Convert tests to Pest

- Force PHP 8.4

.gitignore

@@ -1,3 +1,3 @@
 .idea
 vendor
-*.tests.txt
+*-tests.txt

README.md

@@ -2,6 +2,8 @@
 
 This project contains PHP utility classes whose functionality is inspired by their F# counterparts.
 
+The v2 series requires at least PHP 8.4. A similar API exists for PHP 8.2 - 8.3 in version 1 of this project; see its README for specifics.
+
 ## What It Provides
 
 This early-stage library currently provides two classes, both of which are designed to wrap values and indicate the state of the action that produced them. `Option<T>` represents a variable that may or may not have a value. `Result<TOK, TError>` represents the result of an action; the "ok" and "error" states both provide a value.
@@ -11,12 +13,12 @@ This early-stage library currently provides two classes, both of which are desig
 | **Creating**                                      | `::Some(T)` for Some                                  | `::OK(TOK)` for OK                                                          |
 |                                                   | `::None()` for None                                   | `::Error(TError)` for Error                                                 |
 |                                                   | `::of($value)` _None if `null`_                       |                                                                             |
-| **Querying**                                      | `->isSome(): bool`                                    | `->isOK(): bool`                                                            |
-|                                                   | `->isNone(): bool`                                    | `->isError(): bool`                                                         |
+| **Querying**                                      | `->isSome: bool`                                      | `->isOK: bool`                                                              |
+|                                                   | `->isNone: bool`                                      | `->isError: bool`                                                           |
 |                                                   | `->contains(T, $strict = true): bool`                 | `->contains(TOK, $strict = true): bool`                                     |
 |                                                   | `->exists(callable(T): bool): bool`                   | `->exists(callable(TOK): bool): bool`                                       |
-| **Reading**<br>                                   | `->get(): T`                                          | `->getOK(): TOK`                                                            |
-| _all throw if called on missing value_            |                                                       | `->getError(): TError`                                                      |
+| **Reading**<br>                                   | `->value: T`                                          | `->ok: TOK`                                                                 |
+| _all throw if called on missing value_            |                                                       | `->error: TError`                                                           |
 | **Transforming**<br>                              | `->map(callable(T): TMapped): Option<TMapped>`        | `->map(callable(TOK): TMapped): Result<TMapped, TError>`                    |
 | _all still `Option` or `Result`_                  |                                                       | `->mapError(callable(TError): TMapped): Result<TOK, TMapped>`               |
 | **Iterating**                                     | `->iter(callable(T): void): void`                     | `->iter(callable(TOK): void): void`                                         |

composer.json

@@ -17,11 +17,11 @@
     "rss": "https://git.bitbadger.solutions/bit-badger/inspired-by-fsharp.rss"
   },
   "require": {
-    "php": "8.2 - 8.3"
+    "php": ">=8.4"
   },
   "require-dev": {
-    "phpunit/phpunit": "^11",
-    "phpoption/phpoption": "^1"
+    "phpoption/phpoption": "^1",
+    "pestphp/pest": "^3.5"
   },
   "autoload": {
     "psr-4": {
@@ -30,10 +30,15 @@
   },
   "autoload-dev": {
     "psr-4": {
-      "Test\\": "./tests"
+      "Tests\\": "./tests"
     }
   },
   "archive": {
     "exclude": [ "/tests", "/.gitattributes", "/.gitignore", "/.git", "/composer.lock" ]
+  },
+  "config": {
+    "allow-plugins": {
+      "pestphp/pest-plugin": true
+    }
   }
 }

phpunit.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.3/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+>
+    <testsuites>
+        <testsuite name="Test Suite">
+            <directory suffix="Test.php">./tests</directory>
+        </testsuite>
+    </testsuites>
+    <source>
+        <include>
+            <directory suffix=".php">./src</directory>
+        </include>
+    </source>
+</phpunit>

src/Option.php

@@ -25,50 +25,38 @@ use InvalidArgumentException;
  *
  * @template T The type of value represented by this option
  */
-readonly class Option
+class Option
 {
     /** @var T|null $value The value for this option  */
-    private mixed $value;
+    private mixed $val;
 
     /**
      * @param T|null $value The possibly null value for this option
      */
     private function __construct(mixed $value = null)
     {
-        $this->value = $value;
+        $this->val = $value;
     }
 
     /**
-     * Get the value of this option
-     *
-     * @return T The value of the option
+     * @var T The value of this option (read-only)
+     * @throws InvalidArgumentException If called on a `None` option
      */
-    public function get(): mixed
-    {
-        return match (true) {
-            $this->isSome() => $this->value,
-            default         => throw new InvalidArgumentException('Cannot get the value of a None option'),
+    public mixed $value {
+        get => match ($this->val) {
+            null    => throw new InvalidArgumentException('Cannot get the value of a None option'),
+            default => $this->val,
         };
     }
 
-    /**
-     * Does this option have a `None` value?
-     *
-     * @return bool True if the option is `None`, false if it is `Some`
-     */
-    public function isNone(): bool
-    {
-        return is_null($this->value);
+    /** @var bool True if the option is `None`, false if it is `Some` */
+    public bool $isNone {
+        get => is_null($this->val);
     }
 
-    /**
-     * Does this option have a `Some` value?
-     *
-     * @return bool True if the option is `Some`, false if it is `None`
-     */
-    public function isSome(): bool
-    {
-        return !$this->isNone();
+    /** @var bool True if the option is `Some`, false if it is `None` */
+    public bool $isSome{
+        get => !$this->isNone;
     }
 
     /**
@@ -79,7 +67,7 @@ readonly class Option
      */
     public function getOrDefault(mixed $default): mixed
     {
-        return $this->value ?? $default;
+        return $this->val ?? $default;
     }
 
     /**
@@ -91,18 +79,19 @@ readonly class Option
      */
     public function getOrCall(callable $f): mixed
     {
-        return $this->value ?? $f();
+        return $this->val ?? $f();
     }
 
     /**
-     * Get the value, or throw the
+     * Get the value, or throw the exception using the given function
+     *
      * @param callable(): Exception $exFunc A function to construct the exception to throw
      * @return T The value of the option if `Some`
      * @throws Exception If the option is `None`
      */
     public function getOrThrow(callable $exFunc): mixed
     {
-        return $this->value ?? throw $exFunc();
+        return $this->val ?? throw $exFunc();
     }
 
     /**
@@ -117,7 +106,7 @@ readonly class Option
      */
     public function bind(callable $f): Option
     {
-        return $this->isNone() ? $this : $f($this->get());
+        return $this->isNone ? $this : $f($this->val);
     }
 
     /**
@@ -130,8 +119,8 @@ readonly class Option
     public function contains(mixed $value, bool $strict = true): bool
     {
         return match (true) {
-            $this->isNone() => false,
-            default         => $strict ? $this->value === $value : $this->value == $value,
+            $this->isNone => false,
+            default       => $strict ? $this->val === $value : $this->val == $value,
         };
     }
 
@@ -143,7 +132,7 @@ readonly class Option
      */
     public function exists(callable $f): bool
     {
-        return $this->isSome() ? $f($this->value) : false;
+        return $this->isSome ? $f($this->val) : false;
     }
 
     /**
@@ -155,7 +144,7 @@ readonly class Option
      */
     public function map(callable $f): self
     {
-        return $this->isSome() ? self::Some($f($this->get())) : $this;
+        return $this->isSome ? self::Some($f($this->val)) : $this;
     }
 
