diff --git a/.atoum.php b/.atoum.php
new file mode 100644
index 0000000..9e0c05e
--- /dev/null
+++ b/.atoum.php
@@ -0,0 +1,6 @@
+<?php
+
+$php = getenv('PHP_EXECUTABLE') ?: 'php';
+
+$runner->setPhpPath($php.' -dextension='.__DIR__.'/ext/modules/wasm.so');
+$runner->addTestsFromDirectory('tests');
diff --git a/.github/workflows/doc.yaml b/.github/workflows/doc.yaml
index 9eefdf0..e38451a 100644
--- a/.github/workflows/doc.yaml
+++ b/.github/workflows/doc.yaml
@@ -18,6 +18,11 @@ jobs:
           php-version: 7.4
       - name: Checkout code
         uses: actions/checkout@v2
+      - name: Configure
+        run: |
+          cd ext
+          phpize
+          ./configure
       - name: Build
         run: |
           make documentation
diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index 7919e0b..4eaba00 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -82,6 +82,10 @@ jobs:
         run: |
           cd ext
           make examples || ${{ matrix.allow_failure }}
+      - name: Run tests (unit)
+        # TODO(jubianchi): Remove allow_failure once PHP 7.3 & 7.4 are supported
+        run: |
+          make unit || ${{ matrix.allow_failure }}
       - name: Archive test results
         if: ${{ failure() }}
         uses: actions/upload-artifact@v2
diff --git a/.php_cs b/.php_cs
index c59e541..0e71c89 100644
--- a/.php_cs
+++ b/.php_cs
@@ -3,12 +3,14 @@
 $finder = PhpCsFixer\Finder::create()
     ->notName('wasmer_vec.stub.php')
     ->in('ext/src')
+    ->in('src')
 ;
 
 $config = new PhpCsFixer\Config();
 
 return $config->setRules([
         '@PSR2' => true,
+        '@Symfony' => true,
         'strict_param' => true,
         'phpdoc_align' => true,
     ])
diff --git a/Makefile b/Makefile
index 3bd6b46..61ab41b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,19 @@
+include ext/Makefile
+
 documentation: .phpdoc/build/index.html
 
+.PHONY: unit
+unit: vendor/atoum/atoum/bin/atoum
+	PHP_EXECUTABLE=$(PHP_EXECUTABLE) $<
+
 .PHONY: lint
 lint: vendor/friendsofphp/php-cs-fixer/php-cs-fixer
-	$< fix --dry-run --allow-risky=yes
+	$(PHP_EXECUTABLE) $< fix --dry-run --allow-risky=yes
 
-.phpdoc/build/index.html: vendor/phpdocumentor/phpdocumentor/bin/phpdoc ext/src/wasmer_*.stub.php
-	$<
+.phpdoc/build/index.html: vendor/phpdocumentor/phpdocumentor/bin/phpdoc ext/src/wasmer_*.stub.php src/*.php
+	$(PHP_EXECUTABLE) $<
 
-vendor/phpdocumentor/phpdocumentor/bin/phpdoc vendor/friendsofphp/php-cs-fixer/php-cs-fixer: composer.lock
+vendor/phpdocumentor/phpdocumentor/bin/phpdoc vendor/friendsofphp/php-cs-fixer/php-cs-fixer vendor/atoum/atoum/bin/atoum: composer.lock
 	composer install
 
 composer.lock: composer.json
diff --git a/composer.json b/composer.json
index da261b7..858c193 100644
--- a/composer.json
+++ b/composer.json
@@ -2,9 +2,13 @@
     "name": "wasm/wasm",
     "description": "A complete and mature WebAssembly runtime for PHP based on Wasmer",
     "type": "library",
+    "require": {
+        "ext-wasm": "*"
+    },
     "require-dev": {
         "phpdocumentor/phpdocumentor": "@dev",
-        "friendsofphp/php-cs-fixer": "9999999-dev"
+        "friendsofphp/php-cs-fixer": "@dev",
+        "atoum/atoum": "@stable"
     },
     "minimum-stability": "dev",
     "license": "MIT",
@@ -16,7 +20,13 @@
     ],
     "config": {
         "platform": {
-            "php": "7.3"
+            "php": "7.3",
+            "ext-wasm": "1.0.0-beta1"
+        }
+    },
+    "autoload": {
+        "psr-4": {
+            "Wasm\\": "src"
         }
     }
 }
diff --git a/composer.lock b/composer.lock
index 0ccaf5b..4baa650 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,9 +4,96 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "7d0ad13dc25dfcf83e3cbf8e72bf5102",
+    "content-hash": "10a43c848f9204db443fd5e3b11fa397",
     "packages": [],
     "packages-dev": [
+        {
+            "name": "atoum/atoum",
+            "version": "4.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/atoum/atoum.git",
+                "reference": "56e9c55cab42086c2eb6bd30fcf1e242f9c51f52"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/atoum/atoum/zipball/56e9c55cab42086c2eb6bd30fcf1e242f9c51f52",
+                "reference": "56e9c55cab42086c2eb6bd30fcf1e242f9c51f52",
+                "shasum": ""
+            },
+            "require": {
+                "ext-hash": "*",
+                "ext-json": "*",
+                "ext-tokenizer": "*",
+                "ext-xml": "*",
+                "php": "^7.2 || ^8.0"
+            },
+            "replace": {
+                "mageekguy/atoum": "*"
+            },
+            "require-dev": {
+                "friendsofphp/php-cs-fixer": "^2"
+            },
+            "suggest": {
+                "atoum/stubs": "Provides IDE support (like autocompletion) for atoum",
+                "ext-mbstring": "Provides support for UTF-8 strings",
+                "ext-xdebug": "Provides code coverage report (>= 2.3)"
+            },
+            "bin": [
+                "bin/atoum"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "classes/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Frédéric Hardy",
+                    "email": "frederic.hardy@atoum.org",
+                    "homepage": "http://blog.mageekbox.net"
+                },
+                {
+                    "name": "François Dussert",
+                    "email": "francois.dussert@atoum.org"
+                },
+                {
+                    "name": "Gérald Croes",
+                    "email": "gerald.croes@atoum.org"
+                },
+                {
+                    "name": "Julien Bianchi",
