feat: move Expectations API out of external plugin

src/Concerns/Expectations.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Concerns;
+
+use Pest\Expectation;
+
+/**
+ * @internal
+ */
+trait Expectations
+{
+    /**
+     * Creates a new expectation.
+     *
+     * @param mixed $value
+     */
+    public function expect($value): Expectation
+    {
+        return new Expectation($value);
+    }
+}

src/Concerns/Extendable.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Concerns;
+
+use Closure;
+use Pest\HigherOrderExpectation;
+
+/**
+ * @internal
+ */
+trait Extendable
+{
+    /**
+     * @var array<string, Closure>
+     */
+    private static $extends = [];
+
+    /**
+     * Register a custom extend.
+     */
+    public static function extend(string $name, Closure $extend): void
+    {
+        static::$extends[$name] = $extend;
+    }
+
+    /**
+     * Checks if extend is registered.
+     */
+    public static function hasExtend(string $name): bool
+    {
+        return array_key_exists($name, static::$extends);
+    }
+
+    /**
+     * Dynamically handle calls to the class.
+     *
+     * @param array<int, mixed> $parameters
+     *
+     * @return mixed
+     */
+    public function __call(string $method, array $parameters)
+    {
+        if (!static::hasExtend($method)) {
+            return new HigherOrderExpectation($this, $method, $parameters);
+        }
+
+        /** @var Closure $extend */
+        $extend = static::$extends[$method]->bindTo($this, static::class);
+
+        return $extend(...$parameters);
+    }
+}

src/Each.php

@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest;
+
+/**
+ * @internal
+ *
+ * @mixin Expectation
+ */
+final class Each
+{
+    /**
+     * @var Expectation
+     */
+    private $original;
+
+    /**
+     * @var bool
+     */
+    private $opposite = false;
+
+    /**
+     * Creates an expectation on each item of the iterable "value".
+     */
+    public function __construct(Expectation $original)
+    {
+        $this->original = $original;
+    }
+
+    /**
+     * Creates a new expectation.
+     *
+     * @param mixed $value
+     */
+    public function and($value): Expectation
+    {
+        return $this->original->and($value);
+    }
+
+    /**
+     * Creates the opposite expectation for the value.
+     */
+    public function not(): Each
+    {
+        $this->opposite = true;
+
+        return $this;
+    }
+
+    /**
+     * Dynamically calls methods on the class with the given arguments on each item.
+     *
+     * @param array<int|string, mixed> $arguments
+     */
+    public function __call(string $name, array $arguments): Each
+    {
+        foreach ($this->original->value as $item) {
+            /* @phpstan-ignore-next-line */
+            $this->opposite ? expect($item)->not()->$name(...$arguments) : expect($item)->$name(...$arguments);
+        }
+
+        $this->opposite = false;
+
+        return $this;
+    }
+
+    /**
+     * Dynamically calls methods on the class without any arguments on each item.
+     */
+    public function __get(string $name): Each
+    {
+        /* @phpstan-ignore-next-line */
+        return $this->$name();
+    }
+}