     /**
@@ -165,8 +154,8 @@ readonly class Option
      */
     public function iter(callable $f): void
     {
-        if ($this->isSome()) {
-            $f($this->value);
+        if ($this->isSome) {
+            $f($this->val);
         }
     }
 
@@ -178,7 +167,7 @@ readonly class Option
      */
     public function filter(callable $f): self
     {
-        return $this->isNone() || $this->exists($f) ? $this : self::None();
+        return $this->isNone || $this->exists($f) ? $this : self::None();
     }
 
     /**
@@ -188,7 +177,7 @@ readonly class Option
      */
     public function unwrap(): mixed
     {
-        return $this->value;
+        return $this->val;
     }
 
     /**
@@ -210,7 +199,7 @@ readonly class Option
      */
     public function toArray(): array
     {
-        return $this->isSome() ? [$this->value] : [];
+        return $this->isSome ? [$this->val] : [];
     }
 
     /**
@@ -221,8 +210,8 @@ readonly class Option
     public function toPhpOption(): mixed
     {
         return match (true) {
-            $this->isNone() && class_exists('PhpOption\None') => call_user_func('PhpOption\None::create'),
-            class_exists('PhpOption\Some') => call_user_func('PhpOption\Some::create', $this->value),
+            $this->isNone && class_exists('PhpOption\None') => call_user_func('PhpOption\None::create'),
+            class_exists('PhpOption\Some') => call_user_func('PhpOption\Some::create', $this->val),
             default => throw new Error('PhpOption types could not be found'),
         };
     }
@@ -261,7 +250,7 @@ readonly class Option
     {
         return match (true) {
             is_object($value) && is_a($value, 'PhpOption\Option') =>
-            $value->isDefined() ? self::Some($value->get()) : self::None(),
+                $value->isDefined() ? self::Some($value->get()) : self::None(),
             default                     => new self($value),
         };
     }

src/Result.php

@@ -25,7 +25,7 @@ use InvalidArgumentException;
  * @template TOK The type of the OK result
  * @template TError The type of the error result
  */
-readonly class Result
+class Result
 {
     /** @var Option<TOK> The OK value for this result */
     private Option $okValue;
@@ -45,46 +45,24 @@ readonly class Result
         $this->errorValue = Option::of($errorValue);
     }
 
-    /**
-     * Get the value for an `OK` result
-     *
-     * @return TOK The OK value for this result
-     * @throws InvalidArgumentException If the result is an `Error` result
-     */
-    public function getOK(): mixed
-    {
-        return $this->okValue->get();
+    /** @var TOK The OK value (will throw if result is not OK) */
+    public mixed $ok {
+        get => $this->okValue->value;
     }
 
-    /**
-     * Get the value for an `Error` result
-     *
-     * @return TError The error value for this result
-     * @throws InvalidArgumentException If the result is an `OK` result
-     */
-    public function getError(): mixed
-    {
-        return $this->errorValue->get();
+    /** @var TError The error value (will throw if result is not Error) */
+    public mixed $error {
+        get => $this->errorValue->value;
     }
 
-    /**
-     * Is this result `OK`?
-     *
-     * @return bool True if the result is `OK`, false if it is `Error`
-     */
-    public function isOK(): bool
-    {
-        return $this->okValue->isSome();
+    /** @var bool True if the result is `OK`, false if it is `Error` */
+    public bool $isOK {
+        get => $this->okValue->isSome;
     }
 
-    /**
-     * Is this result `Error`?
-     *
-     * @return bool True if the result is `Error`, false if it is `OK`
-     */
-    public function isError(): bool
-    {
-        return $this->errorValue->isSome();
+    /** @var bool True if the result is `Error`, false if it is `OK` */
+    public bool $isError {
+        get => $this->errorValue->isSome;
     }
 
     /**
@@ -100,7 +78,7 @@ readonly class Result
      */
     public function bind(callable $f): Result
     {
-        return $this->isError() ? $this : $f($this->getOK());
+        return $this->isError ? $this : $f($this->ok);
     }
 
     /**
@@ -113,8 +91,8 @@ readonly class Result
     public function contains(mixed $value, bool $strict = true): bool
     {
         return match (true) {
-            $this->isError() => false,
-            default          => $this->okValue->contains($value, $strict),
+            $this->isError => false,
+            default        => $this->okValue->contains($value, $strict),
         };
     }
 
@@ -126,7 +104,7 @@ readonly class Result
      */
     public function exists(callable $f): bool
     {
-        return $this->isOK() ? $f($this->okValue->get()) : false;
+        return $this->isOK ? $f($this->ok) : false;
     }
 
     /**
@@ -138,7 +116,7 @@ readonly class Result
      */
     public function map(callable $f): self
     {
-        return $this->isOK() ? self::OK($f($this->getOK())) : $this;
+        return $this->isOK ? self::OK($f($this->ok)) : $this;
     }
 
     /**
@@ -150,7 +128,7 @@ readonly class Result
      */
     public function mapError(callable $f): self
     {
-        return $this->isError() ? self::Error($f($this->getError())) : $this;
+        return $this->isError ? self::Error($f($this->error)) : $this;
     }
 
     /**
@@ -160,8 +138,8 @@ readonly class Result
      */
     public function iter(callable $f): void
     {
-        if ($this->isOK()) {
-            $f($this->getOK());
+        if ($this->isOK) {
+            $f($this->ok);
         }
     }
 
@@ -182,7 +160,7 @@ readonly class Result
      */
     public function toOption(): Option
     {
-        return $this->isOK() ? Option::Some($this->getOK()) : Option::None();
+        return $this->isOK ? Option::Some($this->ok) : Option::None();
     }
 
