHP package from the selected PHP package.
+        phpBase = phps.packages.${system}.${matrix.phpPackage};
+        php =
+          phpBase.withExtensions
+            ({ all, enabled }:
+              let
+                # Get the forbidden extensions by name.
+                forbiddenExtensions = pkgs.lib.attrVals matrix.forbiddenExtensionNames all;
+              in
+              builtins.filter (ext: !builtins.elem ext forbiddenExtensions) enabled
+            );
+      in {
+        # Expose shell environment for development.
+        devShell.${system} = pkgs.mkShell {
+          nativeBuildInputs = [
+            # Composer and PHP.
+            php
+            phpBase.packages.composer
+            pkgs.phpactor
+          ];
+
+          env = pkgs.lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
+            LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
+          };
+        };
+      };
+}
diff --git a/phpstan.dist.neon b/phpstan.dist.neon
@@ -0,0 +1,6 @@
+parameters:
+    level: max
+
+    paths:
+        - src/
+        - tests/
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
@@ -4,7 +4,7 @@
         convertErrorsToExceptions="false"
         >
     <testsuites>
-        <testsuite>
+        <testsuite name="Tests">
             <directory suffix="Test.php">./tests/</directory>
         </testsuite>
     </testsuites>

diff --git a/shell.nix b/shell.nix
@@ -0,0 +1,11 @@
+(import (
+  let
+    lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+  in
+  fetchTarball {
+    url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+    sha256 = lock.nodes.flake-compat.locked.narHash;
+  }
+) {
+  src =  ./.;
+}).shellNix
diff --git a/src/Exception/ExtensionMissingException.php b/src/Exception/ExtensionMissingException.php
@@ -1,8 +1,9 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Exception;
 
 class ExtensionMissingException extends \RuntimeException
 {
-
 }
diff --git a/src/Exception/IllegalCharacterException.php b/src/Exception/IllegalCharacterException.php
@@ -1,10 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Exception;
 
 class IllegalCharacterException extends \RuntimeException
 {
-    public function __construct($string, $warning)
+    public function __construct(string $string, string $warning)
     {
         parent::__construct(
             sprintf(

diff --git a/src/Exception/UndetectableEncodingException.php b/src/Exception/UndetectableEncodingException.php
@@ -1,10 +1,12 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Exception;
 
 class UndetectableEncodingException extends \RuntimeException
 {
-    public function __construct($string, $error)
+    public function __construct(string $string, string $error)
     {
         parent::__construct(sprintf('Encoding for %s is undetectable: %s', $string, $error));
     }

diff --git a/src/Exception/UnsupportedEncodingException.php b/src/Exception/UnsupportedEncodingException.php
@@ -1,16 +1,18 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Exception;
 
 class UnsupportedEncodingException extends \RuntimeException
 {
-    public function __construct($encoding, $message = null)
+    public function __construct(string $encoding, ?string $message = null)
     {
         $error = sprintf('Encoding %s is unsupported on this platform', $encoding);
-        if ($message) {
+        if ($message !== null) {
             $error .= ': ' . $message;
         }
-        
-        return parent::__construct($error);
+
+        parent::__construct($error);
     }
 }
diff --git a/src/IconvTranscoder.php b/src/IconvTranscoder.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder;
 
