diff --git a/test/helpers/ast-checker.js b/test/helpers/ast-checker.js
new file mode 100644
index 0000000..2bb78be
--- /dev/null
+++ b/test/helpers/ast-checker.js
@@ -0,0 +1,48 @@
+"use strict"
+
+const astCheckerPlugin = () => {
+  return {
+    postcssPlugin: "ast-checker-plugin",
+    OnceExit(root) {
+      root.walkAtRules(node => {
+        if (typeof node.params !== "string") {
+          throw node.error(
+            `Params must be of type 'string', found '${typeof node.params}' instead`,
+          )
+        }
+
+        if (typeof node.type !== "string") {
+          throw node.error(
+            `Type must be of type 'string', found '${typeof node.type}' instead`,
+          )
+        }
+
+        if (node.type !== "atrule") {
+          throw node.error(
+            `Type must be 'atrule', found '${node.type}' instead`,
+          )
+        }
+
+        if (typeof node.name !== "string") {
+          throw node.error(
+            `Name must be of type 'string', found '${typeof node.name}' instead`,
+          )
+        }
+
+        if (node.nodes && !Array.isArray(node.nodes)) {
+          throw node.error(
+            `Nodes must be of type 'Array' when it is present, found '${typeof node.nodes}' instead`,
+          )
+        }
+
+        if (!("parent" in node)) {
+          throw node.error("AtRule must have a 'parent' property")
+        }
+      })
+    },
+  }
+}
+
+astCheckerPlugin.postcss = true
+
+module.exports = astCheckerPlugin
diff --git a/test/helpers/check-fixture.js b/test/helpers/check-fixture.js
index 849588f..aa8a5d7 100644
--- a/test/helpers/check-fixture.js
+++ b/test/helpers/check-fixture.js
@@ -8,6 +8,7 @@ const postcss = require("postcss")
 
 // plugin
 const atImport = require("../..")
+const astCheckerPlugin = require("./ast-checker")
 
 function read(name, ext) {
   ext = ext || ".css"
@@ -20,7 +21,7 @@ module.exports = function (t, file, opts, postcssOpts, warnings) {
   if (typeof file === "string") file = { name: file, ext: ".css" }
   const { name, ext } = file
 
-  return postcss(atImport(opts))
+  return postcss([atImport(opts), astCheckerPlugin()])
     .process(read(name, ext), postcssOpts || {})
     .then(result => {
       const actual = result.css