     /**

tests/OptionTest.php

@@ -1,368 +0,0 @@
-<?php
-/**
- * @author Daniel J. Summers <daniel@bitbadger.solutions>
- * @license MIT
- */
-
-declare(strict_types=1);
-
-namespace Test;
-
-use BadMethodCallException;
-use BitBadger\InspiredByFSharp\Option;
-use InvalidArgumentException;
-use PhpOption\{None, Some};
-use PHPUnit\Framework\Attributes\TestDox;
-use PHPUnit\Framework\TestCase;
-
-/**
- * Unit tests for the Option class
- */
-class OptionTest extends TestCase
-{
-    #[TestDox('Get succeeds for Some')]
-    public function testGetSucceedsForSome(): void
-    {
-        $it = Option::Some(9);
-        $this->assertTrue($it->isSome(), 'The option should have been "Some"');
-        $this->assertEquals(9, $it->get(), 'The value was incorrect');
-    }
-
-    #[TestDox('Get fails for None')]
-    public function testGetFailsForNone(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Option::None()->get();
-    }
-
-    #[TestDox('IsNone succeeds with None')]
-    public function testIsNoneSucceedsWithNone(): void
-    {
-        $this->assertTrue(Option::None()->isNone(), '"None" should return true');
-    }
-
-    #[TestDox('IsNone succeeds with Some')]
-    public function testIsNoneSucceedsWithSome(): void
-    {
-        $this->assertFalse(Option::Some(8)->isNone(), '"Some" should return false');
-    }
-
-    #[TestDox('IsSome succeeds with None')]
-    public function testIsSomeSucceedsWithNone(): void
-    {
-        $this->assertFalse(Option::None()->isSome(), '"None" should return false');
-    }
-
-    #[TestDox('IsSome succeeds with Some')]
-    public function testIsSomeSucceedsWithSome(): void
-    {
-        $this->assertTrue(Option::Some('boo')->isSome(), '"Some" should return true');
-    }
-
-    #[TestDox('GetOrDefault succeeds with None')]
-    public function testGetOrDefaultSucceedsWithNone(): void
-    {
-        $this->assertEquals('yes', Option::None()->getOrDefault('yes'), 'Value should have been default');
-    }
-
-    #[TestDox('GetOrDefault succeeds with Some')]
-    public function testGetOrDefaultSucceedsWithSome(): void
-    {
-        $this->assertEquals('no', Option::Some('no')->getOrDefault('yes'), 'Value should have been from option');
-    }
-
-    #[TestDox('GetOrCall succeeds with None')]
-    public function testGetOrCallSucceedsWithNone(): void
-    {
-        $value = Option::None()->getOrCall(new class { public function __invoke(): string { return 'called'; } });
-        $this->assertEquals('called', $value, 'The value should have been obtained from the callable');
-    }
-
-    #[TestDox('GetOrCall succeeds with Some')]
-    public function testGetOrCallSucceedsWithSome(): void
-    {
-        $value = Option::Some('passed')->getOrCall(
-            new class { public function __invoke(): string { return 'called'; } });
-        $this->assertEquals('passed', $value, 'The value should have been obtained from the option');
-    }
-
-    #[TestDox('GetOrThrow succeeds with Some')]
-    public function testGetOrThrowSucceedsWithSome(): void
-    {
-        $value = Option::Some('no throw')->getOrThrow(fn() => new BadMethodCallException('oops'));
-        $this->assertEquals('no throw', $value, 'The "Some" value should have been returned');
-    }
-
-    #[TestDox('GetOrThrow succeeds with None')]
-    public function testGetOrThrowSucceedsWithNone(): void
-    {
-        $this->expectException(BadMethodCallException::class);
-        Option::None()->getOrThrow(fn() => new BadMethodCallException('oops'));
-    }
-
-    #[TestDox('Bind succeeds with None')]
-    public function testBindSucceedsWithNone(): void
-    {
-        $original = Option::None();
-        $bound    = $original->bind(fn($it) => Option::Some('value'));
-        $this->assertTrue($bound->isNone(), 'The option should have been None');
-        $this->assertSame($original, $bound, 'The same None instance should have been returned');
-    }
-
-    #[TestDox('Bind succeeds with Some and Some')]
-    public function testBindSucceedsWithSomeAndSome(): void
-    {
-        $bound = Option::Some('hello')->bind(fn($it) => Option::Some('goodbye'));
-        $this->assertTrue($bound->isSome(), 'The option should have been Some');
-        $this->assertEquals('goodbye', $bound->get(), 'The bound function was not called');
-    }
-
-    #[TestDox('Bind succeeds with Some and None')]
-    public function testBindSucceedsWithSomeAndNone(): void
-    {
-        $bound = Option::Some('greetings')->bind(fn($it) => Option::None());
-        $this->assertTrue($bound->isNone(), 'The option should have been None');
-    }
-
-    #[TestDox('Contains succeeds with None')]
-    public function testContainsSucceedsWithNone(): void
-    {
-        $this->assertFalse(Option::None()->contains(null), '"None" should always return false');
-    }
-
-    #[TestDox('Contains succeeds with Some when strictly equal')]
-    public function testContainsSucceedsWithSomeWhenStrictlyEqual(): void
-    {
-        $this->assertTrue(Option::Some(3)->contains(3), '"Some" with strict equality should be true');
-    }
-
-    #[TestDox('Contains succeeds with Some when strictly unequal')]
-    public function testContainsSucceedsWithSomeWhenStrictlyUnequal(): void
-    {
-        $this->assertFalse(Option::Some('3')->contains(3), '"Some" with strict equality should be false');
-    }
-
-    #[TestDox('Contains succeeds with Some when loosely equal')]
-    public function testContainsSucceedsWithSomeWhenLooselyEqual(): void
-    {
-        $this->assertTrue(Option::Some('3')->contains(3, strict: false), '"Some" with loose equality should be true');
-    }
-
-    #[TestDox('Contains succeeds with Some when loosely unequal')]
-    public function testContainsSucceedsWithSomeWhenLooselyUnequal(): void
-    {
-        $this->assertFalse(Option::Some('3')->contains(4, strict: false), '"Some" with loose equality should be false');
-    }
-
-    #[TestDox('Exists succeeds with Some when matching')]
-    public function testExistsSucceedsWithSomeWhenMatching(): void
-    {
-        $this->assertTrue(Option::Some(14)->exists(fn($it) => $it < 100), 'Exists should have returned true');
-    }
-
-    #[TestDox('Exists succeeds with Some when not matching')]
-    public function testExistsSucceedsWithSomeWhenNotMatching(): void
-    {
-        $this->assertFalse(Option::Some(14)->exists(fn($it) => $it > 100), 'Exists should have returned false');
-    }
-
-    #[TestDox('Exists succeeds with None')]
-    public function testExistsSucceedsWithNone(): void
-    {
-        $this->assertFalse(Option::None()->exists(fn($it) => true), 'Exists should have returned false');
-    }
-
-    #[TestDox('Map succeeds with None')]
-    public function testMapSucceedsWithNone(): void
-    {
-        $tattle = new class { public bool $called = false; };
-        $none   = Option::None();
-        $mapped = $none->map(function () use ($tattle)
-        {
-            $tattle->called = true;
-            return 'hello';
-        });
-        $this->assertTrue($mapped->isNone(), 'The mapped option should be "None"');
-        $this->assertFalse($tattle->called, 'The mapping function should not have been called');
-        $this->assertSame($none, $mapped, 'The same "None" instance should have been returned');
-    }
-
-    #[TestDox('Map succeeds with Some')]
-    public function testMapSucceedsWithSome(): void
-    {