 use Ddeboer\Transcoder\Exception\ExtensionMissingException;
@@ -8,36 +10,42 @@
 
 class IconvTranscoder implements TranscoderInterface
 {
-    private $defaultEncoding;
-
-    public function __construct($defaultEncoding = 'UTF-8')
+    private string $defaultEncoding;
+
+    /**
+     * Create an Iconv-based transcoder.
+     *
+     * @throws ExtensionMissingException
+     */
+    public function __construct(string $defaultEncoding = 'UTF-8')
     {
         if (!function_exists('iconv')) {
             throw new ExtensionMissingException('iconv');
         }
-        
+
         $this->defaultEncoding = $defaultEncoding;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function transcode($string, $from = null, $to = null)
+    public function transcode(string $string, ?string $from = null, ?string $to = null): string
     {
         set_error_handler(
-            function ($no, $message) use ($string) {
-                if (1 === preg_match('/Wrong charset, conversion (.+) is/', $message, $matches)) {
+            function (int $no, string $message) use ($string): void {
+                if (1 === preg_match('/Wrong (charset|encoding), conversion (.+) is/', $message, $matches)) {
                     throw new UnsupportedEncodingException($matches[1], $message);
                 } else {
                     throw new IllegalCharacterException($string, $message);
                 }
             },
-            E_NOTICE | E_USER_NOTICE
+            E_NOTICE | E_USER_NOTICE | E_WARNING
         );
-
-        $result = iconv($from, $to ?: $this->defaultEncoding, $string);
-        restore_error_handler();
-
+
+        try {
+            $result = iconv($from ?? '', $to ?? $this->defaultEncoding, $string);
+            assert($result !== false); // For PHPStan, ensured by error handler.
+        } finally {
+            restore_error_handler();
+        }
+
         return $result;
     }
 }
diff --git a/src/MbTranscoder.php b/src/MbTranscoder.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder;
 
 use Ddeboer\Transcoder\Exception\ExtensionMissingException;
@@ -8,73 +10,83 @@
 
 class MbTranscoder implements TranscoderInterface
 {
-    private static $encodings;
-    private $defaultEncoding;
-
-    public function __construct($defaultEncoding = 'UTF-8')
+    /**
+     * @var array<string, int>
+     */
+    private static array $encodings;
+
+    private string $defaultEncoding;
+
+    /**
+     * Create a Mb-based transcoder.
+     *
+     * @throws ExtensionMissingException
+     */
+    public function __construct(string $defaultEncoding = 'UTF-8')
     {
         if (!function_exists('mb_convert_encoding')) {
             throw new ExtensionMissingException('mb');
         }
-        
-        if (null === self::$encodings) {
+
+        if (!isset(self::$encodings)) {
             self::$encodings = array_change_key_case(
                 array_flip(mb_list_encodings()),
                 CASE_LOWER
             );
         }
-        
-        $this->assertSupported($defaultEncoding);
+
+        $this->assertSupported($defaultEncoding, false);
         $this->defaultEncoding = $defaultEncoding;
     }
 
     /**
-     * {@inheritdoc}
+     * @param array<string>|string|null $from
      */
-    public function transcode($string, $from = null, $to = null)
+    public function transcode(string $string, $from = null, ?string $to = null): string
     {
         if ($from) {
             if (is_array($from)) {
-                array_map(array($this, 'assertSupported'), $from);
+                array_map([$this, 'assertSupported'], $from);
             } else {
                 $this->assertSupported($from);
             }
+        } else {
+            $from = 'auto';
         }
 
-        if (!$from || 'auto' === $from) {
-            set_error_handler(
-                function ($no, $warning) use ($string) {
-                    throw new UndetectableEncodingException($string, $warning);
-                },
-                E_WARNING
-            );
+        if ($to) {
+            $this->assertSupported($to, false);
         }
 
-
-        if ($to) {
-            $this->assertSupported($to);
+        if ($from === 'auto') {
+            $from = mb_detect_encoding($string, 'auto', true);
         }
-
+
+        if ($from === false) {
+            throw new UndetectableEncodingException($string, 'Unable to detect character encoding');
+        }
+
         $result = mb_convert_encoding(
             $string,
             $to ?: $this->defaultEncoding,
-            $from ?: 'auto'
+            $from
         );
-
-        restore_error_handler();
-
+
         return $result;
     }
-
-    private function assertSupported($encoding)
+
+    /**
+     * @throws UnsupportedEncodingException
+     */
+    private function assertSupported(string $encoding, bool $allowAuto = true): void
     {
-        if (!$this->isSupported($encoding)) {
+        if (!$this->isSupported($encoding, $allowAuto)) {
             throw new UnsupportedEncodingException($encoding);
         }
     }
-    
-    private function isSupported($encoding)
+
+    private function isSupported(string $encoding, bool $allowAuto): bool
     {
-        return isset(self::$encodings[strtolower($encoding)]);
+        return ($allowAuto && $encoding === 'auto') || isset(self::$encodings[strtolower($encoding)]);
     }
 }
diff --git a/src/Transcoder.php b/src/Transcoder.php
@@ -1,28 +1,33 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder;
 