src/Expectation.php

@@ -0,0 +1,714 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest;
+
+use BadMethodCallException;
+use Pest\Concerns\Extendable;
+use PHPUnit\Framework\Assert;
+use PHPUnit\Framework\Constraint\Constraint;
+use SebastianBergmann\Exporter\Exporter;
+
+/**
+ * @internal
+ *
+ * @property Expectation $not  Creates the opposite expectation.
+ * @property Each        $each Creates an expectation on each element on the traversable value.
+ */
+final class Expectation
+{
+    use Extendable;
+
+    /**
+     * The expectation value.
+     *
+     * @readonly
+     *
+     * @var mixed
+     */
+    public $value;
+
+    /**
+     * The exporter instance, if any.
+     *
+     * @readonly
+     *
+     * @var Exporter|null
+     */
+    private $exporter;
+
+    /**
+     * Creates a new expectation.
+     *
+     * @param mixed $value
+     */
+    public function __construct($value)
+    {
+        $this->value = $value;
+    }
+
+    /**
+     * Creates a new expectation.
+     *
+     * @param mixed $value
+     */
+    public function and($value): Expectation
+    {
+        return new self($value);
+    }
+
+    /**
+     * Dump the expectation value and end the script.
+     *
+     * @param mixed $arguments
+     *
+     * @return never
+     */
+    public function dd(...$arguments): void
+    {
+        if (function_exists('dd')) {
+            dd($this->value, ...$arguments);
+        }
+
+        var_dump($this->value);
+
+        exit(1);
+    }
+
+    /**
+     * Send the expectation value to Ray along with all given arguments.
+     *
+     * @param mixed $arguments
+     */
+    public function ray(...$arguments): self
+    {
+        if (function_exists('ray')) {
+            // @phpstan-ignore-next-line
+            ray($this->value, ...$arguments);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Creates the opposite expectation for the value.
+     */
+    public function not(): OppositeExpectation
+    {
+        return new OppositeExpectation($this);
+    }
+
+    /**
+     * Creates an expectation on each item of the iterable "value".
+     */
+    public function each(callable $callback = null): Each
+    {
+        if (!is_iterable($this->value)) {
+            throw new BadMethodCallException('Expectation value is not iterable.');
+        }
+
+        if (is_callable($callback)) {
+            foreach ($this->value as $item) {
+                $callback(expect($item));
+            }
+        }
+
+        return new Each($this);
+    }
+
+    /**
+     * Allows you to specify a sequential set of expectations for each item in a iterable "value".
+     */
+    public function sequence(callable ...$callbacks): Expectation
+    {
+        if (!is_iterable($this->value)) {
+            throw new BadMethodCallException('Expectation value is not iterable.');
+        }
+
+        $value  = is_array($this->value) ? $this->value : iterator_to_array($this->value);
+        $keys   = array_keys($value);
+        $values = array_values($value);
+
+        $index = 0;
+
+        while (count($callbacks) < count($values)) {
+            $callbacks[] = $callbacks[$index];
+            $index       = $index < count($values) - 1 ? $index + 1 : 0;
+        }
+
+        foreach ($values as $key => $item) {
+            call_user_func($callbacks[$key], expect($item), expect($keys[$key]));
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that two variables have the same type and
+     * value. Used on objects, it asserts that two
+     * variables reference the same object.
+     *
+     * @param mixed $expected
+     */
+    public function toBe($expected): Expectation
+    {
+        Assert::assertSame($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is empty.
+     */
+    public function toBeEmpty(): Expectation
+    {
+        Assert::assertEmpty($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is true.
+     */
+    public function toBeTrue(): Expectation
+    {
+        Assert::assertTrue($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is false.
+     */
+    public function toBeFalse(): Expectation
+    {
+        Assert::assertFalse($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is greater than $expected.
+     *
+     * @param int|float $expected
+     */
+    public function toBeGreaterThan($expected): Expectation
+    {
+        Assert::assertGreaterThan($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is greater than or equal to $expected.
+     *
+     * @param int|float $expected
+     */
+    public function toBeGreaterThanOrEqual($expected): Expectation
+    {
+        Assert::assertGreaterThanOrEqual($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is less than or equal to $expected.
+     *
+     * @param int|float $expected
+     */
+    public function toBeLessThan($expected): Expectation
+    {
+        Assert::assertLessThan($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is less than $expected.
+     *
+     * @param int|float $expected
+     */
+    public function toBeLessThanOrEqual($expected): Expectation
+    {
+        Assert::assertLessThanOrEqual($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that $needle is an element of the value.