+                    "email": "julien.bianchi@atoum.org"
+                },
+                {
+                    "name": "Ludovic Fleury",
+                    "email": "ludovic.fleury@atoum.org"
+                }
+            ],
+            "description": "Simple modern and intuitive unit testing framework for PHP 5.3+",
+            "homepage": "http://www.atoum.org",
+            "keywords": [
+                "TDD",
+                "atoum",
+                "test",
+                "unit testing"
+            ],
+            "support": {
+                "issues": "https://github.com/atoum/atoum/issues",
+                "source": "https://github.com/atoum/atoum/tree/4.0.0"
+            },
+            "time": "2020-11-21T17:23:11+00:00"
+        },
         {
             "name": "composer/package-versions-deprecated",
             "version": "dev-master",
@@ -567,16 +654,16 @@
         },
         {
             "name": "jawira/plantuml",
-            "version": "v1.50.0",
+            "version": "v1.51.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/jawira/plantuml.git",
-                "reference": "43c499db01872fe76f7b51ef000abeec5946ba27"
+                "reference": "1d7378023b4a693928d0c9cea417c4859ba8c5af"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/jawira/plantuml/zipball/43c499db01872fe76f7b51ef000abeec5946ba27",
-                "reference": "43c499db01872fe76f7b51ef000abeec5946ba27",
+                "url": "https://api.github.com/repos/jawira/plantuml/zipball/1d7378023b4a693928d0c9cea417c4859ba8c5af",
+                "reference": "1d7378023b4a693928d0c9cea417c4859ba8c5af",
                 "shasum": ""
             },
             "suggest": {
@@ -605,9 +692,9 @@
             ],
             "support": {
                 "issues": "https://github.com/jawira/plantuml/issues",
-                "source": "https://github.com/jawira/plantuml/tree/v1.50.0"
+                "source": "https://github.com/jawira/plantuml/tree/v1.51.0"
             },
-            "time": "2021-01-15T14:05:55+00:00"
+            "time": "2021-02-05T14:05:53+00:00"
         },
         {
             "name": "jean85/pretty-package-versions",
@@ -2152,17 +2239,20 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/php-fig/event-dispatcher.git",
-                "reference": "3ef040d7c05652f55bd05115baf059a445cfc79c"
+                "reference": "aa4f89e91c423b516ff226c50dc83f824011c253"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/event-dispatcher/zipball/3ef040d7c05652f55bd05115baf059a445cfc79c",
-                "reference": "3ef040d7c05652f55bd05115baf059a445cfc79c",
+                "url": "https://api.github.com/repos/php-fig/event-dispatcher/zipball/aa4f89e91c423b516ff226c50dc83f824011c253",
+                "reference": "aa4f89e91c423b516ff226c50dc83f824011c253",
                 "shasum": ""
             },
             "require": {
                 "php": ">=7.2.0"
             },
+            "suggest": {
+                "fig/event-dispatcher-util": "Provides some useful PSR-14 utilities"
+            },
             "default-branch": true,
             "type": "library",
             "extra": {
@@ -2194,7 +2284,7 @@
             "support": {
                 "source": "https://github.com/php-fig/event-dispatcher/tree/master"
             },
-            "time": "2020-09-18T06:44:18+00:00"
+            "time": "2021-02-08T21:15:39+00:00"
         },
         {
             "name": "psr/http-message",
@@ -2383,12 +2473,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/cache.git",
-                "reference": "c5a6aaae3d96e7a757836f285d3b84a3f47d73fa"
+                "reference": "7004ad588e2e75ad10d2c894d2ae913cdcb2ce44"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/cache/zipball/c5a6aaae3d96e7a757836f285d3b84a3f47d73fa",
-                "reference": "c5a6aaae3d96e7a757836f285d3b84a3f47d73fa",
+                "url": "https://api.github.com/repos/symfony/cache/zipball/7004ad588e2e75ad10d2c894d2ae913cdcb2ce44",
+                "reference": "7004ad588e2e75ad10d2c894d2ae913cdcb2ce44",
                 "shasum": ""
             },
             "require": {
@@ -2409,7 +2499,7 @@
             "provide": {
                 "psr/cache-implementation": "1.0|2.0",
                 "psr/simple-cache-implementation": "1.0",
-                "symfony/cache-implementation": "1.0"
+                "symfony/cache-implementation": "1.0|2.0"
             },
             "require-dev": {
                 "cache/integration-tests": "dev-master",
@@ -2471,7 +2561,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-04T17:52:48+00:00"
+            "time": "2021-02-08T10:24:30+00:00"
         },
         {
             "name": "symfony/config",
@@ -2656,17 +2746,17 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/contracts.git",
-                "reference": "1a5d7e520264ca987e2bdd26e8dae98fa0483336"
+                "reference": "95a016d0039112830e33b27665d5045dec14c289"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/contracts/zipball/1a5d7e520264ca987e2bdd26e8dae98fa0483336",
-                "reference": "1a5d7e520264ca987e2bdd26e8dae98fa0483336",
+                "url": "https://api.github.com/repos/symfony/contracts/zipball/95a016d0039112830e33b27665d5045dec14c289",
+                "reference": "95a016d0039112830e33b27665d5045dec14c289",
                 "shasum": ""
             },
             "require": {
                 "php": ">=7.2.5",
-                "psr/cache": "^1.0|^2.0",
+                "psr/cache": "^1.0|^2.0|^3.0",
                 "psr/container": "^1.0",
                 "psr/event-dispatcher": "^1.0"