 use Ddeboer\Transcoder\Exception\ExtensionMissingException;
 use Ddeboer\Transcoder\Exception\UnsupportedEncodingException;
 
 class Transcoder implements TranscoderInterface
 {
-    private static $chain;
-
+    /**
+     * @var array<string, TranscoderInterface>
+     */
+    private static array $chain;
+
     /**
      * @var TranscoderInterface[]
      */
-    private $transcoders = [];
-
+    private array $transcoders = [];
+
+    /**
+     * @param TranscoderInterface[] $transcoders
+     */
     public function __construct(array $transcoders)
     {
         $this->transcoders = $transcoders;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function transcode($string, $from = null, $to = null)
+    public function transcode(string $string, ?string $from = null, ?string $to = null): string
     {
         foreach ($this->transcoders as $transcoder) {
             try {
@@ -31,27 +36,27 @@ public function transcode($string, $from = null, $to = null)
                 // Ignore as long as the fallback transcoder is all right
             }
         }
-
+
+        if (!isset($e)) {
+            throw new UnsupportedEncodingException('of any kind', 'No transcoder provided.');
+        }
+
         throw $e;
     }
 
     /**
-     * Create a transcoder
-     * 
-     * @param string $defaultEncoding
-     *
-     * @return TranscoderInterface
+     * Create a transcoder.
      *
      * @throws ExtensionMissingException
      */
-    public static function create($defaultEncoding = 'UTF-8')
+    public static function create(string $defaultEncoding = 'UTF-8'): TranscoderInterface
     {
         if (isset(self::$chain[$defaultEncoding])) {
             return self::$chain[$defaultEncoding];
         }
-        
+
         $transcoders = [];
-        
+
         try {
             $transcoders[] = new MbTranscoder($defaultEncoding);
         } catch (ExtensionMissingException $mb) {
@@ -61,10 +66,14 @@ public static function create($defaultEncoding = 'UTF-8')
         try {
             $transcoders[] = new IconvTranscoder($defaultEncoding);
         } catch (ExtensionMissingException $iconv) {
-            // Neither mbstring nor iconv
-            throw $iconv;
+            // Ignore missing iconv extension; hopefully, we have mbstring.
+        }
+
+        // Neither mbstring nor iconv
+        if (count($transcoders) === 0) {
+            throw new ExtensionMissingException('mbstring or iconv');
         }
-        
+
         self::$chain[$defaultEncoding] = new self($transcoders);
 
         return self::$chain[$defaultEncoding];

diff --git a/src/TranscoderInterface.php b/src/TranscoderInterface.php
@@ -1,21 +1,20 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder;
 
 use Ddeboer\Transcoder\Exception\UnsupportedEncodingException;
 
 interface TranscoderInterface
 {
     /**
-     * Transcode a string from one into another encoding
+     * Transcode a string from one encoding into another.
      *
-     * @param string $string String
-     * @param string $from   From encoding (optional)
-     * @param string $to     To encoding (optional)
+     * @param string $from Source encoding (optional)
+     * @param string $to Target encoding (optional)
      *
-     * @return string
-     * 
      * @throws UnsupportedEncodingException
      */
-    public function transcode($string, $from = null, $to = null);
+    public function transcode(string $string, ?string $from = null, ?string $to = null): string;
 }
diff --git a/tests/IconvTranscoderTest.php b/tests/IconvTranscoderTest.php
@@ -1,56 +1,58 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Tests;
 
 use Ddeboer\Transcoder\IconvTranscoder;
 
