Enhancement: Implement IndentNormalizer

README.md

@@ -15,6 +15,37 @@ Run
 $ composer require localheinz/json-normalizer
 ```
 
+## Usage
+
+This package comes with the following normalizers:
+
+* [`Localheinz\Json\Normalizer\IndentNormalizer`](#IndentNormalizer)
+
+:bulb: All of these normalizers implement the `Localheinz\Json\Normalizer\NormalizerInterface`. 
+
+### `IndentNormalizer`
+
+If you need to adjust the indentation of a JSON file, you can use the `IndentNormalizer`.
+
+```php
+use Localheinz\Json\Normalizer;
+
+$json = <<<'JSON'
+{
+    "name": "Andreas Möller",
+    "url": "https://localheinz.com"
+}
+JSON;
+
+$indent = '  ';
+
+$normalizer = new Normalizer\IndentNormalizer($indent);
+
+$normalized = $normalizer->normalize($json);
+```
+
+The normalized version will now be indented with 2 spaces.
+
 ## Contributing
 
 Please have a look at [`CONTRIBUTING.md`](.github/CONTRIBUTING.md).

src/IndentNormalizer.php

@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2018 Andreas Möller.
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ *
+ * @see https://github.com/localheinz/json-normalizer
+ */
+
+namespace Localheinz\Json\Normalizer;
+
+use Localheinz\Json\Printer\Printer;
+use Localheinz\Json\Printer\PrinterInterface;
+
+final class IndentNormalizer implements NormalizerInterface
+{
+    /**
+     * @var string
+     */
+    private $indent;
+
+    /**
+     * @var PrinterInterface
+     */
+    private $printer;
+
+    /**
+     * @param string                $indent
+     * @param null|PrinterInterface $printer
+     *
+     * @throws \InvalidArgumentException
+     */
+    public function __construct(string $indent, PrinterInterface $printer = null)
+    {
+        if (1 !== \preg_match('/^[ \t]+$/', $indent)) {
+            throw new \InvalidArgumentException(\sprintf(
+                '"%s" is not a valid indent.',
+                $indent
+            ));
+        }
+
+        $this->indent = $indent;
+
+        $this->printer = $printer ?: new Printer();
+    }
+
+    public function normalize(string $json): string
+    {
+        if (null === \json_decode($json) && JSON_ERROR_NONE !== \json_last_error()) {
+            throw new \InvalidArgumentException(\sprintf(
+                '"%s" is not valid JSON.',
+                $json
+            ));
+        }
+
+        return $this->printer->print(
+            $json,
+            $this->indent
+        );
+    }
+}

src/NormalizerInterface.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2018 Andreas Möller.
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ *
+ * @see https://github.com/localheinz/json-normalizer
+ */
+
+namespace Localheinz\Json\Normalizer;
+
+interface NormalizerInterface
+{
+    /**
+     * @param string $json
+     *
+     * @throws \InvalidArgumentException
+     * @throws \RuntimeException
+     *
+     * @return string
+     */
+    public function normalize(string $json): string;
+}

test/Unit/IndentNormalizerTest.php

@@ -0,0 +1,120 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2018 Andreas Möller.
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ *
+ * @see https://github.com/localheinz/json-normalizer
+ */
+
+namespace Localheinz\Json\Normalizer\Test\Unit;
+
+use Localheinz\Json\Normalizer\IndentNormalizer;
+use Localheinz\Json\Normalizer\NormalizerInterface;
+use Localheinz\Json\Printer\PrinterInterface;
+use Localheinz\Test\Util\Helper;
+use PHPUnit\Framework;
+use Prophecy\Argument;
+
+final class IndentNormalizerTest extends Framework\TestCase
+{
+    use Helper;
+
+    public function testImplementsNormalizerInterface()
+    {
+        $this->assertClassImplementsInterface(NormalizerInterface::class, IndentNormalizer::class);
+    }
+
+    public function testNormalizeRejectsInvalidJson()
+    {
+        $indent = '  ';
+
+        $json = $this->faker()->realText();
+
+        $normalizer = new IndentNormalizer(
+            $indent,
+            $this->prophesize(PrinterInterface::class)->reveal()
+        );
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage(\sprintf(
+            '"%s" is not valid JSON.',
+            $json
+        ));
+
+        $normalizer->normalize($json);
+    }
+
+    /**
+     * @dataProvider providerInvalidIndent
+     *
+     * @param string $indent
+     */
+    public function testConstructorRejectsInvalidIndent(string $indent)
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage(\sprintf(
+            '"%s" is not a valid indent.',
+            $indent
+        ));
+
+        new IndentNormalizer(
+            $indent,
+            $this->prophesize(PrinterInterface::class)->reveal()
+        );
+    }
+
+    public function providerInvalidIndent(): \Generator
+    {
+        $values = [
+            'not-whitespace' => $this->faker()->sentence,
+            'contains-line-feed' => " \n ",
+        ];
+
+        foreach ($values as $key => $value) {
+            yield $key => [
+                $value,
+            ];
+        }
+    }
+
+    public function testNormalizeUsesPrinterToNormalizeJsonWithIndent()
+    {
+        $indent = '  ';
+
+        $json = <<<'JSON'
+{
+    "name": "Andreas Möller",
+    "url": "https://localheinz.com"
+}
+JSON;
+
+        $normalized = <<<'JSON'
+{
+    "name": "Andreas Möller (normalized)",
+    "url": "https://localheinz.com"
+}
+JSON;
+
+        $printer = $this->prophesize(PrinterInterface::class);
+
+        $printer
+            ->print(
+                Argument::is($json),
+                Argument::is($indent)
+            )
+            ->shouldBeCalled()
+            ->willReturn($normalized);
+
+        $normalizer = new IndentNormalizer(
+            $indent,
+            $printer->reveal()
+        );
+
+        $this->assertSame($normalized, $normalizer->normalize($json));
+    }
+}