Enhancement: Implement ValueGenerator

CHANGELOG.md

@@ -8,4 +8,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 For a full diff see [`f4208b3...main`][f4208b3...main].
 
+### Added
+
+- Added `ValueGenerator` ([#1]), by [@localheinz]
+
 [f4208b3...main]: https://github.com/ergebnis/data-generator/compare/f4208b3...main
+
+[#1]: https://github.com/ergebnis/data-generator/pull/1
+
+[@localheinz]: https://github.com/localheinz

README.md

@@ -24,7 +24,35 @@ composer require ergebnis/data-generator
 
 ## Usage
 
-💡 This is a great place for showing a few usage examples!
+This project comes with the following data generators:
+
+- [`Ergebnis\DataGenerator\ValueGenerator`](#valuegenerator)
+
+### `ValueGenerator`
+
+#### Generate one or more values from a known list of `string` values
+
+```php
+<?php
+
+declare(strict_types=1);
+
+use Ergebnis\DataGenerator;
+
+$generator = new DataGenerator\ValueGenerator(
+    'foo',
+    'bar',
+    'baz',
+);
+
+foreach ($generator->generate() as $value) {
+    echo $value . PHP_EOL
+}
+
+// foo
+// bar
+// baz
+```
 
 ## Changelog
 

src/Exception/InvalidValuesException.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2017-2023 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/data-generator
+ */
+
+namespace Ergebnis\DataGenerator\Exception;
+
+final class InvalidValuesException extends \InvalidArgumentException
+{
+    public static function empty(): self
+    {
+        return new self('Values can not be empty.');
+    }
+}

src/Example.php → src/StringGenerator.php

@@ -13,19 +13,10 @@
 
 namespace Ergebnis\DataGenerator;
 
-final class Example
+interface StringGenerator
 {
-    private function __construct(private readonly string $value)
-    {
-    }
-
-    public static function fromString(string $value): self
-    {
-        return new self($value);
-    }
-
-    public function toString(): string
-    {
-        return $this->value;
-    }
+    /**
+     * @return \Generator<string>
+     */
+    public function generate(): \Generator;
 }

src/ValueGenerator.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2017-2023 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/data-generator
+ */
+
+namespace Ergebnis\DataGenerator;
+
+final class ValueGenerator implements StringGenerator
+{
+    /**
+     * @var array<string>
+     */
+    private readonly array $values;
+
+    /**
+     * @throws Exception\InvalidValuesException
+     */
+    public function __construct(string ...$values)
+    {
+        if (0 === \count($values)) {
+            throw Exception\InvalidValuesException::empty();
+        }
+
+        $this->values = $values;
+    }
+
+    public function generate(): \Generator
+    {
+        foreach ($this->values as $value) {
+            yield $value;
+        }
+    }
+}

test/Unit/Exception/InvalidValuesExceptionTest.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2017-2023 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/data-generator
+ */
+
+namespace Ergebnis\DataGenerator\Test\Unit\Exception;
+
+use Ergebnis\DataGenerator\Exception;
+use PHPUnit\Framework;
+
+#[Framework\Attributes\CoversClass(Exception\InvalidValuesException::class)]
+final class InvalidValuesExceptionTest extends Framework\TestCase
+{
+    public function testEmptyReturnsException(): void
+    {
+        $exception = Exception\InvalidValuesException::empty();
+
+        $message = 'Values can not be empty.';
+
+        self::assertSame($message, $exception->getMessage());
+    }
+}

test/Unit/ValueGeneratorTest.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright (c) 2017-2023 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/data-generator
+ */
+
+namespace Ergebnis\DataGenerator\Test\Unit;
+
+use Ergebnis\DataGenerator\Exception;
+use Ergebnis\DataGenerator\Test;
+use Ergebnis\DataGenerator\ValueGenerator;
+use PHPUnit\Framework;
+
+#[Framework\Attributes\CoversClass(ValueGenerator::class)]
+#[Framework\Attributes\UsesClass(Exception\InvalidValuesException::class)]
+final class ValueGeneratorTest extends Framework\TestCase
+{
+    use Test\Util\Helper;
+
+    public function testConstructorRejectsEmptyValues(): void
+    {
+        $this->expectException(Exception\InvalidValuesException::class);
+
+        new ValueGenerator();
+    }
+
+    public function testGenerateReturnsGeneratorThatYieldsValues(): void
+    {
+        /** @var list<string> $values */
+        $values = self::faker()->words();
+
+        $generator = new ValueGenerator(...$values);
+
+        $generated = \iterator_to_array($generator->generate());
+
+        self::assertSame($values, $generated);
+    }
+}