Enhancement: Implement ConcatenatingValueGenerator

CHANGELOG.md

@@ -12,10 +12,12 @@ For a full diff see [`f4208b3...main`][f4208b3...main].
 
 - Added `ValueGenerator` ([#1]), by [@localheinz]
 - Added `OptionalValueGenerator` ([#2]), by [@localheinz]
+- Added `ConcatenatingValueGenerator` ([#3]), by [@localheinz]
 
 [f4208b3...main]: https://github.com/ergebnis/data-generator/compare/f4208b3...main
 
 [#1]: https://github.com/ergebnis/data-generator/pull/1
 [#2]: https://github.com/ergebnis/data-generator/pull/2
+[#3]: https://github.com/ergebnis/data-generator/pull/3
 
 [@localheinz]: https://github.com/localheinz

README.md

@@ -26,9 +26,46 @@ composer require ergebnis/data-generator
 
 This project comes with the following data generators:
 
+- [`Ergebnis\DataGenerator\ConcatenatingValueGenerator`](#ConcatenatingValuegenerator)
 - [`Ergebnis\DataGenerator\OptionalValueGenerator`](#optionalvaluegenerator)
 - [`Ergebnis\DataGenerator\ValueGenerator`](#valuegenerator)
 
+### `ConcatenatingValueGenerator`
+
+Use the `ConcatenatingValueGenerator` to generate values by concatenating values generated from one or more `StringGenerator`s:
+
+```php
+<?php
+
+declare(strict_types=1);
+
+use Ergebnis\DataGenerator;
+
+$generator = new DataGenerator\ConcatenatingValueGenerator(
+    new DataGenerator\ValueGenerator(
+        'foo',
+        'bar',
+        'baz',
+    ),
+    new DataGenerator\ValueGenerator('-'),
+    new DataGenerator\ValueGenerator(
+        'qux',
+        'quux',
+    ),
+);
+
+foreach ($generator->generate() as $value) {
+    echo $value . PHP_EOL
+}
+
+// foo-qux
+// foo-quux
+// bar-qux
+// bar-quux
+// baz-qux
+// baz-quux
+```
+
 ### `OptionalValueGenerator`
 
 Use the `OptionalValueGenerator` to generate an empty string and one or more values from a list of `string` values:

psalm-baseline.xml

@@ -1,5 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <files psalm-version="5.18.0@b113f3ed0259fd6e212d87c3df80eec95a6abf19">
+  <file src="src/ConcatenatingValueGenerator.php">
+    <PropertyNotSetInConstructor>
+      <code>$secondGenerator</code>
+    </PropertyNotSetInConstructor>
+  </file>
+  <file src="test/Unit/ConcatenatingValueGeneratorTest.php">
+    <MixedArgument>
+      <code>$values</code>
+    </MixedArgument>
+  </file>
   <file src="test/Unit/OptionalValueGeneratorTest.php">
     <MixedArgument>
       <code>$values</code>

src/ConcatenatingValueGenerator.php

@@ -0,0 +1,59 @@
+<?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 ConcatenatingValueGenerator implements StringGenerator
+{
+    private readonly StringGenerator $firstGenerator;
+    private readonly StringGenerator $secondGenerator;
+
+    /**
+     * @throws \InvalidArgumentException
+     */
+    public function __construct(StringGenerator ...$stringGenerators)
+    {
+        $count = \count($stringGenerators);
+
+        if (0 === $count) {
+            throw new \InvalidArgumentException('Need at least one generator');
+        }
+
+        $this->firstGenerator = \array_shift($stringGenerators);
+
+        if (1 === $count) {
+            $this->secondGenerator = new ValueGenerator('');
+
+            return;
+        }
+
+        if (2 === $count) {
+            $this->secondGenerator = \array_shift($stringGenerators);
+
+            return;
+        }
+
+        if (2 < $count) {
+            $this->secondGenerator = new self(...$stringGenerators);
+        }
+    }
+
+    public function generate(): \Generator
+    {
+        foreach ($this->firstGenerator->generate() as $firstValue) {
+            foreach ($this->secondGenerator->generate() as $secondValue) {
+                yield $firstValue . $secondValue;
+            }
+        }
+    }
+}

test/Unit/ConcatenatingValueGeneratorTest.php

@@ -0,0 +1,93 @@
+<?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
+ */
+
+use Ergebnis\DataGenerator\ConcatenatingValueGenerator;
+use Ergebnis\DataGenerator\Test;
+use Ergebnis\DataGenerator\ValueGenerator;
+use PHPUnit\Framework;
+
+#[Framework\Attributes\CoversClass(ConcatenatingValueGenerator::class)]
+#[Framework\Attributes\UsesClass(ValueGenerator::class)]
+final class ConcatenatingValueGeneratorTest extends Framework\TestCase
+{
+    use Test\Util\Helper;
+
+    public function testGenerateReturnsGeneratorThatYieldsValuesFromSingleStringGenerator(): void
+    {
+        $values = self::faker()->words();
+
+        $generator = new ConcatenatingValueGenerator(new ValueGenerator(...$values));
+
+        $generated = \iterator_to_array($generator->generate());
+
+        self::assertSame($values, $generated);
+    }
+
+    public function testGenerateReturnsGeneratorThatYieldsValuesFromTwoStringGenerators(): void
+    {
+        $generator = new ConcatenatingValueGenerator(
+            new ValueGenerator(
+                'foo',
+                'bar',
+            ),
+            new ValueGenerator(
+                '1',
+                '2',
+                '3',
+            ),
+        );
+
+        $generated = \iterator_to_array($generator->generate());
+
+        $expected = [
+            'foo1',
+            'foo2',
+            'foo3',
+            'bar1',
+            'bar2',
+            'bar3',
+        ];
+
+        self::assertSame($expected, $generated);
+    }
+
+    public function testGenerateReturnsGeneratorThatYieldsValuesFromThreeStringGenerators(): void
+    {
+        $generator = new ConcatenatingValueGenerator(
+            new ValueGenerator(
+                'foo',
+                'bar',
+                'baz',
+            ),
+            new ValueGenerator('-'),
+            new ValueGenerator(
+                'qux',
+                'quux',
+            ),
+        );
+
+        $generated = \iterator_to_array($generator->generate());
+
+        $expected = [
+            'foo-qux',
+            'foo-quux',
+
+            'bar-qux',
+            'bar-quux',
+            'baz-qux',
+            'baz-quux',
+        ];
+
+        self::assertSame($expected, $generated);
+    }
+}