-        $mapped = Option::Some('abc ')->map(fn($it) => str_repeat($it, 2));
-        $this->assertTrue($mapped->isSome(), 'The mapped option should be "Some"');
-        $this->assertEquals('abc abc ', $mapped->get(), 'The mapping function was not called correctly');
-    }
-
-    #[TestDox('Map fails with Some when mapping is null')]
-    public function testMapFailsWithSomeWhenMappingIsNull(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Option::Some('oof')->map(fn($it) => null);
-    }
-
-    #[TestDox('Iter succeeds with None')]
-    public function testIterSucceedsWithNone(): void
-    {
-        $target = new class { public mixed $called = null; };
-        Option::None()->iter(function () use ($target) { $target->called = 'uh oh'; });
-        $this->assertNull($target->called, 'The function should not have been called');
-    }
-
-    #[TestDox('Iter succeeds with Some')]
-    public function testIterSucceedsWithSome(): void
-    {
-        $target = new class { public mixed $called = null; };
-        Option::Some(33)->iter(function ($it) use ($target) { $target->called = $it; });
-        $this->assertEquals(33, $target->called, 'The function should have been called with the "Some" value');
-    }
-
-    #[TestDox('Filter succeeds with None')]
-    public function testFilterSucceedsWithNone(): void
-    {
-        $tattle   = new class { public bool $called = false; };
-        $none     = Option::None();
-        $filtered = $none->filter(function () use ($tattle)
-        {
-            $tattle->called = true;
-            return true;
-        });
-        $this->assertTrue($filtered->isNone(), 'The filtered option should have been "None"');
-        $this->assertFalse($tattle->called, 'The callable should not have been called');
-        $this->assertSame($none, $filtered, 'The "None" instance returned should have been the one passed');
-    }
-
-    #[TestDox('Filter succeeds with Some when true')]
-    public function testFilterSucceedsWithSomeWhenTrue(): void
-    {
-        $some     = Option::Some(12);
-        $filtered = $some->filter(fn($it) => $it % 2 === 0);
-        $this->assertTrue($filtered->isSome(), 'The filtered option should have been "Some"');
-        $this->assertEquals(12, $filtered->get(), 'The filtered option value is incorrect');
-        $this->assertSame($some, $filtered, 'The same "Some" instance should have been returned');
-    }
-
-    #[TestDox('Filter succeeds with Some when false')]
-    public function testFilterSucceedsWithSomeWhenFalse(): void
-    {
-        $some     = Option::Some(23);
-        $filtered = $some->filter(fn($it) => $it % 2 === 0);
-        $this->assertTrue($filtered->isNone(), 'The filtered option should have been "None"');
-    }
-
-    #[TestDox('Unwrap succeeds with None')]
-    public function testUnwrapSucceedsWithNone(): void
-    {
-        $this->assertNull(Option::None()->unwrap(), '"None" should return null');
-    }
-
-    #[TestDox('Unwrap succeeds with Some')]
-    public function testUnwrapSucceedsWithSome(): void
-    {
-        $this->assertEquals('boy howdy', Option::Some('boy howdy')->unwrap(), '"Some" should return its value');
-    }
-
-    #[TestDox('Tap succeeds with Some')]
-    public function testTapSucceedsWithSome(): void
-    {
-        $value    = '';
-        $original = Option::Some('testing');
-        $tapped   = $original->tap(
-            function (Option $it) use (&$value) { $value = $it->isSome() ? $it->get() : 'none'; });
-        $this->assertEquals('testing', $value, 'The tapped function was not called');
-        $this->assertSame($original, $tapped, 'The same option should have been returned');
-    }
-
-    #[TestDox('Tap succeeds with None')]
-    public function testTapSucceedsWithNone(): void
-    {
-        $value    = '';
-        $original = Option::None();
-        $tapped   = $original->tap(
-            function (Option $it) use (&$value) { $value = $it->isSome() ? $it->get() : 'none'; });
-        $this->assertEquals('none', $value, 'The tapped function was not called');
-        $this->assertSame($original, $tapped, 'The same option should have been returned');
-    }
-
-    #[TestDox('ToArray succeeds with Some')]
-    public function testToArraySucceedsWithSome(): void
-    {
-        $arr = Option::Some('15')->toArray();
-        $this->assertNotNull($arr, 'The array should not have been null');
-        $this->assertEquals(['15'], $arr, 'The array was not created correctly');
-    }
-
-    #[TestDox('ToArray succeeds with None')]
-    public function testToArraySucceedsWithNone(): void
-    {
-        $arr = Option::None()->toArray();
-        $this->assertNotNull($arr, 'The array should not have been null');
-        $this->assertEmpty($arr, 'The array should have been empty');
-    }
-
-    #[TestDox('ToPhpOption succeeds for Some')]
-    public function testToPhpOptionSucceedsForSome(): void
-    {
-        $opt = Option::Some('php')->toPhpOption();
-        $this->assertNotNull($opt, 'The PhpOption should not have been null');
-        $this->assertInstanceOf('PhpOption\Some', $opt, 'The PhpOption should have been "Some"');
-        $this->assertTrue($opt->isDefined(), 'There should have been a value for the PhpOption');
-        $this->assertEquals('php', $opt->get(), 'The value was not correct');
-    }
-
-    #[TestDox('ToPhpOption succeeds for None')]
-    public function testToPhpOptionSucceedsForNone(): void
-    {
-        $opt = Option::None()->toPhpOption();
-        $this->assertNotNull($opt, 'The PhpOption should not have been null');
-        $this->assertInstanceOf('PhpOption\None', $opt, 'The PhpOption should have been "None"');
-        $this->assertFalse($opt->isDefined(), 'There should not have been a value for the PhpOption');
-    }
-
-    public function testSomeSucceedsWithValue(): void
-    {
-        $it = Option::Some('hello');
-        $this->assertTrue($it->isSome(), 'The option should have been "Some"');
-    }
-
-    public function testSomeFailsWithNull(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Option::Some(null);
-    }
-
-    public function testNoneSucceeds(): void
-    {
-        $it = Option::None();
-        $this->assertTrue($it->isNone(), 'The option should have been "None"');
-    }
-
-    public function testOfSucceedsWithNull(): void
-    {
-        $it = Option::of(null);
-        $this->assertTrue($it->isNone(), '"null" should have created a "None" option');
-    }
-
-    public function testOfSucceedsWithNonNull(): void
-    {
-        $it = Option::of('test');
-        $this->assertTrue($it->isSome(), 'A non-null value should have created a "Some" option');
-        $this->assertEquals('test', $it->get(), 'The value was not assigned correctly');
-    }
-
-    #[TestDox('Of succeeds with PhpOption\Some')]
-    public function testOfSucceedsWithPhpOptionSome(): void
-    {
-        $it = Option::of(Some::create('something'));
-        $this->assertTrue($it->isSome(), 'A "Some" PhpOption should have created a "Some" option');
-        $this->assertEquals('something', $it->get(), 'The value was not assigned correctly');
-    }
-
-    #[TestDox('Of succeeds with PhpOption\None')]
-    public function testOfSucceedsWithPhpOptionNone(): void
-    {
-        $it = Option::of(None::create());
-        $this->assertTrue($it->isNone(), 'A "None" PhpOption should have created a "None" option');
-    }
-}

