Add wp-env and utilize for running PHPUnit locally

.gitignore

@@ -9,3 +9,4 @@
 
 # Generated via bin/transform-readme.php
 /readme.txt
+/.wp-env.override.json

.wp-env.json

@@ -0,0 +1,17 @@
+{
+  "env": {
+    "development": {
+      "plugins": [
+        "."
+      ]
+    },
+    "tests": {
+      "plugins": [
+        "."
+      ],
+      "mappings": {
+        "../wordpress-develop": "WordPress/wordpress-develop#trunk"
+      }
+    }
+  }
+}

Gruntfile.js

@@ -109,7 +109,7 @@ module.exports = function (grunt) {
 				.trim()
 				.split(/\n/)
 				.filter(function (file) {
-					return !/^(\.|bin|([^/]+)+\.(json|xml)|Gruntfile\.js|tests|README\.md|CONTRIBUTING\.md|\.wordpress-org|composer\..*|webpack.*)/.test(
+					return !/^(\.|bin|([^/]+)+\.(json|xml)|Gruntfile\.js|tests|README\.md|CONTRIBUTING\.md|\.wordpress-org|composer\..*|webpack.*|phpstan.*)/.test(
 						file
 					);
 				});

bin/ci/install-wp-tests.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+# TODO: This should be eliminated in favor of using Docker on GitHub Actions.
+
 set -e
 
 if [ $# -lt 3 ]; then

composer.json

@@ -13,6 +13,7 @@
     "dealerdirect/phpcodesniffer-composer-installer": "0.7.2",
     "php-stubs/wordpress-stubs": "^5.9.3",
     "phpcompatibility/phpcompatibility-wp": "2.1.3",
+    "wp-cli/wp-cli": "^2.6",
     "wp-coding-standards/wpcs": "2.3.0",
     "yoast/wp-test-utils": "^0.2.2"
   },