Ensure reexported components do not throw an error.

Author: Robert Jackson

lib/colocated-broccoli-plugin.js

@@ -150,7 +150,7 @@ module.exports = class ColocatedTemplateProcessor extends Plugin {
           }
         );
 
-        if (!jsContents.includes('export default')) {
+        if (hasTemplate && !jsContents.includes('export default')) {
           let message = `\`${relativePath}\` does not contain a \`default export\`. Did you forget to export the component class?`;
           jsContents = `${jsContents}\nthrow new Error(${JSON.stringify(message)});`;
           prefix = '';

node-tests/colocated-broccoli-plugin-test.js

@@ -137,6 +137,55 @@ describe('ColocatedTemplateCompiler', function() {
     );
   });
 
+  it('works for re-exported component without a template', async function() {
+    input.write({
+      'app-name-here': {
+        'router.js': '// stuff here',
+        components: {
+          'foo.js': `export { default } from 'some-place';`,
+        },
+        templates: {
+          'application.hbs': `{{outlet}}`,
+        },
+      },
+    });
+
+    let tree = new ColocatedTemplateCompiler(input.path());
+
+    output = createBuilder(tree);
+    await output.build();
+
+    assert.deepStrictEqual(output.read(), {
+      'app-name-here': {
+        'router.js': '// stuff here',
+        components: {
+          'foo.js': `export { default } from 'some-place';`,
+        },
+        templates: {
+          'application.hbs': '{{outlet}}',
+        },
+      },
+    });
+
+    await output.build();
+
+    assert.deepStrictEqual(output.changes(), {}, 'NOOP update has no changes');
+
+    input.write({
+      'app-name-here': {
+        'router.js': '// other stuff here',
+      },
+    });
+
+    await output.build();
+
+    assert.deepStrictEqual(
+      output.changes(),
+      { 'app-name-here/router.js': 'change' },
+      'has only related changes'
+    );
+  });
+
   it('works for typescript component class with template', async function() {
     input.write({
       'app-name-here': {