tests/Pest.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+|--------------------------------------------------------------------------
+| Test Case
+|--------------------------------------------------------------------------
+|
+| The closure you provide to your test functions is always bound to a specific PHPUnit test
+| case class. By default, that class is "PHPUnit\Framework\TestCase". Of course, you may
+| need to change it using the "pest()" function to bind a different classes or traits.
+|
+*/
+
+// pest()->extend(Tests\TestCase::class)->in('Feature');
+
+/*
+|--------------------------------------------------------------------------
+| Expectations
+|--------------------------------------------------------------------------
+|
+| When you're writing tests, you often need to check that values meet certain conditions. The
+| "expect()" function gives you access to a set of "expectations" methods that you can use
+| to assert different things. Of course, you may extend the Expectation API at any time.
+|
+*/
+
+expect()->extend('toBeOne', function () {
+    return $this->toBe(1);
+});
+
+/*
+|--------------------------------------------------------------------------
+| Functions
+|--------------------------------------------------------------------------
+|
+| While Pest is very powerful out-of-the-box, you may have some testing code specific to your
+| project that you don't want to repeat in every file. Here you can also expose helpers as
+| global functions to help you to reduce the number of lines of code in your test files.
+|
+*/
+
+function something()
+{
+    // ..
+}

tests/ResultTest.php

@@ -1,313 +0,0 @@
-<?php
-/**
- * @author Daniel J. Summers <daniel@bitbadger.solutions>
- * @license MIT
- */
-
-declare(strict_types=1);
-
-namespace Test;
-
-use BitBadger\InspiredByFSharp\Result;
-use InvalidArgumentException;
-use PHPUnit\Framework\Attributes\TestDox;
-use PHPUnit\Framework\TestCase;
-
-/**
- * Unit tests for the Result class
- */
-class ResultTest extends TestCase
-{
-    #[TestDox('GetOK succeeds for OK result')]
-    public function testGetOKSucceedsForOKResult(): void
-    {
-        $result = Result::OK('yay');
-        $this->assertEquals('yay', $result->getOK(), 'The OK result should have been returned');
-    }
-
-    #[TestDox('GetOK fails for Error result')]
-    public function testGetOKFailsForErrorResult(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Result::Error('whoops')->getOK();
-    }
-
-    #[TestDox('GetError succeeds for Error result')]
-    public function testGetErrorSucceedsForErrorResult(): void
-    {
-        $result = Result::Error('boo');
-        $this->assertEquals('boo', $result->getError(), 'The Error result should have been returned');
-    }
-
-    #[TestDox('GetError fails for OK result')]
-    public function testGetErrorFailsForOKResult(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Result::OK('yeah')->getError();
-    }
-
-    #[TestDox('IsOK succeeds for OK result')]
-    public function testIsOKSucceedsForOKResult(): void
-    {
-        $result = Result::OK('ok');
-        $this->assertTrue($result->isOK(), 'The check for "OK" should have returned true');
-    }
-
-    #[TestDox('IsOK succeeds for Error result')]
-    public function testIsOKSucceedsForErrorResult(): void
-    {
-        $result = Result::Error('error');
-        $this->assertFalse($result->isOK(), 'The check for "OK" should have returned false');
-    }
-
-    #[TestDox('IsError succeeds for Error result')]
-    public function testIsErrorSucceedsForErrorResult(): void
-    {
-        $result = Result::Error('not ok');
-        $this->assertTrue($result->isError(), 'The check for "Error" should have returned true');
-    }
-
-    #[TestDox('IsError succeeds for OK result')]
-    public function testIsErrorSucceedsForOKResult(): void
-    {
-        $result = Result::OK('fine');
-        $this->assertFalse($result->isError(), 'The check for "Error" should have returned false');
-    }
-
-    #[TestDox('Bind succeeds for OK with OK')]
-    public function testBindSucceedsForOKWithOK(): void
-    {
-        $result = Result::OK('one')->bind(fn($it) => Result::OK("$it two"));
-        $this->assertTrue($result->isOK(), 'The result should have been OK');
-        $this->assertEquals('one two', $result->getOK(), 'The bound function was not called');
-    }
-
-    #[TestDox('Bind succeeds for OK with Error')]
-    public function testBindSucceedsForOKWithError(): void
-    {
-        $result = Result::OK('three')->bind(fn($it) => Result::Error('back to two'));
-        $this->assertTrue($result->isError(), 'The result should have been Error');
-        $this->assertEquals('back to two', $result->getError(), 'The bound function was not called');
-    }
-
-    #[TestDox('Bind succeeds for Error')]
-    public function testBindSucceedsForError(): void
-    {
-        $original = Result::Error('oops');
-        $result   = $original->bind(fn($it) => Result::OK('never mind - it worked!'));
-        $this->assertTrue($result->isError(), 'The result should have been Error');
-        $this->assertSame($original, $result, 'The same Error result should have been returned');
-    }
-
-
-    #[TestDox('Contains succeeds for Error result')]
-    public function testContainsSucceedsForErrorResult(): void
-    {
-        $this->assertFalse(Result::Error('ouch')->contains('ouch'), '"Error" should always return false');
-    }
-
-    #[TestDox('Contains succeeds for OK result when strictly equal')]
-    public function testContainsSucceedsForOKResultWhenStrictlyEqual(): void
-    {
-        $this->assertTrue(Result::OK(18)->contains(18), '"OK" with strict equality should be true');
-    }
-
-    #[TestDox('Contains succeeds for OK result when strictly unequal')]
-    public function testContainsSucceedsForOKResultWhenStrictlyUnequal(): void
-    {
-        $this->assertFalse(Result::OK(18)->contains('18'), '"OK" with strict equality should be false');
-    }
-
-    #[TestDox('Contains succeeds for OK result when loosely equal')]
-    public function testContainsSucceedsForOKResultWhenLooselyEqual(): void
-    {
-        $this->assertTrue(Result::OK(18)->contains('18', strict: false), '"OK" with loose equality should be true');
-    }
-
-    #[TestDox('Contains succeeds for OK result when loosely unequal')]
-    public function testContainsSucceedsForOKResultWhenLooselyUnequal(): void
-    {
-        $this->assertFalse(Result::OK(18)->contains(17, strict: false), '"OK" with loose equality should be false');
-    }
-
-    #[TestDox('Exists succeeds for OK result when matching')]
-    public function testExistsSucceedsForOKResultWhenMatching(): void
-    {
-        $this->assertTrue(Result::OK(14)->exists(fn($it) => $it < 100), 'Exists should have returned true');
-    }
-
-    #[TestDox('Exists succeeds for OK result when not matching')]
-    public function testExistsSucceedsForOKResultWhenNotMatching(): void
-    {
-        $this->assertFalse(Result::OK(14)->exists(fn($it) => $it > 100), 'Exists should have returned false');
-    }
-