+     *
+     * @param mixed $needle
+     */
+    public function toContain($needle): Expectation
+    {
+        if (is_string($this->value)) {
+            Assert::assertStringContainsString($needle, $this->value);
+        } else {
+            Assert::assertContains($needle, $this->value);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value starts with $expected.
+     */
+    public function toStartWith(string $expected): Expectation
+    {
+        Assert::assertStringStartsWith($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value ends with $expected.
+     */
+    public function toEndWith(string $expected): Expectation
+    {
+        Assert::assertStringEndsWith($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that $count matches the number of elements of the value.
+     */
+    public function toHaveCount(int $count): Expectation
+    {
+        Assert::assertCount($count, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value contains the property $name.
+     *
+     * @param mixed $value
+     */
+    public function toHaveProperty(string $name, $value = null): Expectation
+    {
+        $this->toBeObject();
+
+        Assert::assertTrue(property_exists($this->value, $name));
+
+        if (func_num_args() > 1) {
+            /* @phpstan-ignore-next-line */
+            Assert::assertEquals($value, $this->value->{$name});
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that two variables have the same value.
+     *
+     * @param mixed $expected
+     */
+    public function toEqual($expected): Expectation
+    {
+        Assert::assertEquals($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that two variables have the same value.
+     * The contents of $expected and the $this->value are
+     * canonicalized before they are compared. For instance, when the two
+     * variables $expected and $this->value are arrays, then these arrays
+     * are sorted before they are compared. When $expected and $this->value
+     * are objects, each object is converted to an array containing all
+     * private, protected and public attributes.
+     *
+     * @param mixed $expected
+     */
+    public function toEqualCanonicalizing($expected): Expectation
+    {
+        Assert::assertEqualsCanonicalizing($expected, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the absolute difference between the value and $expected
+     * is lower than $delta.
+     *
+     * @param mixed $expected
+     */
+    public function toEqualWithDelta($expected, float $delta): Expectation
+    {
+        Assert::assertEqualsWithDelta($expected, $this->value, $delta);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is infinite.
+     */
+    public function toBeInfinite(): Expectation
+    {
+        Assert::assertInfinite($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is an instance of $class.
+     *
+     * @param string $class
+     */
+    public function toBeInstanceOf($class): Expectation
+    {
+        /* @phpstan-ignore-next-line */
+        Assert::assertInstanceOf($class, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is an array.
+     */
+    public function toBeArray(): Expectation
+    {
+        Assert::assertIsArray($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type bool.
+     */
+    public function toBeBool(): Expectation
+    {
+        Assert::assertIsBool($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type callable.
+     */
+    public function toBeCallable(): Expectation
+    {
+        Assert::assertIsCallable($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type float.
+     */
+    public function toBeFloat(): Expectation
+    {
+        Assert::assertIsFloat($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type int.
+     */
+    public function toBeInt(): Expectation
+    {
+        Assert::assertIsInt($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type iterable.
+     */
+    public function toBeIterable(): Expectation
+    {
+        Assert::assertIsIterable($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type numeric.
+     */
+    public function toBeNumeric(): Expectation
+    {
+        Assert::assertIsNumeric($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type object.
+     */
+    public function toBeObject(): Expectation
+    {
+        Assert::assertIsObject($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type resource.
+     */
+    public function toBeResource(): Expectation
+    {
+        Assert::assertIsResource($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type scalar.
+     */
+    public function toBeScalar(): Expectation
+    {
+        Assert::assertIsScalar($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is of type string.
+     */
+    public function toBeString(): Expectation
+    {
+        Assert::assertIsString($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a JSON string.
+     */
+    public function toBeJson(): Expectation
+    {
+        Assert::assertIsString($this->value);
+        Assert::assertJson($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is NAN.
+     */
+    public function toBeNan(): Expectation