             },
@@ -2747,7 +2837,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-04T17:52:48+00:00"
+            "time": "2021-02-05T17:04:25+00:00"
         },
         {
             "name": "symfony/dependency-injection",
@@ -2755,12 +2845,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/dependency-injection.git",
-                "reference": "6676af032bc256e35f2b4052dc044a6740e6d4f3"
+                "reference": "154ae8cd47631d19a784a88f7c479f96129656a7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/dependency-injection/zipball/6676af032bc256e35f2b4052dc044a6740e6d4f3",
-                "reference": "6676af032bc256e35f2b4052dc044a6740e6d4f3",
+                "url": "https://api.github.com/repos/symfony/dependency-injection/zipball/154ae8cd47631d19a784a88f7c479f96129656a7",
+                "reference": "154ae8cd47631d19a784a88f7c479f96129656a7",
                 "shasum": ""
             },
             "require": {
@@ -2778,7 +2868,7 @@
             },
             "provide": {
                 "psr/container-implementation": "1.0",
-                "symfony/service-implementation": "1.0"
+                "symfony/service-implementation": "1.0|2.0"
             },
             "require-dev": {
                 "symfony/config": "^5.1",
@@ -2835,7 +2925,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-28T15:56:06+00:00"
+            "time": "2021-02-08T10:24:30+00:00"
         },
         {
             "name": "symfony/dom-crawler",
@@ -3329,16 +3419,16 @@
         },
         {
             "name": "symfony/flex",
-            "version": "v1.12.1",
+            "version": "dev-main",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/flex.git",
-                "reference": "394f3e4dc03ea2a5448aeedc9658c8b596b1d39f"
+                "reference": "0e60b4c24398aee87d436f93d2c9bcd7afe0e492"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/flex/zipball/394f3e4dc03ea2a5448aeedc9658c8b596b1d39f",
-                "reference": "394f3e4dc03ea2a5448aeedc9658c8b596b1d39f",
+                "url": "https://api.github.com/repos/symfony/flex/zipball/0e60b4c24398aee87d436f93d2c9bcd7afe0e492",
+                "reference": "0e60b4c24398aee87d436f93d2c9bcd7afe0e492",
                 "shasum": ""
             },
             "require": {
@@ -3352,10 +3442,11 @@
                 "symfony/phpunit-bridge": "^4.4|^5.0",
                 "symfony/process": "^3.4|^4.4|^5.0"
             },
+            "default-branch": true,
             "type": "composer-plugin",
             "extra": {
                 "branch-alias": {
-                    "dev-main": "1.9-dev"
+                    "dev-main": "1.12-dev"
                 },
                 "class": "Symfony\\Flex\\Flex"
             },
@@ -3377,7 +3468,7 @@
             "description": "Composer plugin for Symfony",
             "support": {
                 "issues": "https://github.com/symfony/flex/issues",
-                "source": "https://github.com/symfony/flex/tree/v1.12.1"
+                "source": "https://github.com/symfony/flex/tree/main"
             },
             "funding": [
                 {
@@ -3393,7 +3484,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-02T16:29:45+00:00"
+            "time": "2021-02-07T18:56:29+00:00"
         },
         {
             "name": "symfony/framework-bundle",
@@ -3401,12 +3492,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/framework-bundle.git",
-                "reference": "e741e262c83725de8700887eef28bbb2c803c5d5"
+                "reference": "f909b27173117f78108804f71a95b28e2e011afe"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/framework-bundle/zipball/e741e262c83725de8700887eef28bbb2c803c5d5",
-                "reference": "e741e262c83725de8700887eef28bbb2c803c5d5",
+                "url": "https://api.github.com/repos/symfony/framework-bundle/zipball/f909b27173117f78108804f71a95b28e2e011afe",
+                "reference": "f909b27173117f78108804f71a95b28e2e011afe",
                 "shasum": ""
             },
             "require": {
@@ -3477,7 +3568,7 @@
                 "symfony/polyfill-intl-icu": "~1.0",
                 "symfony/process": "^4.4|^5.0",
                 "symfony/property-info": "^4.4|^5.0",
-                "symfony/security-bundle": "^5.1",
+                "symfony/security-bundle": "^5.2",
                 "symfony/serializer": "^5.2",
                 "symfony/stopwatch": "^4.4|^5.0",
                 "symfony/string": "^5.0",
@@ -3542,7 +3633,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-03T14:45:17+00:00"
+            "time": "2021-02-08T10:24:30+00:00"
         },
         {
             "name": "symfony/http-foundation",
@@ -3550,12 +3641,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/http-foundation.git",
-                "reference": "2cdb300175d6eeaef3c7bdf5cfe502a5ebcdea88"
+                "reference": "f8474ef5c7a3fe2635fe38792aac7383ec8c3efc"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/http-foundation/zipball/2cdb300175d6eeaef3c7bdf5cfe502a5ebcdea88",
-                "reference": "2cdb300175d6eeaef3c7bdf5cfe502a5ebcdea88",
+                "url": "https://api.github.com/repos/symfony/http-foundation/zipball/f8474ef5c7a3fe2635fe38792aac7383ec8c3efc",
+                "reference": "f8474ef5c7a3fe2635fe38792aac7383ec8c3efc",
                 "shasum": ""
             },
             "require": {
@@ -3616,7 +3707,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-03T04:42:38+00:00"
+            "time": "2021-02-06T10:28:18+00:00"
         },
         {
             "name": "symfony/http-kernel",
