ignore files and folders starting with dot in the tests

also switch folder to the fixture directory because some
rollup plugins rely on `process.cwd()`.

Author: freeman

test/index.test.js

@@ -12,7 +12,7 @@ const constant = konst => () => konst;
 
 const printTree = (nodes, indentLevel = 0) => {
 	const indent = join(times(indentLevel, constant('  ')));
-	return join(nodes.map(node =>
+	return join(nodes.filter(node => node.name[0] !== '.').map(node =>
 		`${indent}${node.name}\n${node.type === 'directory' ? printTree(node.children, indentLevel + 1) : ''}`
 	));
 };
@@ -26,10 +26,13 @@ describe('fixtures', () => {
 		}
 
 		it(fixtureDir, async () => {
+			const prevDir = process.cwd();
+			process.chdir(path.resolve(fixturePath));
 			const output = await microbundle({
 				cwd: path.resolve(fixturePath),
 				formats: 'es,cjs,umd'
 			});
+			process.chdir(prevDir);
 
 			const printedDir = printTree([dirTree(fixturePath)]);