(Yet Another) Assertions implementation

composer.json

@@ -28,7 +28,8 @@
         "laravel/framework": "^5.4|^6.0|^7.0|^8.0"
     },
     "require-dev": {
-        "orchestra/testbench": "~3.0"
+        "orchestra/testbench": "^3.4|^4.0|^5.0",
+        "phpunit/phpunit": "~5.7|~6.0|^7.0|^8.0|^9.0"
     },
     "extra": {
         "laravel": {

ide_helpers.php

@@ -0,0 +1,39 @@
+<?php
+
+/** @noinspection PhpUndefinedClassInspection */
+/** @noinspection PhpFullyQualifiedNameUsageInspection */
+/** @noinspection PhpUnusedAliasInspection */
+
+namespace Illuminate\Testing {
+
+    /**
+     * @see \Inertia\Assertions
+     *
+     * @method self assertInertia($component = null, $props = [])
+     * @method self assertInertiaHas($key, $value = null)
+     * @method self assertInertiaHasAll(array $bindings)
+     * @method self assertInertiaMissing($key)
+     * @method array inertiaProps()
+     */
+    class TestResponse
+    {
+        //
+    }
+}
+
+namespace Illuminate\Foundation\Testing {
+
+    /**
+     * @see \Inertia\Assertions
+     *
+     * @method self assertInertia($component = null, $props = [])
+     * @method self assertInertiaHas($key, $value = null)
+     * @method self assertInertiaHasAll(array $bindings)
+     * @method self assertInertiaMissing($key)
+     * @method array inertiaProps()
+     */
+    class TestResponse
+    {
+        //
+    }
+}

src/Assertions.php

@@ -0,0 +1,92 @@
+<?php
+
+namespace Inertia;
+
+use Closure;
+use Illuminate\Contracts\Support\Arrayable;
+use Illuminate\Contracts\Support\Responsable;
+use Illuminate\Support\Arr;
+use PHPUnit\Framework\Assert as PHPUnit;
+
+class Assertions
+{
+    public function assertInertia()
+    {
+        return function ($component = null, $props = []) {
+            $this->assertViewHas('page');
+
+            tap($this->viewData('page'), function ($view) {
+                PHPUnit::assertArrayHasKey('component', $view);
+                PHPUnit::assertArrayHasKey('props', $view);
+                PHPUnit::assertArrayHasKey('url', $view);
+                PHPUnit::assertArrayHasKey('version', $view);
+            });
+
+            if (! is_null($component)) {
+                PHPUnit::assertEquals($component, $this->viewData('page')['component']);
+            }
+
+            $this->assertInertiaHasAll($props);
+
+            return $this;
+        };
+    }
+
+    public function inertiaProps()
+    {
+        return function () {
+            $this->assertInertia();
+
+            return $this->viewData('page')['props'];
+        };
+    }
+
+    public function assertInertiaHas()
+    {
+        return function ($key, $value = null) {
+            if (is_array($key)) {
+                return $this->assertInertiaHasAll($key);
+            }
+
+            if (is_null($value)) {
+                PHPUnit::assertTrue(Arr::has($this->inertiaProps(), $key));
+            } elseif ($value instanceof Closure) {
+                PHPUnit::assertTrue($value(Arr::get($this->inertiaProps(), $key)));
+            } elseif ($value instanceof Arrayable) {
+                PHPUnit::assertEquals($value->toArray(), Arr::get($this->inertiaProps(), $key));
+            } elseif ($value instanceof Responsable) {
+                PHPUnit::assertEquals($value->toResponse($this)->getData(), Arr::get($this->inertiaProps(), $key));
+            } else {
+                PHPUnit::assertEquals($value, Arr::get($this->inertiaProps(), $key));
+            }
+
+            return $this;
+        };
+    }
+
+    public function assertInertiaHasAll()
+    {
+        return function (array $bindings) {
+            foreach ($bindings as $key => $value) {
+                if (is_int($key)) {
+                    $this->assertInertiaHas($value);
+                } else {
+                    $this->assertInertiaHas($key, $value);
+                }
+            }
+
+            return $this;
+        };
+    }
+
+    public function assertInertiaMissing()
+    {
+        return function ($key) {
+            $this->assertInertia();
+
+            PHPUnit::assertFalse(Arr::has($this->inertiaProps(), $key));
+
+            return $this;
+        };
+    }
+}

src/ServiceProvider.php

@@ -2,13 +2,17 @@
 
 namespace Inertia;
 
+use LogicException;
 use Illuminate\Http\Request;
 use Illuminate\Routing\Router;
 use Illuminate\Support\Collection;
+use Illuminate\Support\Facades\App;
+use Illuminate\Testing\TestResponse;
 use Illuminate\Contracts\Http\Kernel;
 use Illuminate\Support\Facades\Blade;
 use Illuminate\Support\Facades\Session;
 use Illuminate\Support\ServiceProvider as BaseServiceProvider;
+use Illuminate\Foundation\Testing\TestResponse as LegacyTestResponse;
 
 class ServiceProvider extends BaseServiceProvider
 {
@@ -24,6 +28,10 @@ public function boot()
         $this->registerRouterMacro();
         $this->registerMiddleware();
         $this->shareValidationErrors();
+
+        if (App::runningUnitTests()) {
+            $this->registerTestingMacros();
+        }
     }
 
     protected function registerBladeDirective()
@@ -54,6 +62,25 @@ protected function registerMiddleware()
         $this->app[Kernel::class]->pushMiddleware(Middleware::class);
     }
 
+    protected function registerTestingMacros()
+    {
+        // Laravel >= 7.0
+        if (class_exists(TestResponse::class)) {
+            TestResponse::mixin(new Assertions());
+
+            return;
+        }
+
+        // Laravel <= 6.0
+        if (class_exists(LegacyTestResponse::class)) {
+            LegacyTestResponse::mixin(new Assertions());
+
+            return;
+        }
+
+        throw new LogicException('Could not detect TestResponse class.');
+    }
+
     protected function shareValidationErrors()
     {
         if (Inertia::getShared('errors')) {