-class IconvTranscoderTest extends \PHPUnit_Framework_TestCase
+class IconvTranscoderTest extends \PHPUnit\Framework\TestCase
 {
+    private IconvTranscoder $transcoder;
+
     /**
-     * @var IconvTranscoder
+     * @before
      */
-    private $transcoder;
-
-    protected function setUp()
+    protected function doSetUp(): void
     {
         $this->transcoder = new IconvTranscoder();
+        // Passing null (empty encoding name) to iconv makes it detect encoding from locale.
+        // The phpunit-bridge sets locale to C for consistency but that implies ASCII.
+        // This file uses UTF-8 so we have to set the locale accordingly.
+        $this->setLocale(\LC_ALL, 'C.UTF-8');
     }
-
-    /**
-     * @expectedException \Ddeboer\Transcoder\Exception\UnsupportedEncodingException
-     * @expectedExceptionMessage bad-encoding
-     */
-    public function testTranscodeUnsupportedFromEncoding()
+
+    public function testTranscodeUnsupportedFromEncoding(): void
     {
+        $this->expectException(\Ddeboer\Transcoder\Exception\UnsupportedEncodingException::class);
+        $this->expectExceptionMessage('bad-encoding');
         $this->transcoder->transcode('bla', 'bad-encoding');
     }
-    
-    public function testDetectEncoding()
+
+    public function testDetectEncoding(): void
     {
-        $this->transcoder->transcode('España', null, 'iso-8859-1');
+        $isoLatin1 = $this->transcoder->transcode('España', null, 'iso-8859-1');
+        $this->assertEquals($isoLatin1, "Espa\xf1a");
     }
 
-    /**
-     * @expectedException \Ddeboer\Transcoder\Exception\IllegalCharacterException
-     */
-    public function testTranscodeIllegalCharacter()
+    public function testTranscodeIllegalCharacter(): void
     {
-        $this->transcoder->transcode('“', null, 'iso-8859-1');
+        $this->expectException(\Ddeboer\Transcoder\Exception\IllegalCharacterException::class);
+        $this->transcoder->transcode('“', 'utf-8', 'iso-8859-1');
     }
 
     /**
      * @dataProvider getStrings
      */
-    public function testTranscode($string, $encoding)
+    public function testTranscode(string $string, string $encoding): void
     {
-        $result = $this->transcoder->transcode($string, null, $encoding);
+        $result = $this->transcoder->transcode($string, 'utf-8', $encoding);
         $this->assertEquals($string, $this->transcoder->transcode($result, $encoding));
     }
-
-    public function getStrings()
+
+    /** @return iterable<array{string, string}> */
+    public function getStrings(): iterable
     {
-        return [
-            ['España', 'iso-8859-1']
-        ];
+        yield ['España', 'iso-8859-1'];
     }
 }
diff --git a/tests/MbTranscoderTest.php b/tests/MbTranscoderTest.php
@@ -1,53 +1,58 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Tests;
 
 use Ddeboer\Transcoder\MbTranscoder;
 
-class MbTranscoderTest extends \PHPUnit_Framework_TestCase
+class MbTranscoderTest extends \PHPUnit\Framework\TestCase
 {
+    private MbTranscoder $transcoder;
+
     /**
-     * @var MbTranscoder
+     * @before
      */
-    private $transcoder;
-
-    protected function setUp()
+    protected function doSetUp(): void
     {
         $this->transcoder = new MbTranscoder();
     }
 
-    /**
-     * @expectedException \Ddeboer\Transcoder\Exception\UnsupportedEncodingException
-     * @expectedExceptionMessage bad-encoding
-     */
-    public function testTranscodeUnsupportedFromEncoding()
+    public function testTranscodeUnsupportedFromEncoding(): void
     {
+        $this->expectException(\Ddeboer\Transcoder\Exception\UnsupportedEncodingException::class);
+        $this->expectExceptionMessage('bad-encoding');
         $this->transcoder->transcode('bla', 'bad-encoding');
     }
 