@@ -3624,12 +3715,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/http-kernel.git",
-                "reference": "7f5b119c2d4f815ccfc199666e15b7bfbd0f2349"
+                "reference": "a111eed4e73125be6deb8a7eccb94d5de02aea6b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/http-kernel/zipball/7f5b119c2d4f815ccfc199666e15b7bfbd0f2349",
-                "reference": "7f5b119c2d4f815ccfc199666e15b7bfbd0f2349",
+                "url": "https://api.github.com/repos/symfony/http-kernel/zipball/a111eed4e73125be6deb8a7eccb94d5de02aea6b",
+                "reference": "a111eed4e73125be6deb8a7eccb94d5de02aea6b",
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             },
             "require": {
@@ -3664,7 +3755,7 @@
                 "psr/log-implementation": "1.0"
             },
             "require-dev": {
-                "psr/cache": "^1.0|^2.0",
+                "psr/cache": "^1.0|^2.0|^3.0",
                 "symfony/browser-kit": "^4.4|^5.0",
                 "symfony/config": "^5.0",
                 "symfony/console": "^4.4|^5.0",
@@ -3729,7 +3820,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-04T17:52:48+00:00"
+            "time": "2021-02-05T17:04:25+00:00"
         },
         {
             "name": "symfony/monolog-bridge",
@@ -4614,12 +4705,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/routing.git",
-                "reference": "7a26ac4674368bd62ae76a969ee4b5e83d10dcb0"
+                "reference": "a379d9d84dc92b5763e965522f5ac21966ffca23"
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-                "url": "https://api.github.com/repos/symfony/routing/zipball/7a26ac4674368bd62ae76a969ee4b5e83d10dcb0",
-                "reference": "7a26ac4674368bd62ae76a969ee4b5e83d10dcb0",
+                "url": "https://api.github.com/repos/symfony/routing/zipball/a379d9d84dc92b5763e965522f5ac21966ffca23",
+                "reference": "a379d9d84dc92b5763e965522f5ac21966ffca23",
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             },
             "require": {
@@ -4697,7 +4788,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-25T14:08:25+00:00"
+            "time": "2021-02-05T08:40:44+00:00"
         },
         {
             "name": "symfony/stopwatch",
@@ -5090,12 +5181,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/twigphp/Twig.git",
-                "reference": "5a60e72afa8511b63217d27bef3f4b7f074e20e1"
+                "reference": "429f90a02d3bd4a06787ac9bc48c56c4320b58a0"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/twigphp/Twig/zipball/5a60e72afa8511b63217d27bef3f4b7f074e20e1",
-                "reference": "5a60e72afa8511b63217d27bef3f4b7f074e20e1",
+                "url": "https://api.github.com/repos/twigphp/Twig/zipball/429f90a02d3bd4a06787ac9bc48c56c4320b58a0",
+                "reference": "429f90a02d3bd4a06787ac9bc48c56c4320b58a0",
                 "shasum": ""
             },
             "require": {
@@ -5161,7 +5252,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-02-02T15:25:09+00:00"
+            "time": "2021-02-08T09:50:07+00:00"
         },
         {
             "name": "webmozart/assert",
@@ -5227,14 +5318,18 @@
     "minimum-stability": "dev",
     "stability-flags": {
         "phpdocumentor/phpdocumentor": 20,
-        "friendsofphp/php-cs-fixer": 20
+        "friendsofphp/php-cs-fixer": 20,
+        "atoum/atoum": 0
     },
     "prefer-stable": false,
     "prefer-lowest": false,
-    "platform": [],
+    "platform": {
+        "ext-wasm": "*"
+    },
     "platform-dev": [],
     "platform-overrides": {
-        "php": "7.3"
+        "php": "7.3",
+        "ext-wasm": "1.0.0-beta1"
     },
     "plugin-api-version": "2.0.0"
 }
diff --git a/ext/src/wasmer_exception.stub.php b/ext/src/wasmer_exception.stub.php
index 4dc8fe6..14620e8 100644
--- a/ext/src/wasmer_exception.stub.php
+++ b/ext/src/wasmer_exception.stub.php
@@ -1,17 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
 /** @generate-function-entries */
 
-namespace Wasm\Exception {
-    class RuntimeException extends \RuntimeException
-    {
-    }
+namespace Wasm\Exception;
+
+class RuntimeException extends \RuntimeException
+{
+}
 
-    class InstantiationException extends RuntimeException
-    {
-    }
+class InstantiationException extends RuntimeException
+{
+}
 
-    class OutOfBoundsException extends RuntimeException
-    {
-    }
+class OutOfBoundsException extends RuntimeException
+{
 }
diff --git a/ext/src/wasmer_root.stub.php b/ext/src/wasmer_root.stub.php
index 99a8db6..dfea485 100644
--- a/ext/src/wasmer_root.stub.php
+++ b/ext/src/wasmer_root.stub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /** @generate-function-entries */
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -152,7 +154,6 @@ function wasm_engine_delete($engine): bool
 {
 }
 
-
 // Store
 
 /**
@@ -191,7 +192,6 @@ function wasm_store_delete($store): bool
 {
 }
 
-
 ///////////////////////////////////////////////////////////////////////////////
 // Type Representations
 
@@ -222,10 +222,10 @@ function wasm_valtype_new(int $kind)
 /**
  * Delete a valtype.
  *
- * @param resource $valtype A `wasm_valtype_t` resource
+ * @param resource $valtype a `wasm_valtype_t` resource
  *
  * ℹ️ This function does not need to be called if the configuration was used as an argument of
- * `wasm_functype_new`, `wasm_globaltype_new`, `wasm_tabletype_new` or was added to a `\Wasm\Vec\Val`.
+ * `wasm_functype_new`, `wasm_globaltype_new`, `wasm_tabletype_new` or was added to a `\Wasm\Vec\Val`
  *
  * @see wasm_valtype_new()
  */
@@ -347,7 +347,6 @@ function wasm_valkind_is_num(int $kind): bool
 /**
  * Verify whether the given kind is a reference.