+    {
+        Assert::assertNan($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is null.
+     */
+    public function toBeNull(): Expectation
+    {
+        Assert::assertNull($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value array has the provided $key.
+     *
+     * @param string|int $key
+     * @param mixed      $value
+     */
+    public function toHaveKey($key, $value = null): Expectation
+    {
+        if (is_object($this->value) && method_exists($this->value, 'toArray')) {
+            $array = $this->value->toArray();
+        } else {
+            $array = (array) $this->value;
+        }
+
+        Assert::assertArrayHasKey($key, $array);
+
+        if (func_num_args() > 1) {
+            Assert::assertEquals($value, $array[$key]);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value array has the provided $keys.
+     *
+     * @param array<int, int|string> $keys
+     */
+    public function toHaveKeys(array $keys): Expectation
+    {
+        foreach ($keys as $key) {
+            $this->toHaveKey($key);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a directory.
+     */
+    public function toBeDirectory(): Expectation
+    {
+        Assert::assertDirectoryExists($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a directory and is readable.
+     */
+    public function toBeReadableDirectory(): Expectation
+    {
+        Assert::assertDirectoryIsReadable($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a directory and is writable.
+     */
+    public function toBeWritableDirectory(): Expectation
+    {
+        Assert::assertDirectoryIsWritable($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a file.
+     */
+    public function toBeFile(): Expectation
+    {
+        Assert::assertFileExists($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a file and is readable.
+     */
+    public function toBeReadableFile(): Expectation
+    {
+        Assert::assertFileIsReadable($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value is a file and is writable.
+     */
+    public function toBeWritableFile(): Expectation
+    {
+        Assert::assertFileIsWritable($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value array matches the given array subset.
+     *
+     * @param array<int|string, mixed> $array
+     */
+    public function toMatchArray($array): Expectation
+    {
+        if (is_object($this->value) && method_exists($this->value, 'toArray')) {
+            $valueAsArray = $this->value->toArray();
+        } else {
+            $valueAsArray = (array) $this->value;
+        }
+
+        foreach ($array as $key => $value) {
+            Assert::assertArrayHasKey($key, $valueAsArray);
+
+            Assert::assertEquals(
+                $value,
+                $valueAsArray[$key],
+                sprintf(
+                    'Failed asserting that an array has a key %s with the value %s.',
+                    $this->export($key),
+                    $this->export($valueAsArray[$key]),
+                ),
+            );
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value object matches a subset
+     * of the properties of an given object.
+     *
+     * @param array<string, mixed>|object $object
+     */
+    public function toMatchObject($object): Expectation
+    {
+        foreach ((array) $object as $property => $value) {
+            Assert::assertTrue(property_exists($this->value, $property));
+
+            /* @phpstan-ignore-next-line */
+            $propertyValue = $this->value->{$property};
+            Assert::assertEquals(
+                $value,
+                $propertyValue,
+                sprintf(
+                    'Failed asserting that an object has a property %s with the value %s.',
+                    $this->export($property),
+                    $this->export($propertyValue),
+                ),
+            );
+        }
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value matches a regular expression.
+     */
+    public function toMatch(string $expression): Expectation
+    {
+        Assert::assertMatchesRegularExpression($expression, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Asserts that the value matches a constraint.
+     */
+    public function toMatchConstraint(Constraint $constraint): Expectation
+    {
+        Assert::assertThat($this->value, $constraint);
+
+        return $this;
+    }
+
+    /**
+     * Exports the given value.
+     *
+     * @param mixed $value
+     */
+    private function export($value): string
+    {
+        if ($this->exporter === null) {
+            $this->exporter = new Exporter();
+        }
+
+        return $this->exporter->export($value);
+    }
+
+    /**
+     * Dynamically calls methods on the class without any arguments
+     * or creates a new higher order expectation.
+     *
+     * @return Expectation|HigherOrderExpectation
+     */
+    public function __get(string $name)
+    {
+        if (!method_exists($this, $name) && !static::hasExtend($name)) {
+            return new HigherOrderExpectation($this, $name);
+        }
+
+        /* @phpstan-ignore-next-line */
+        return $this->{$name}();
+    }
+}

