add more tests

Author: just-boris

fixtures/components/error-not-a-component/button/index.tsx

@@ -0,0 +1,7 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+export default function Button() {
+  // if a function does not return JSX, we throw
+  return { type: 'button' };
+}

fixtures/components/error-not-a-component/tsconfig.json

@@ -0,0 +1,4 @@
+{
+  "extends": "../tsconfig.json",
+  "include": ["./**/*.tsx"]
+}

src/components/index.ts

@@ -37,6 +37,7 @@ export function documentComponents(
       const moduleSymbol = checker.getSymbolAtLocation(sourceFile);
       const name = componentNameFromPath(sourceFile.fileName);
 
+      // istanbul ignore next
       if (!moduleSymbol) {
         throw new Error(`Unable to resolve module: ${sourceFile.fileName}`);
       }

test/components/errors.test.ts

@@ -14,6 +14,10 @@ test('should throw error when multiple components exported from the main file',
   expect(() => buildProject('ambiguous-exports')).toThrow('Missing default export for Component');
 });
 
+test('should throw error if default export is not a react component', () => {
+  expect(() => buildProject('error-not-a-component')).toThrow('Unknown default export type () => { type: string; }');
+});
+
 test('should throw error if event handler has an invalid type', () => {
   expect(() => buildProject('unknown-event-handler')).toThrow('Unknown event handler type: string');
 });