  *
- *
  * ```php
  * <?php
  *
@@ -364,7 +363,6 @@ function wasm_valkind_is_ref(int $kind): bool
 {
 }
 
-
 // Function Types
 
 /**
@@ -384,7 +382,7 @@ function wasm_valkind_is_ref(int $kind): bool
  *
  * @return resource A `wasm_functype_t` resource
  */
-function wasm_functype_new(\Wasm\Vec\ValType $params, \Wasm\Vec\ValType $results)
+function wasm_functype_new(Wasm\Vec\ValType $params, Wasm\Vec\ValType $results)
 {
 }
 
@@ -401,13 +399,13 @@ function wasm_functype_delete($functype): bool
 /**
  * @param resource $functype A `wasm_functype_t` resource
  */
-function wasm_functype_params($functype): \Wasm\Vec\ValType
+function wasm_functype_params($functype): Wasm\Vec\ValType
 {
 }
 /**
  * @param resource $functype A `wasm_functype_t` resource
  */
-function wasm_functype_results($functype): \Wasm\Vec\ValType
+function wasm_functype_results($functype): Wasm\Vec\ValType
 {
 }
 /**
@@ -427,7 +425,6 @@ function wasm_functype_as_externtype($functype)
 {
 }
 
-
 // Global Types
 
 /**
@@ -483,7 +480,6 @@ function wasm_globaltype_as_externtype($globaltype)
 {
 }
 
-
 // Limits
 
 /**
@@ -512,7 +508,6 @@ function wasm_limits_max($limits): int
 {
 }
 
-
 // Table Types
 
 /**
@@ -572,7 +567,6 @@ function wasm_tabletype_as_externtype($tabletype)
 {
 }
 
-
 // Memory Types
 
 /**
@@ -634,7 +628,6 @@ function wasm_memorytype_as_externtype($memorytype)
 {
 }
 
-
 // Extern Types
 
 /**
@@ -688,7 +681,6 @@ function wasm_externtype_as_memorytype($externtype)
 {
 }
 
-
 // Import Types
 
 /**
@@ -743,7 +735,6 @@ function wasm_importtype_copy($importtype)
 {
 }
 
-
 // Export Types
 
 /**
@@ -791,7 +782,6 @@ function wasm_exporttype_copy($exporttype)
 {
 }
 
-
 ///////////////////////////////////////////////////////////////////////////////
 // Runtime Objects
 
@@ -861,7 +851,6 @@ function wasm_val_f64(float $val)
 
 // TODO(jubianchi): Add ref
 
-
 // Frames
 
 /**
@@ -903,7 +892,6 @@ function wasm_frame_module_offset($frame): int
 {
 }
 
-
 // Traps
 
 /**
@@ -952,16 +940,14 @@ function wasm_trap_origin($trap)
 /**
  * @param resource $trap A `wasm_trap_t` resource
  */
-function wasm_trap_trace($trap): \Wasm\Vec\Frame
+function wasm_trap_trace($trap): Wasm\Vec\Frame
 {
 }
 
-
 // Foreign Objects
 
 // TODO(jubianchi): Add foreign
 
-
 // Modules
 
 /**
@@ -999,14 +985,14 @@ function wasm_module_validate($store, $module): bool
 /**
  * @param resource $module A `wasm_module_t` resource
  */
-function wasm_module_imports($module): \Wasm\Vec\ImportType
+function wasm_module_imports($module): Wasm\Vec\ImportType
 {
 }
 
 /**
  * @param resource $module A `wasm_module_t` resource
  */
-function wasm_module_exports($module): \Wasm\Vec\ExportType
+function wasm_module_exports($module): Wasm\Vec\ExportType
 {
 }
 
@@ -1086,7 +1072,7 @@ function wasm_func_type($func)
 /**
  * @param resource $func A `wasm_func_t` resource
  */
-function wasm_func_call($func, \Wasm\Vec\Val $args): \Wasm\Vec\Val
+function wasm_func_call($func, Wasm\Vec\Val $args): Wasm\Vec\Val
 {
 }
 
@@ -1099,7 +1085,6 @@ function wasm_func_as_extern($func)
 {
 }
 
-
 // Global Instances
 
 /**
@@ -1180,12 +1165,10 @@ function wasm_global_as_extern($global)
 
 // TODO(jubianchi): Add table
 
-
 // Memory Instances
 
 // TODO(jubianchi): Add memory
 
-
 // Externals
 
 /**
@@ -1259,7 +1242,6 @@ function wasm_extern_as_memory($extern)
 {
 }
 
-
 // Module Instances
 
 /**
@@ -1268,7 +1250,7 @@ function wasm_extern_as_memory($extern)
  *
  * @return resource A `wasm_instance_t` resource
  */
-function wasm_instance_new($store, $module, \Wasm\Vec\Extern $externs)
+function wasm_instance_new($store, $module, Wasm\Vec\Extern $externs)
 {
 }
 
@@ -1286,7 +1268,7 @@ function wasm_instance_delete($instance): bool
 /**
  * @param resource $instance A `wasm_instance_t` resource
  */
-function wasm_instance_exports($instance): \Wasm\Vec\Extern
+function wasm_instance_exports($instance): Wasm\Vec\Extern
 {
 }
 
diff --git a/ext/src/wasmer_vec.stub.php b/ext/src/wasmer_vec.stub.php
index 30f2225..24e3b15 100644
--- a/ext/src/wasmer_vec.stub.php
+++ b/ext/src/wasmer_vec.stub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /** @generate-function-entries */
 
 namespace Wasm\Vec {
diff --git a/phpdoc.dist.xml b/phpdoc.dist.xml
index fc66d8d..0bb8f2f 100644
--- a/phpdoc.dist.xml
+++ b/phpdoc.dist.xml
@@ -10,6 +10,7 @@
         <api>
             <source dsn=".">
                 <path>ext/src</path>
+                <path>src</path>
             </source>
         </api>
     </version>
diff --git a/src/Config.php b/src/Config.php
new file mode 100644
index 0000000..04854e0
--- /dev/null
+++ b/src/Config.php
@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm;
+
+final class Config
+{
+    public const COMPILER_CRANELIFT = WASM_COMPILER_CRANELIFT;
+    public const COMPILER_LLVM = WASM_COMPILER_LLVM;
+    public const COMPILER_SINGLEPASS = WASM_COMPILER_SINGLEPASS;
+    public const ENGINE_JIT = WASM_ENGINE_JIT;
+    public const ENGINE_NATIVE = WASM_ENGINE_NATIVE;
+    public const ENGINE_OBJECT_FILE = WASM_ENGINE_OBJECT_FILE;
+
+    private static $compilers = [self::COMPILER_CRANELIFT, self::COMPILER_LLVM, self::COMPILER_SINGLEPASS];
+    private static $engines = [self::ENGINE_JIT, self::ENGINE_NATIVE, self::ENGINE_OBJECT_FILE];
+
+    /**
+     * @var resource
+     */
+    private $inner;
+
+    public function __construct()
+    {
+        $this->inner = \wasm_config_new();
+    }
+
+    public function __destruct()
+    {
+        try {
+            \wasm_config_delete($this->inner);
+        } catch (\TypeError $error) {
+            if (is_resource($this->inner)) {
+                throw $error;
+            }
+        }
+    }
+
+    /**
+     * @return resource
+     */
+    public function inner()
+    {
+        return $this->inner;
+    }
+
+    public function setCompiler(int $compiler): bool
+    {
+        if (false === in_array($compiler, self::$compilers, true)) {
+            throw new Exception\InvalidArgumentException();
+        }
+
