fix(babel): exports.hasOwnProperty is not a function (#1175)

* fix: exports.hasOwnProperty is not a function

The Proxy for `this.#exports` did not forward unknown properties to the
underlying Object instance.

fixes #1140

Co-authored-by: Victor Lin <victor.lin@airbnb.com>
Co-authored-by: Anton Evzhakov <anton@evz.name>

.changeset/fair-dolphins-live.md

@@ -0,0 +1,6 @@
+---
+'@linaria/babel-preset': patch
+'@linaria/testkit': patch
+---
+
+Ensure that the Proxy for this.#exports forwards unknown properties to the underlying Object instance.

packages/babel/src/module.ts

@@ -184,7 +184,14 @@ class Module {
 
           return values;
         }
-        const value = this.#lazyValues.get(key)?.();
+        let value: unknown;
+        if (this.#lazyValues.has(key)) {
+          value = this.#lazyValues.get(key)?.();
+        } else {
+          // Support Object.prototype methods on `exports`
+          // e.g `exports.hasOwnProperty`
+          value = Reflect.get(target, key);
+        }
         this.debug('evaluated', 'get %s: %o', key, value);
         return value;
       },

packages/babel/src/transform-stages/3-prepare-for-runtime.ts

@@ -52,6 +52,7 @@ export default function prepareForRuntime(
     ast: true,
     babelrc: false,
     configFile: false,
+    sourceType: 'unambiguous',
   });
 
   const result = babel.transformFromAstSync(file, code, {

packages/babel/src/utils/getTagProcessor.ts

@@ -335,8 +335,11 @@ function getBuilderForIdentifier(
     ...t,
     addDefaultImport: (importedSource: string, nameHint?: string) =>
       addDefault(path, importedSource, { importedType, nameHint }),
-    addNamedImport: (name: string, importedSource: string, nameHint?: string) =>
-      addNamed(path, name, importedSource, { importedType, nameHint }),
+    addNamedImport: (
+      name: string,
+      importedSource: string,
+      nameHint: string = name
+    ) => addNamed(path, name, importedSource, { importedType, nameHint }),
   };
 
   return (...args: BuilderArgs) =>

packages/testkit/src/module.test.ts

@@ -133,6 +133,16 @@ it('has access to the global object', () => {
   ).not.toThrow();
 });
 
+it('has access to Object prototype methods on `exports`', () => {
+  const mod = new Module(getFileName(), options);
+
+  expect(() =>
+    mod.evaluate(dedent`
+    exports.hasOwnProperty('keyss');
+  `)
+  ).not.toThrow();
+});
+
 it("doesn't have access to the process object", () => {
   const mod = new Module(getFileName(), options);