Some env improvements

test/unit/config/gutenberg-env.js

@@ -1,32 +1,12 @@
-global.process.env = {
-	...global.process.env,
-	/*
-	Inject the `IS_GUTENBERG_PLUGIN` global, used for feature flagging.
-
-	The conversion to boolean is required here. Why? Package.json defines
-	IS_GUTENBERG_PLUGIN as follows:
-
-		"config": {
-			"IS_GUTENBERG_PLUGIN": true
-		}
-
-	Webpack then replaces references to IS_GUTENBERG_PLUGIN with a literal value `true`.
-	The file you are reading right now, however, receives a string value "true":
-
-		"true" === process.env.npm_package_config_IS_GUTENBERG_PLUGIN
-
-	The code can only work consistently in both environments when the value of
-	IS_GUTENBERG_PLUGIN is consistent. For this reason, the line below turns the
-	string representation of IS_GUTENBERG_PLUGIN into a boolean value.
-	*/
-	// eslint-disable-next-line @wordpress/is-gutenberg-plugin
-	IS_GUTENBERG_PLUGIN:
-		String( process.env.npm_package_config_IS_GUTENBERG_PLUGIN ) === 'true',
-	/**
-	 * Feature flag guarding features specific to WordPress core.
-	 * It's important to set it to "true" in the test environment
-	 * to ensure the Gutenberg plugin can be cleanly merged into
-	 * WordPress core.
-	 */
-	IS_WORDPRESS_CORE: true,
-};
+/*
+ * Feature flag guarding features specific to WordPress core.
+ * It's important to set it to "true" in the test environment
+ * to ensure the Gutenberg plugin can be cleanly merged into
+ * WordPress core.
+ */
+globalThis.IS_WORDPRESS_CORE = true;
+
+// Inject the `IS_GUTENBERG_PLUGIN` global, used for feature flagging.
+// eslint-disable-next-line @wordpress/is-gutenberg-plugin
+globalThis.IS_GUTENBERG_PLUGIN =
+	String( process.env.npm_package_config_IS_GUTENBERG_PLUGIN ) === 'true';

typings/gutenberg-env/index.d.ts

@@ -9,6 +9,17 @@ declare namespace NodeJS {
 
 declare var process: NodeJS.Process;
 
+/**
+ * Whether the code is running in WordPress with SCRIPT_DEBUG flag.
+ */
 declare var SCRIPT_DEBUG: undefined | boolean;
+
+/**
+ * Whether code is running within the Gutenberg plugin.
+ *
+ * When the codebase is built for the plugin, this variable will be set to `true`.
+ * When building for WordPress Core, it will be set to `false` or `undefined`.
+ */
 declare var IS_GUTENBERG_PLUGIN: undefined | boolean;
+
 declare var IS_WORDPRESS_CORE: undefined | boolean;