+        return \wasm_config_set_compiler($this->inner, $compiler);
+    }
+
+    public function setEngine(int $engine): bool
+    {
+        if (false === in_array($engine, self::$engines, true)) {
+            throw new Exception\InvalidArgumentException();
+        }
+
+        return \wasm_config_set_engine($this->inner, $engine);
+    }
+}
diff --git a/src/Engine.php b/src/Engine.php
new file mode 100644
index 0000000..4a323eb
--- /dev/null
+++ b/src/Engine.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm;
+
+final class Engine
+{
+    /**
+     * @var resource
+     */
+    private $inner;
+
+    public function __construct(?Config $config = null)
+    {
+        $this->inner = null === $config ? \wasm_engine_new() : \wasm_engine_new_with_config($config->inner());
+    }
+
+    public function __destruct()
+    {
+        try {
+            \wasm_engine_delete($this->inner);
+        } catch (\TypeError $error) {
+            if (is_resource($this->inner)) {
+                throw $error;
+            }
+        }
+    }
+
+    /**
+     * @return resource
+     */
+    public function inner()
+    {
+        return $this->inner;
+    }
+}
diff --git a/src/Exception/InvalidArgumentException.php b/src/Exception/InvalidArgumentException.php
new file mode 100644
index 0000000..4206211
--- /dev/null
+++ b/src/Exception/InvalidArgumentException.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm\Exception;
+
+class InvalidArgumentException extends RuntimeException
+{
+}
diff --git a/src/Store.php b/src/Store.php
new file mode 100644
index 0000000..379fd68
--- /dev/null
+++ b/src/Store.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm;
+
+final class Store
+{
+    /**
+     * @var resource
+     */
+    private $inner;
+
+    public function __construct(Engine $engine)
+    {
+        $this->inner = \wasm_store_new($engine->inner());
+    }
+
+    public function __destruct()
+    {
+        try {
+            \wasm_store_delete($this->inner);
+        } catch (\TypeError $error) {
+            if (is_resource($this->inner)) {
+                throw $error;
+            }
+        }
+    }
+
+    /**
+     * @return resource
+     */
+    public function inner()
+    {
+        return $this->inner;
+    }
+}
diff --git a/src/Type/GlobalType.php b/src/Type/GlobalType.php
new file mode 100644
index 0000000..e903405
--- /dev/null
+++ b/src/Type/GlobalType.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm\Type;
+
+use Wasm\Exception;
+
+final class GlobalType
+{
+    public const MUTABILITY_VAR = WASM_VAR;
+    public const MUTABILITY_CONST = WASM_CONST;
+
+    private static $mutabilities = [self::MUTABILITY_VAR, self::MUTABILITY_CONST];
+
+    /**
+     * @var resource
+     */
+    private $inner;
+
+    /**
+     * @param $globaltype resource
+     */
+    public function __construct($globaltype)
+    {
+        if (false === is_resource($globaltype) && 'wasm_globaltype_t' !== get_resource_type($valtype)) {
+            throw new Exception\InvalidArgumentException();
+        }
+
+        $this->inner = $globaltype;
+    }
+
+    public function __destruct()
+    {
+        try {
+            \wasm_globaltype_delete($this->inner);
+        } catch (\TypeError $error) {
+            if (is_resource($this->inner)) {
+                throw $error;
+            }
+        }
+    }
+
+    /**
+     * @return resource
+     */
+    public function inner()
+    {
+        return $this->inner;
+    }
+
+    public function mutability(): int
+    {
+        return \wasm_globaltype_mutability($this->inner);
+    }
+
+    public function content(): ValType
+    {
+        return new ValType(\wasm_globaltype_content($this->inner));
+    }
+
+    public static function new(ValType $type, int $mutability): self
+    {
+        if (false === in_array($mutability, self::$mutabilities, true)) {
+            throw new Exception\InvalidArgumentException();
+        }
+
+        return new self(\wasm_globaltype_new($type->inner(), $mutability));
+    }
+}
diff --git a/src/Type/ValType.php b/src/Type/ValType.php
new file mode 100644
index 0000000..9d58eda
--- /dev/null
+++ b/src/Type/ValType.php
@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm\Type;
+
+use Wasm\Exception;
+
+final class ValType
+{
+    public const KIND_I32 = WASM_I32;
+    public const KIND_I64 = WASM_I64;
+    public const KIND_F32 = WASM_F32;
+    public const KIND_F64 = WASM_F64;
+    public const KIND_ANYREF = WASM_ANYREF;
+    public const KIND_FUNCREF = WASM_FUNCREF;
+
+    private static $kinds = [self::KIND_I32, self::KIND_I64, self::KIND_F32, self::KIND_F64, self::KIND_ANYREF, self::KIND_FUNCREF];
+
+    /**
+     * @var resource
+     */
+    private $inner;
+
+    /**
+     * @param $valtype resource
+     */
+    public function __construct($valtype)
+    {
+        if (false === is_resource($valtype) && 'wasm_valtype_t' !== get_resource_type($valtype)) {
+            throw new Exception\InvalidArgumentException();
+        }
+
+        $this->inner = $valtype;
+    }
+
+    public function __destruct()
+    {
+        try {
+            \wasm_valtype_delete($this->inner);
+        } catch (\TypeError $error) {
+            if (is_resource($this->inner)) {
+                throw $error;
+            }
+        }
+    }
+
+    /**
+     * @return resource
+     */
+    public function inner()
+    {
+        return $this->inner;
+    }
+
+    public function isNum(): bool
+    {
+        return \wasm_valtype_is_num($this->inner);
+    }
+
+    public function isRef(): bool
+    {
+        return \wasm_valtype_is_ref($this->inner);
+    }
+
+    public function kind(): int
+    {
+        return \wasm_valtype_kind($this->inner);
+    }
+
+    public static function new(int $kind): self
+    {
+        if (false === in_array($kind, self::$kinds, true)) {
+            throw new Exception\InvalidArgumentException();
+        }
+
+        return new self(\wasm_valtype_new($kind));
+    }
+}
diff --git a/src/Wat.php b/src/Wat.php
new file mode 100644