src/Factories/TestCaseFactory.php

@@ -80,6 +80,7 @@ final class TestCaseFactory
      */
     public $traits = [
         Concerns\TestCase::class,
+        Concerns\Expectations::class,
     ];
 
     /**

src/Functions.php

@@ -3,15 +3,33 @@
 declare(strict_types=1);
 
 use Pest\Datasets;
+use Pest\Expectation;
 use Pest\PendingObjects\AfterEachCall;
 use Pest\PendingObjects\BeforeEachCall;
 use Pest\PendingObjects\TestCall;
 use Pest\PendingObjects\UsesCall;
 use Pest\Support\Backtrace;
+use Pest\Support\Extendable;
 use Pest\Support\HigherOrderTapProxy;
 use Pest\TestSuite;
 use PHPUnit\Framework\TestCase;
 
+/**
+ * Creates a new expectation.
+ *
+ * @param mixed $value the Value
+ *
+ * @return Expectation|Extendable
+ */
+function expect($value = null)
+{
+    if (func_num_args() === 0) {
+        return new Extendable(Expectation::class);
+    }
+
+    return new Expectation($value);
+}
+
 if (!function_exists('beforeAll')) {
     /**
      * Runs the given closure before all tests in the current file.

src/HigherOrderExpectation.php

@@ -0,0 +1,147 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest;
+
+use Pest\Concerns\Expectations;
+
+/**
+ * @internal
+ *
+ * @mixin Expectation
+ */
+final class HigherOrderExpectation
+{
+    use Expectations;
+
+    /**
+     * @var Expectation
+     */
+    private $original;
+
+    /**
+     * @var Expectation|Each
+     */
+    private $expectation;
+
+    /**
+     * @var bool
+     */
+    private $opposite = false;
+
+    /**
+     * @var string
+     */
+    private $name;
+
+    /**
+     * Creates a new higher order expectation.
+     *
+     * @param array<int|string, mixed>|null $parameters
+     * @phpstan-ignore-next-line
+     */
+    public function __construct(Expectation $original, string $name, ?array $parameters = null)
+    {
+        $this->original = $original;
+        $this->name     = $name;
+
+        $this->expectation = $this->expect(
+            is_null($parameters) ? $this->getPropertyValue() : $this->getMethodValue($parameters)
+        );
+    }
+
+    /**
+     * Retrieves the property value from the original expectation.
+     *
+     * @return mixed
+     */
+    private function getPropertyValue()
+    {
+        if (is_array($this->original->value)) {
+            return $this->original->value[$this->name];
+        }
+
+        // @phpstan-ignore-next-line
+        return $this->original->value->{$this->name};
+    }
+
+    /**
+     * Retrieves the value of the method from the original expectation.
+     *
+     * @param array<int|string, mixed> $arguments
+     *
+     * @return mixed
+     */
+    private function getMethodValue(array $arguments)
+    {
+        // @phpstan-ignore-next-line
+        return $this->original->value->{$this->name}(...$arguments);
+    }
+
+    /**
+     * Creates the opposite expectation for the value.
+     */
+    public function not(): HigherOrderExpectation
+    {
+        $this->opposite = !$this->opposite;
+
+        return $this;
+    }
+
+    /**
+     * Dynamically calls methods on the class with the given arguments.
+     *
+     * @param array<int|string, mixed> $arguments
+     */
+    public function __call(string $name, array $arguments): self
+    {
+        if (!$this->originalHasMethod($name)) {
+            return new self($this->original, $name, $arguments);
+        }
+
+        return $this->performAssertion($name, $arguments);
+    }
+
+    /**
+     * Accesses properties in the value or in the expectation.
+     */
+    public function __get(string $name): self
+    {
+        if ($name === 'not') {
+            return $this->not();
+        }
+
+        if (!$this->originalHasMethod($name)) {
+            return new self($this->original, $name);
+        }
+
+        return $this->performAssertion($name, []);
+    }
+
+    /**
+     * Determines if the original expectation has the given method name.
+     */
+    private function originalHasMethod(string $name): bool
+    {
+        return method_exists($this->original, $name) || $this->original::hasExtend($name);
+    }
+
+    /**
+     * Performs the given assertion with the current expectation.
+     *
+     * @param array<int|string, mixed> $arguments
+     */
+    private function performAssertion(string $name, array $arguments): self
+    {
+        $expectation = $this->opposite
+            ? $this->expectation->not()
+            : $this->expectation;
+
+        $this->expectation = $expectation->{$name}(...$arguments); // @phpstan-ignore-line
+
+        $this->opposite = false;
+
+        return $this;
+    }
+}