-    #[TestDox('Exists succeeds for Error result')]
-    public function testExistsSucceedsForErrorResult(): void
-    {
-        $this->assertFalse(Result::Error(true)->exists(fn($it) => true), 'Exists should have returned false');
-    }
-
-    #[TestDox('Map succeeds for OK result')]
-    public function testMapSucceedsForOKResult(): void
-    {
-        $ok     = Result::OK('yard');
-        $mapped = $ok->map(fn($it) => strrev($it));
-        $this->assertTrue($mapped->isOK(), 'The mapped result should be "OK"');
-        $this->assertEquals('dray', $mapped->getOK(), 'The mapping function was not called correctly');
-    }
-
-    #[TestDox('Map fails for OK result when mapping is null')]
-    public function testMapFailsForOKResultWhenMappingIsNull(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Result::OK('not null')->map(fn($it) => null);
-    }
-
-    #[TestDox('Map succeeds for Error result')]
-    public function testMapSucceedsForErrorResult(): void
-    {
-        $tattle = new class { public bool $called = false; };
-        $error  = Result::Error('nope');
-        $mapped = $error->map(function () use ($tattle)
-        {
-            $tattle->called = true;
-            return 'hello';
-        });
-        $this->assertTrue($mapped->isError(), 'The mapped result should be "Error"');
-        $this->assertFalse($tattle->called, 'The mapping function should not have been called');
-        $this->assertSame($error, $mapped, 'The same "Error" instance should have been returned');
-    }
-
-    #[TestDox('MapError succeeds for OK result')]
-    public function testMapErrorSucceedsForOKResult(): void
-    {
-        $tattle = new class { public bool $called = false; };
-        $ok     = Result::OK('sure');
-        $mapped = $ok->mapError(function () use ($tattle)
-        {
-            $tattle->called = true;
-            return 'hello';
-        });
-        $this->assertTrue($mapped->isOK(), 'The mapped result should be "OK"');
-        $this->assertFalse($tattle->called, 'The mapping function should not have been called');
-        $this->assertSame($ok, $mapped, 'The same "OK" instance should have been returned');
-    }
-
-    #[TestDox('MapError succeeds for Error result')]
-    public function testMapErrorSucceedsForErrorResult(): void
-    {
-        $error  = Result::Error('taco');
-        $mapped = $error->mapError(fn($it) => str_repeat('*', strlen($it)));
-        $this->assertTrue($mapped->isError(), 'The mapped result should be "Error"');
-        $this->assertEquals('****', $mapped->getError(), 'The mapping function was not called correctly');
-    }
-
-    #[TestDox('MapError fails for Error result when mapping is null')]
-    public function testMapErrorFailsForErrorResultWhenMappingIsNull(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Result::Error('pizza')->mapError(fn($it) => null);
-    }
-
-    #[TestDox('Iter succeeds for OK result')]
-    public function testIterSucceedsForOKResult(): void
-    {
-        $target = new class { public mixed $called = null; };
-        Result::OK(77)->iter(function ($it) use ($target) { $target->called = $it; });
-        $this->assertEquals(77, $target->called, 'The function should have been called with the "OK" value');
-    }
-
-    #[TestDox('Iter succeeds for Error result')]
-    public function testIterSucceedsForErrorResult(): void
-    {
-        $target = new class { public mixed $called = null; };
-        Result::Error('')->iter(function () use ($target) { $target->called = 'uh oh'; });
-        $this->assertNull($target->called, 'The function should not have been called');
-    }
-
-    #[TestDox('ToArray succeeds for OK result')]
-    public function testToArraySucceedsForOKResult(): void
-    {
-        $arr = Result::OK('yay')->toArray();
-        $this->assertNotNull($arr, 'The array should not have been null');
-        $this->assertEquals(['yay'], $arr, 'The array was not created correctly');
-    }
-
-    #[TestDox('ToArray succeeds for Error result')]
-    public function testToArraySucceedsForErrorResult(): void
-    {
-        $arr = Result::Error('oh no')->toArray();
-        $this->assertNotNull($arr, 'The array should not have been null');
-        $this->assertEmpty($arr, 'The array should have been empty');
-    }
-
-    #[TestDox('ToOption succeeds for OK result')]
-    public function testToOptionSucceedsForOKResult()
-    {
-        $value = Result::OK(99)->toOption();
-        $this->assertTrue($value->isSome(), 'An "OK" result should map to a "Some" option');
-        $this->assertEquals(99, $value->get(), 'The value is not correct');
-    }
-
-    #[TestDox('ToOption succeeds for Error result')]
-    public function testToOptionSucceedsForErrorResult()
-    {
-        $value = Result::Error('file not found')->toOption();
-        $this->assertTrue($value->isNone(), 'An "Error" result should map to a "None" option');
-    }
-
-    #[TestDox('Tap succeeds for OK result')]
-    public function testTapSucceedsForOKResult(): void
-    {
-        $value    = '';
-        $original = Result::OK('working');
-        $tapped   = $original->tap(function (Result $it) use (&$value) {
-            $value = $it->isOK() ? 'OK: ' . $it->getOK() : 'Error: ' . $it->getError();
-        });
-        $this->assertEquals('OK: working', $value, 'The tapped function was not called');
-        $this->assertSame($original, $tapped, 'The same result should have been returned');
-    }
-
-    #[TestDox('Tap succeeds for Error result')]
-    public function testTapSucceedsForErrorResult(): void
-    {
-        $value    = '';
-        $original = Result::Error('failed');
-        $tapped   = $original->tap(function (Result $it) use (&$value) {
-            $value = $it->isOK() ? 'OK: ' . $it->getOK() : 'Error: ' . $it->getError();
-        });
-        $this->assertEquals('Error: failed', $value, 'The tapped function was not called');
-        $this->assertSame($original, $tapped, 'The same result should have been returned');
-    }
-
-    #[TestDox('OK succeeds for non null result')]
-    public function testOKSucceedsForNonNullResult(): void
-    {
-        $result = Result::OK('something');
-        $this->assertTrue($result->isOK(), 'The result should have been "OK"');
-        $this->assertEquals('something', $result->getOK(), 'The "OK" value was incorrect');
-    }
-
-    #[TestDox('OK fails for null result')]
-    public function testOKFailsForNullResult(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Result::OK(null);
-    }
-
-    #[TestDox('Error succeeds for non null result')]
-    public function testErrorSucceedsForNonNullResult(): void
-    {
-        $result = Result::Error('sad trombone');
-        $this->assertTrue($result->isError(), 'The result should have been "Error"');
-        $this->assertEquals('sad trombone', $result->getError(), 'The "Error" value was incorrect');
-    }
-
-    #[TestDox('Error fails for null result')]
-    public function testErrorFailsForNullResult(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        Result::Error(null);
-    }
-}