index 0000000..0d72fee
--- /dev/null
+++ b/src/Wat.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Wasm;
+
+final class Wat
+{
+    /**
+     * @see \wat2wasm()
+     */
+    public static function wasm(string $wat): string
+    {
+        return \wat2wasm($wat);
+    }
+}
diff --git a/tests/Wasm/Config.php b/tests/Wasm/Config.php
new file mode 100644
index 0000000..7c84ff6
--- /dev/null
+++ b/tests/Wasm/Config.php
@@ -0,0 +1,56 @@
+<?php declare(strict_types=1);
+
+namespace Wasm\Tests\Units;
+
+use atoum\atoum;
+use Wasm;
+
+class Config extends atoum\test
+{
+    public function testConstruct()
+    {
+        $this
+            ->object(new Wasm\Config())
+        ;
+    }
+
+    public function testDestruct()
+    {
+        $this
+            ->given($config = new Wasm\Config())
+            ->then
+                ->variable($config->__destruct())->isNull()
+                ->variable($config->__destruct())->isNull()
+        ;
+    }
+
+    public function testSetCompiler()
+    {
+        $this
+            ->given($config = new Wasm\Config())
+            ->then
+                ->boolean($config->setCompiler(Wasm\Config::COMPILER_CRANELIFT))->isTrue()
+                ->boolean($config->setCompiler(Wasm\Config::COMPILER_LLVM))->isTrue()
+                ->boolean($config->setCompiler(Wasm\Config::COMPILER_SINGLEPASS))->isTrue()
+            ->given($compiler = 99)
+            ->then
+                ->exception(fn () => $config->setCompiler(($compiler)))
+                    ->isInstanceOf(Wasm\Exception\InvalidArgumentException::class)
+        ;
+    }
+
+    public function testSetEngine()
+    {
+        $this
+            ->given($config = new Wasm\Config())
+            ->then
+                ->boolean($config->setEngine(Wasm\Config::ENGINE_JIT))->isTrue()
+                ->boolean($config->setEngine(Wasm\Config::ENGINE_NATIVE))->isTrue()
+                ->boolean($config->setEngine(Wasm\Config::ENGINE_OBJECT_FILE))->isTrue()
+            ->given($engine = 99)
+            ->then
+                ->exception(fn () => $config->setEngine(($engine)))
+                    ->isInstanceOf(Wasm\Exception\InvalidArgumentException::class)
+        ;
+    }
+}
\ No newline at end of file
diff --git a/tests/Wasm/Engine.php b/tests/Wasm/Engine.php
new file mode 100644
index 0000000..6c32fca
--- /dev/null
+++ b/tests/Wasm/Engine.php
@@ -0,0 +1,49 @@
+<?php declare(strict_types=1);
+
+namespace Wasm\Tests\Units;
+
+use atoum\atoum;
+use Wasm;
+
+class Engine extends atoum\test
+{
+    public function testConstruct()
+    {
+        $this
+            ->given($config = null)
+            ->then
+                ->object(new Wasm\Engine($config))
+            ->given($config = new Wasm\Config())
+            ->then
+                ->object(new Wasm\Engine($config))
+        ;
+
+        // TODO(jubianchi): Enable all compilers
+        $compilers = [Wasm\Config::COMPILER_CRANELIFT/*, Wasm\Config::COMPILER_LLVM, Wasm\Config::COMPILER_SINGLEPASS*/];
+        $engines = [Wasm\Config::ENGINE_JIT, Wasm\Config::ENGINE_NATIVE, Wasm\Config::ENGINE_OBJECT_FILE];
+
+        foreach ($compilers as $compiler) {
+            foreach ($engines as $engine) {
+                $this
+                    ->given(
+                        $config = new Wasm\Config(),
+                        $config->setCompiler($compiler),
+                        $config->setEngine($engine),
+                    )
+                    ->then
+                        ->object(new Wasm\Engine($config))
+                ;
+            }
+        }
+    }
+
+    public function testDestruct()
+    {
+        $this
+            ->given($engine = new Wasm\Engine())
+            ->then
+                ->variable($engine->__destruct())->isNull()
+                ->variable($engine->__destruct())->isNull()
+        ;
+    }
+}
\ No newline at end of file
diff --git a/tests/Wasm/Store.php b/tests/Wasm/Store.php
new file mode 100644
index 0000000..43ad189
--- /dev/null
+++ b/tests/Wasm/Store.php
@@ -0,0 +1,28 @@
+<?php declare(strict_types=1);
+
+namespace Wasm\Tests\Units;
+
+use atoum\atoum;
+use Wasm;
+
+class Store extends atoum\test
+{
+    public function testConstruct()
+    {
+        $this
+            ->given($engine = new Wasm\Engine())
+            ->then
+                ->object(new Wasm\Store($engine))
+        ;
+    }
+
+    public function testDestruct()
+    {
+        $this
+            ->given($store = new Wasm\Store(new Wasm\Engine()))
+            ->then
+                ->variable($store->__destruct())->isNull()
+                ->variable($store->__destruct())->isNull()
+        ;
+    }
+}
\ No newline at end of file
diff --git a/tests/Wasm/Type/GlobalType.php b/tests/Wasm/Type/GlobalType.php
new file mode 100644
index 0000000..4aff0e2
--- /dev/null
+++ b/tests/Wasm/Type/GlobalType.php
@@ -0,0 +1,116 @@
+<?php declare(strict_types=1);
+
+namespace Wasm\Tests\Units\Type;
+
+use atoum\atoum;
+use Wasm;
+use Wasm\Type;
+
+class GlobalType extends atoum\test
+{
+    public function testConstruct()
+    {
+        $this
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_I32))
+            ->then
+                ->object(Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR))
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_I32))
+            ->then
+                ->object(Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_CONST))
+            ->given(
+                $valtype = Type\ValType::new(Type\ValType::KIND_I32),
+                $mutability = 99,
+            )
+            ->then
+                ->exception(fn () => Type\GlobalType::new($valtype, $mutability))
+                    ->isInstanceOf(Wasm\Exception\invalidArgumentException::class)
+        ;
+    }
+
+    public function testDestruct()
+    {
+        $this
+            ->given(
+                $valtype = Type\ValType::new(Type\ValType::KIND_I32),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->variable($globaltype->__destruct())->isNull()