src/OppositeExpectation.php

@@ -0,0 +1,99 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest;
+
+use PHPUnit\Framework\ExpectationFailedException;
+use SebastianBergmann\Exporter\Exporter;
+
+/**
+ * @internal
+ *
+ * @mixin Expectation
+ */
+final class OppositeExpectation
+{
+    /**
+     * @var Expectation
+     */
+    private $original;
+
+    /**
+     * Creates a new opposite expectation.
+     */
+    public function __construct(Expectation $original)
+    {
+        $this->original = $original;
+    }
+
+    /**
+     * Asserts that the value array not has the provided $keys.
+     *
+     * @param array<int, int|string> $keys
+     */
+    public function toHaveKeys(array $keys): Expectation
+    {
+        foreach ($keys as $key) {
+            try {
+                $this->original->toHaveKey($key);
+            } catch (ExpectationFailedException $e) {
+                continue;
+            }
+
+            $this->throwExpectationFailedException('toHaveKey', [$key]);
+        }
+
+        return $this->original;
+    }
+
+    /**
+     * Handle dynamic method calls into the original expectation.
+     *
+     * @param array<int, mixed> $arguments
+     */
+    public function __call(string $name, array $arguments): Expectation
+    {
+        try {
+            /* @phpstan-ignore-next-line */
+            $this->original->{$name}(...$arguments);
+        } catch (ExpectationFailedException $e) {
+            return $this->original;
+        }
+
+        // @phpstan-ignore-next-line
+        $this->throwExpectationFailedException($name, $arguments);
+    }
+
+    /**
+     * Handle dynamic properties gets into the original expectation.
+     */
+    public function __get(string $name): Expectation
+    {
+        try {
+            /* @phpstan-ignore-next-line */
+            $this->original->{$name};
+        } catch (ExpectationFailedException $e) {
+            return $this->original;
+        }
+
+        // @phpstan-ignore-next-line
+        $this->throwExpectationFailedException($name);
+    }
+
+    /**
+     * Creates a new expectation failed exception with a nice readable message.
+     *
+     * @param array<int, mixed> $arguments
+     */
+    private function throwExpectationFailedException(string $name, array $arguments = []): void
+    {
+        $exporter = new Exporter();
+
+        $toString = function ($argument) use ($exporter): string {
+            return $exporter->shortenedExport($argument);
+        };
+
+        throw new ExpectationFailedException(sprintf('Expecting %s not %s %s.', $toString($this->original->value), strtolower((string) preg_replace('/(?<!\ )[A-Z]/', ' $0', $name)), implode(' ', array_map(function ($argument) use ($toString): string { return $toString($argument); }, $arguments))));
+    }
+}

src/Support/Extendable.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Support;
+
+use Closure;
+
+final class Extendable
+{
+    /**
+     * The extendable class.
+     *
+     * @var string
+     */
+    private $extendableClass;
+
+    /**
+     * Creates a new extendable instance.
+     */
+    public function __construct(string $extendableClass)
+    {
+        $this->extendableClass = $extendableClass;
+    }
+
+    /**
+     * Register a custom extend.
+     */
+    public function extend(string $name, Closure $extend): void
+    {
+        $this->extendableClass::extend($name, $extend);
+    }
+}