tests/Unit/OptionTest.php

@@ -0,0 +1,256 @@
+<?php
+/**
+ * @author Daniel J. Summers <daniel@bitbadger.solutions>
+ * @license MIT
+ */
+
+declare(strict_types=1);
+
+use BitBadger\InspiredByFSharp\Option;
+use PhpOption\{None, Some};
+
+describe('->value', function () {
+    test('retrieves the value for Some', function () {
+        expect(Option::Some(9)->value)->toBe(9);
+    });
+    test('throws an exception for None', function () {
+        expect(fn() => Option::None()->value)->toThrow(InvalidArgumentException::class);
+    });
+});
+
+describe('->isNone', function () {
+    test('returns true for None', function () {
+        expect(Option::None()->isNone)->toBeTrue();
+    });
+    test('returns false for Some', function () {
+        expect(Option::Some(8)->isNone)->toBeFalse();
+    });
+});
+
+describe('->isSome', function () {
+    test('returns false for None', function () {
+        expect(Option::None()->isSome)->toBeFalse();
+    });
+    test('returns true for Some', function () {
+        expect(Option::Some('boo')->isSome)->toBeTrue();
+    });
+});
+
+describe('->getOrDefault()', function () {
+    test('returns default value for None', function () {
+        expect(Option::None()->getOrDefault('yes'))->toBe('yes');
+    });
+    test('returns option value for Some', function () {
+        expect(Option::Some('no')->getOrDefault('yes'))->toBe('no');
+    });
+});
+
+describe('->getOrCall()', function () {
+    test('returns value from callable for None', function () {
+        expect(Option::None()->getOrCall(fn() => 'called'))->toBe('called');
+    });
+    test('returns option value for Some', function () {
+        expect(Option::Some('passed')->getOrCall(fn() => 'called'))->toBe('passed');
+    });
+});
+
+describe('->getOrThrow()', function () {
+    test('throws an exception for None', function () {
+        expect(fn() => Option::None()->getOrThrow(fn() => throw new BadMethodCallException()))
+            ->toThrow(BadMethodCallException::class);
+    });
+    test('returns option value for Some', function () {
+        expect(Option::Some('no throw')->getOrThrow(fn() => throw new BadMethodCallException()))->toBe('no throw');
+    });
+});
+
+describe('->bind()', function () {
+    test('returns None when binding against None', function () {
+        $original = Option::None();
+        $bound = $original->bind(fn($it) => Option::Some('value'));
+        expect($bound)->isNone->toBeTrue()->and($bound)->toBe($original);
+    });
+    test('returns Some when binding against Some with Some', function () {
+        expect(Option::Some('hello')->bind(fn($it) => Option::Some('goodbye')))
+            ->isSome->toBeTrue()->value->toBe('goodbye');
+    });
+    test('returns None when binding against Some with None', function () {
+        expect(Option::Some('greetings')->bind(fn($it) => Option::None()))->isNone->toBeTrue();
+    });
+});
+
+describe('->contains()', function () {
+    test('returns false for None', function () {
+        expect(Option::None()->contains(null))->toBeFalse();
+    });
+    test('returns true for Some when strict equality is matched', function () {
+        expect(Option::Some(3)->contains(3))->toBeTrue();
+    });
+    test('returns false for Some when strict equality is not matched', function () {
+        expect(Option::Some('3')->contains(3))->toBeFalse();
+    });
+    test('returns true for Some when loose equality is matched', function () {
+        expect(Option::Some('3')->contains(3, strict: false))->toBeTrue();
+    });
+    test('returns false for Some when loose equality is not matched', function () {
+        expect(Option::Some('3')->contains(4, strict: false))->toBeFalse();
+    });
+});
+
+describe('->exists()', function () {
+    test('returns false for None', function () {
+        expect(Option::None()->exists(fn($it) => true))->toBeFalse();
+    });
+    test('returns true for Some and matching condition', function () {
+        expect(Option::Some(14)->exists(fn($it) => $it < 100))->toBeTrue();
+    });
+    test('returns false for Some and non-matching condition', function () {
+        expect(Option::Some(14)->exists(fn($it) => $it > 100))->toBeFalse();
+    });
+});
+
+describe('->map()', function () {
+    test('does nothing for None', function () {
+        $tattle = new class { public bool $called = false; };
+        $none   = Option::None();
+        $mapped = $none->map(function () use ($tattle)
+        {
+            $tattle->called = true;
+            return 'hello';
+        });
+        expect($mapped)
+            ->isNone->toBeTrue()
+            ->and($tattle->called)->toBeFalse()
+            ->and($mapped)->toBe($none);
+    });
+    test('maps value for Some', function () {
+        expect(Option::Some('abc ')->map(fn($it) => str_repeat($it, 2)))
+            ->isSome->toBeTrue()->value->toBe('abc abc ');
+    });
+    test('throws an exception if mapping returns null', function () {
+        expect(fn() => Option::Some('oof')->map(fn($it) => null))->toThrow(InvalidArgumentException::class);
+    });
+});
+
+describe('->iter()', function () {
+    test('does nothing for None', function () {
+        $target = new class { public mixed $called = null; };
+        Option::None()->iter(function () use ($target) { $target->called = 'uh oh'; });
+        expect($target->called)->toBeNull();
+    });
+    test('iterates for Some', function () {
+        $target = new class { public mixed $called = null; };
+        Option::Some(33)->iter(function ($it) use ($target) { $target->called = $it; });
+        expect($target->called)->toBe(33);
+    });
+});
+
+describe('->filter()', function () {
+    test('does nothing for None', function () {
+        $tattle   = new class { public bool $called = false; };
+        $none     = Option::None();
+        $filtered = $none->filter(function () use ($tattle)
+        {
+            $tattle->called = true;
+            return true;
+        });
+        expect($filtered)
+            ->isNone->toBeTrue()
+            ->and($tattle->called)->toBeFalse()
+            ->and($filtered)->toBe($none);
+    });
+    test('returns Some when filter is matched', function () {
+        $some     = Option::Some(12);
+        $filtered = $some->filter(fn($it) => $it % 2 === 0);
+        expect($filtered)
+            ->isSome->toBeTrue()
+            ->value->toBe(12)
+            ->and($filtered)->toBe($some);
+    });
+    test('returns None when filter is not matched', function () {
+        expect(Option::Some(23)->filter(fn($it) => $it % 2 === 0)->isNone)->toBeTrue();
+    });
+});
+
+describe('->unwrap()', function () {
+    test('returns null for None', function () {
+        expect(Option::None()->unwrap())->toBeNull();
+    });
+    test('returns option value for Some', function () {
+        expect(Option::Some('boy howdy')->unwrap())->toBe('boy howdy');
+    });
+});
+
+describe('->tap()', function () {
+    test('is called for None', function () {
+        $value    = '';
+        $original = Option::None();
+        $tapped   = $original->tap(
+            function (Option $it) use (&$value) { $value = $it->isSome ? $it->value : 'none'; });
+        expect($value)->toBe('none')->and($original)->toBe($tapped);
+    });
+    test('is called for Some', function () {
+        $value    = '';
+        $original = Option::Some('testing');
+        $tapped   = $original->tap(
+            function (Option $it) use (&$value) { $value = $it->isSome ? $it->value : 'none'; });
+        expect($value)->toBe('testing')->and($original)->toBe($tapped);
+    });
+});
+
+describe('->toArray()', function () {
+    test('returns empty array for None', function () {
+        expect(Option::None()->toArray())->not->toBeNull()->toBeEmpty();
+    });
+    test('returns one-item array for Some', function () {
+        expect(Option::Some('15')->toArray())->not->toBeNull()->toBe(['15']);
+    });
+});
+
+describe('->toPhpOption()', function () {
+    test('converts None', function () {
+        expect(Option::None()->toPhpOption())
+            ->toBeInstanceOf('PhpOption\None')
+            ->not->toBeNull()
+            ->isDefined()->toBeFalse();
+    });
+    test('converts Some', function () {
+        expect(Option::Some('php')->toPhpOption())
+            ->toBeInstanceOf('PhpOption\Some')
+            ->not->toBeNull()
+            ->isDefined()->toBeTrue()
+            ->get()->toBe('php');
+    });
+});
+
+describe('::Some()', function () {
+    test('creates a Some option when given a value', function () {
+        expect(Option::Some('hello'))->not->toBeNull()->isSome->toBeTrue();
+    });
+    test('throws an exception when given null', function () {
+        expect(fn() => Option::Some(null))->toThrow(InvalidArgumentException::class);
+    });
+});
+
+describe('::None()', function () {
+    test('creates a None option', function () {
+        expect(Option::None())->not->toBeNull()->isNone->toBeTrue();
+    });
+});
+
+describe('::of()', function () {
+    test('creates a None option when given null', function () {
+        expect(Option::of(null))->not->toBeNull()->isNone->toBeTrue();
+    });
+    test('creates a Some option when given a value', function () {
+        expect(Option::of('test'))->not->toBeNull()
+            ->isSome->toBeTrue()
+            ->value->toBe('test');
+    });
+    test('creates a None option when given PhpOption\None', function () {
+        expect(Option::of(None::create()))->isNone->toBeTrue();
+    });
+    test('creates a Some option when given PhpOption\Some', function () {
+        expect(Option::of(Some::create('something')))->isSome->toBeTrue()->value->toBe('something');
+    });
+});