+                ->variable($globaltype->__destruct())->isNull()
+        ;
+    }
+
+    public function testMutability()
+    {
+        $this
+            ->given(
+                $valtype = Type\ValType::new(Type\ValType::KIND_I32),
+                $mutability = Type\GlobalType::MUTABILITY_VAR,
+                $globaltype = Type\GlobalType::new($valtype, $mutability),
+            )
+            ->then
+                ->integer($globaltype->mutability())->isEqualTo($mutability)
+            ->given(
+                $valtype = Type\ValType::new(Type\ValType::KIND_I32),
+                $mutability = Type\GlobalType::MUTABILITY_CONST,
+                $globaltype = Type\GlobalType::new($valtype, $mutability),
+            )
+            ->then
+                ->integer($globaltype->mutability())->isEqualTo($mutability)
+        ;
+    }
+
+    public function testContent()
+    {
+        $this
+            ->given(
+                $kind = Type\ValType::KIND_I32,
+                $valtype = Type\ValType::new($kind),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->object($globaltype->content())
+                ->integer($globaltype->content()->kind())->isEqualTo($kind)
+            ->given(
+                $kind = Type\ValType::KIND_I64,
+                $valtype = Type\ValType::new($kind),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->object($globaltype->content())
+                ->integer($globaltype->content()->kind())->isEqualTo($kind)
+            ->given(
+                $kind = Type\ValType::KIND_F32,
+                $valtype = Type\ValType::new($kind),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->object($globaltype->content())
+                ->integer($globaltype->content()->kind())->isEqualTo($kind)
+            ->given(
+                $kind = Type\ValType::KIND_F64,
+                $valtype = Type\ValType::new($kind),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->object($globaltype->content())
+                ->integer($globaltype->content()->kind())->isEqualTo($kind)
+            ->given(
+                $kind = Type\ValType::KIND_ANYREF,
+                $valtype = Type\ValType::new($kind),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->object($globaltype->content())
+                ->integer($globaltype->content()->kind())->isEqualTo($kind)
+            ->given(
+                $kind = Type\ValType::KIND_FUNCREF,
+                $valtype = Type\ValType::new($kind),
+                $globaltype = Type\GlobalType::new($valtype, Type\GlobalType::MUTABILITY_VAR),
+            )
+            ->then
+                ->object($globaltype->content())
+                ->integer($globaltype->content()->kind())->isEqualTo($kind)
+        ;
+    }
+}
diff --git a/tests/Wasm/Type/ValType.php b/tests/Wasm/Type/ValType.php
new file mode 100644
index 0000000..972024c
--- /dev/null
+++ b/tests/Wasm/Type/ValType.php
@@ -0,0 +1,81 @@
+<?php declare(strict_types=1);
+
+namespace Wasm\Tests\Units\Type;
+
+use atoum\atoum;
+use Wasm;
+use Wasm\Type;
+
+class ValType extends atoum\test
+{
+    public function testNew()
+    {
+        $this
+            ->object(Type\ValType::new(Type\ValType::KIND_I32))
+            ->object(Type\ValType::new(Type\ValType::KIND_I64))
+            ->object(Type\ValType::new(Type\ValType::KIND_F32))
+            ->object(Type\ValType::new(Type\ValType::KIND_F64))
+            ->object(Type\ValType::new(Type\ValType::KIND_ANYREF))
+            ->object(Type\ValType::new(Type\ValType::KIND_FUNCREF))
+            ->given($kind = 99)
+            ->then
+                ->exception(fn () => Type\ValType::new($kind))
+                    ->isInstanceOf(Wasm\Exception\invalidArgumentException::class)
+        ;
+    }
+
+    public function testConstruct()
+    {
+        $this
+            ->given($valtype = \wasm_valtype_new(WASM_I32))
+            ->then
+                ->object(new Type\ValType($valtype))
+        ;
+    }
+
+    public function testDestruct()
+    {
+        $this
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_I32))
+            ->then
+                ->variable($valtype->__destruct())->isNull()
+                ->variable($valtype->__destruct())->isNull()
+        ;
+    }
+
+    public function testIsNum()
+    {
+        $this
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_I32))
+            ->then
+                ->boolean($valtype->isNum())->isTrue()
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_ANYREF))
+            ->then
+                ->boolean($valtype->isNum())->isFalse()
+        ;
+    }
+
+    public function testIsRef()
+    {
+        $this
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_ANYREF))
+            ->then
+                ->boolean($valtype->isRef())->isTrue()
+            ->given($valtype = Type\ValType::new(Type\ValType::KIND_I32))
+            ->then
+                ->boolean($valtype->isRef())->isFalse()
+        ;
+    }
+
+    public function testKind()
+    {
+        $this
+            ->given(
+                $kind = Type\ValType::KIND_ANYREF,
+                $valtype = Type\ValType::new($kind)
+            )
+            ->then
+                ->integer($valtype->kind())->isEqualTo($kind)
+        ;
+    }
+}
diff --git a/tests/Wasm/Wat.php b/tests/Wasm/Wat.php
new file mode 100644
index 0000000..6913573
--- /dev/null
+++ b/tests/Wasm/Wat.php
@@ -0,0 +1,23 @@
+<?php declare(strict_types=1);
+
+namespace Wasm\Tests\Units;
+
+use atoum\atoum;
+use Wasm;
+
+class Wat extends atoum\test
+{
+    public function testWat()
+    {
+        $this
+            ->given($wat = '(module)')
+            ->then
+                ->string(Wasm\Wat::wasm($wat))
+                    ->isNotEmpty()
+            ->given($wat = '(invalid)')
+            ->then
+                ->exception(fn () => Wasm\Wat::wasm($wat))
+                    ->isInstanceOf(Wasm\Exception\RuntimeException::class)
+        ;
+    }
+}
\ No newline at end of file