-    /**
-     * @expectedException \Ddeboer\Transcoder\Exception\UnsupportedEncodingException
-     * @expectedExceptionMessage bad-encoding
-     */
-    public function testTranscodeUnsupportedToEncoding()
+    public function testTranscodeUnsupportedToEncoding(): void
     {
-        $this->transcoder->transcode('bla', null, 'bad-encoding');
+        $this->expectException(\Ddeboer\Transcoder\Exception\UnsupportedEncodingException::class);
+        $this->expectExceptionMessage('bad-encoding');
+        $this->transcoder->transcode('bla', 'utf-8', 'bad-encoding');
     }
-    
-    public function testDetectEncoding()
+
+    public function testDetectEncoding(): void
     {
-        $result = $this->transcoder->transcode('España', null, 'iso-8859-1');
-        $this->transcoder->transcode($result);
+        $oldLanguage = ini_get('mbstring.language');
+        assert($oldLanguage !== false);
+        ini_set('mbstring.language', 'ru');
+
+        $utf8 = 'пирожки';
+        $this->assertEquals($utf8, $this->transcoder->transcode($utf8));
+
+        $koi8r = $this->transcoder->transcode($utf8, 'utf-8', 'koi8-r');
+        $this->assertEquals($utf8, $this->transcoder->transcode($koi8r));
+
+        ini_set('mbstring.language', $oldLanguage);
     }
-
-    /**
-     * @expectedException \Ddeboer\Transcoder\Exception\UndetectableEncodingException
-     * @expectedExceptionMessage is undetectable 
-     */
-    public function testUndetectableEncoding()
+
+    public function testUndetectableEncoding(): void
     {
+        $this->expectException(\Ddeboer\Transcoder\Exception\UndetectableEncodingException::class);
+        $this->expectExceptionMessage('is undetectable');
         $result = $this->transcoder->transcode(
-            '‘curly quotes make this incompatible with 1252’',
+            '‘Windows-1252 encodes curly quotes as 0x91 and 0x92, which are indistinguishable from any other single-byte encoding’',
             null,
             'windows-1252'
         );
@@ -57,17 +62,16 @@ public function testUndetectableEncoding()
     /**
      * @dataProvider getStrings
      */
-    public function testTranscode($string, $encoding)
+    public function testTranscode(string $string, string $encoding): void
     {
         $result = $this->transcoder->transcode($string, null, $encoding);
         $this->assertEquals($string, $this->transcoder->transcode($result, $encoding));
     }
-
-    public function getStrings()
+
+    /** @return iterable<array{string, string}> */
+    public function getStrings(): iterable
     {
-        return [
-            ['‘España’', 'windows-1252'],
-            ['España', 'iso-8859-1']
-        ];
+        yield ['‘España’', 'windows-1252'];
+        yield ['España', 'iso-8859-1'];
     }
 }
diff --git a/tests/TranscoderTest.php b/tests/TranscoderTest.php
@@ -1,35 +1,37 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Ddeboer\Transcoder\Tests;
 
 use Ddeboer\Transcoder\Transcoder;
+use Ddeboer\Transcoder\TranscoderInterface;
 
-class TranscoderTest extends \PHPUnit_Framework_TestCase
+class TranscoderTest extends \PHPUnit\Framework\TestCase
 {
+    private TranscoderInterface $transcoder;
+
     /**
-     * @var Transcoder
+     * @before
      */
-    private $transcoder;
-
-    protected function setUp()
+    protected function doSetUp(): void
     {
         $this->transcoder = Transcoder::create();
     }
 
     /**
      * @dataProvider getStrings
      */
-    public function testTranscode($string, $encoding)
+    public function testTranscode(string $string, string $encoding): void
     {
         $result = $this->transcoder->transcode($string, 'UTF-8', $encoding);
         $this->assertEquals($string, $this->transcoder->transcode($result, $encoding));
     }
-
-    public function getStrings()
+
+    /** @return iterable<array{string, string}> */
+    public function getStrings(): iterable
     {
-        return [
-            ['España', 'UTF-8'],
-            ['bla', 'windows-1257'] // Encoding only supported by iconv
-        ];
+        yield ['España', 'UTF-8'];
+        yield ['bla', 'windows-1257']; // Encoding only supported by iconv
     }
 }