tests/Unit/ResultTest.php

@@ -0,0 +1,206 @@
+<?php
+/**
+ * @author Daniel J. Summers <daniel@bitbadger.solutions>
+ * @license MIT
+ */
+
+declare(strict_types=1);
+
+use BitBadger\InspiredByFSharp\{Option, Result};
+
+describe('->ok', function () {
+    test('returns OK value for OK result', function () {
+        expect(Result::OK('yay')->ok)->toBe('yay');
+    });
+    test('throws an exception for Error result', function () {
+        expect(fn() => Result::Error('whoops')->ok)->toThrow(InvalidArgumentException::class);
+    });
+});
+
+describe('->error', function () {
+    test('throws an exception for OK result', function () {
+        expect(fn() => Result::OK('yeah')->error)->toThrow(InvalidArgumentException::class);
+    });
+    test('returns Error value for Error result', function () {
+        expect(Result::Error('boo')->error)->toBe('boo');
+    });
+});
+
+describe('->isOK', function () {
+    test('returns true for OK result', function () {
+        expect(Result::OK('ok')->isOK)->toBeTrue();
+    });
+    test('returns false for Error result', function () {
+        expect(Result::Error('error')->isOK)->toBeFalse();
+    });
+});
+
+describe('->isError', function () {
+    test('returns false for OK result', function () {
+        expect(Result::OK('fine')->isError)->toBeFalse();
+    });
+    test('returns true for Error result', function () {
+        expect(Result::Error('not ok')->isError)->toBeTrue();
+    });
+});
+
+describe('->bind()', function () {
+    test('returns OK when binding against OK with OK', function () {
+        expect(Result::OK('one')->bind(fn($it) => Result::OK("$it two")))
+            ->isOK->toBeTrue()->ok->toBe('one two');
+    });
+    test('returns Error when binding against OK with Error', function () {
+        expect(Result::OK('three')->bind(fn($it) => Result::Error('back to two')))
+            ->isError->toBeTrue()->error->toBe('back to two');
+    });
+    test('returns Error when binding against Error', function () {
+        $original = Result::Error('oops');
+        $result   = $original->bind(fn($it) => Result::OK('never mind - it worked!'));
+        expect($result->isError)->toBeTrue()
+            ->and($result)->toBe($original);
+    });
+});
+
+describe('->contains()', function () {
+    test('returns true when OK is strictly equal', function () {
+        expect(Result::OK(18)->contains(18))->toBeTrue();
+    });
+    test('returns false when OK is not strictly equal', function () {
+        expect(Result::OK(18)->contains('18'))->toBeFalse();
+    });
+    test('returns true when OK is loosely equal', function () {
+        expect(Result::OK(18)->contains('18', strict: false))->toBeTrue();
+    });
+    test('returns false when OK is not loosely equal', function () {
+        expect(Result::OK(18)->contains(17, strict: false))->toBeFalse();
+    });
+    test('returns false for Error', function () {
+        expect(Result::Error('ouch')->contains('ouch'))->toBeFalse();
+    });
+});
+
+describe('->exists()', function () {
+    test('returns true for OK when condition matches', function () {
+        expect(Result::OK(14)->exists(fn($it) => $it < 100))->toBeTrue();
+    });
+    test('returns false for OK when condition does not match', function () {
+        expect(Result::OK(14)->exists(fn($it) => $it > 100))->toBeFalse();
+    });
+    test('returns false for Error', function () {
+        expect(Result::Error(true)->exists(fn($it) => true))->toBeFalse();
+    });
+});
+
+describe('->map()', function () {
+    test('maps value for OK', function () {
+        expect(Result::OK('yard')->map(fn($it) => strrev($it)))
+            ->isOK->toBeTrue()->ok->toBe('dray');
+    });
+    test('throws an exception for OK when mapping result is null', function () {
+        expect(fn() => Result::OK('not null')->map(fn($it) => null))->toThrow(InvalidArgumentException::class);
+    });
+    test('does nothing for Error', function () {
+        $tattle = new class { public bool $called = false; };
+        $error  = Result::Error('nope');
+        $mapped = $error->map(function () use ($tattle)
+        {
+            $tattle->called = true;
+            return 'hello';
+        });
+        expect($mapped)
+            ->isError->toBeTrue()
+            ->and($tattle->called)->toBeFalse()
+            ->and($mapped)->toBe($error);
+    });
+});
+
+describe('->mapError()', function () {
+    test('does nothing for OK', function () {
+        $tattle = new class { public bool $called = false; };
+        $ok     = Result::OK('sure');
+        $mapped = $ok->mapError(function () use ($tattle)
+        {
+            $tattle->called = true;
+            return 'hello';
+        });
+        expect($mapped)
+            ->isOK->toBeTrue()
+            ->and($tattle->called)->toBeFalse()
+            ->and($mapped)->toBe($ok);
+    });
+    test('maps value for Error', function () {
+        expect(Result::Error('taco')->mapError(fn($it) => str_repeat('*', strlen($it))))
+            ->isError->toBeTrue()->error->toBe('****');
+    });
+    test('throws an exception for Error when mapping result is null', function () {
+        expect(fn() => Result::Error('pizza')->mapError(fn($it) => null))->toThrow(InvalidArgumentException::class);
+    });
+});
+
+describe('->iter()', function () {
+    test('iterates for OK', function () {
+        $target = new class { public mixed $called = null; };
+        Result::OK(77)->iter(function ($it) use ($target) { $target->called = $it; });
+        expect($target->called)->toBe(77);
+    });
+    test('does nothing for Error', function () {
+        $target = new class { public mixed $called = null; };
+        Result::Error('')->iter(function () use ($target) { $target->called = 'uh oh'; });
+        expect($target->called)->toBeNull();
+    });
+});
+
+describe('->toArray()', function () {
+    test('returns a one-item array for OK', function () {
+        expect(Result::OK('yay')->toArray())->not->toBeNull()->toBe(['yay']);
+    });
+    test('returns an empty array for Error', function () {
+        expect(Result::Error('oh no')->toArray())->not->toBeNull()->toBeEmpty();
+    });
+});
+
+describe('->toOption()', function () {
+    test('returns a Some option for OK', function () {
+        expect(Result::OK(99)->toOption())->isSome->toBeTrue()->value->toBe(99);
+    });
+    test('returns a None option for Error', function () {
+        expect(Result::Error('file not found')->toOption())->isNone->toBeTrue();
+    });
+});
+
+describe('->tap()', function () {
+    test('is called for OK', function () {
+        $value = '';
+        $original = Result::OK('working');
+        $tapped = $original->tap(function (Result $it) use (&$value) {
+            $value = $it->isOK ? 'OK: ' . $it->ok : 'Error: ' . $it->error;
+        });
+        expect($value)->toBe('OK: working')->and($tapped)->toBe($original);
+    });
+    test('is called for Error', function () {
+        $value    = '';
+        $original = Result::Error('failed');
+        $tapped   = $original->tap(function (Result $it) use (&$value) {
+            $value = $it->isOK ? 'OK: ' . $it->ok : 'Error: ' . $it->error;
+        });
+        expect($value)->toBe('Error: failed')->and($tapped)->toBe($original);
+    });
+});
+
+describe('::OK()', function () {
+    test('creates an OK result for a non-null value', function () {
+        expect(Result::OK('something'))->isOK->toBeTrue()->ok->toBe('something');
+    });
+    test('throws an exception for OK with a null value', function () {
+        expect(fn() => Result::OK(null))->toThrow(InvalidArgumentException::class);
+    });
+});
+
+describe('::Error()', function () {
+    test('creates an Error result for a non-null value', function () {
+        expect(Result::Error('sad trombone'))->isError->toBeTrue()->error->toBe('sad trombone');
+    });
+    test('throws an exception for Error with a null value', function () {
+        expect(fn() => Result::Error(null))->toThrow(InvalidArgumentException::class);
+    });
+});