test: Adding compat test suite

Author: rschristian

package.json

@@ -30,7 +30,8 @@
 		"transpile:jsx": "microbundle src/jsx.js -o dist/jsx.js --target web --external preact && microbundle dist/jsx.js -o dist/jsx.js -f cjs --external preact",
 		"copy-typescript-definition": "copyfiles -f src/*.d.ts dist",
 		"test": "eslint src test && tsc && npm run test:mocha && npm run bench",
-		"test:mocha": "BABEL_ENV=test mocha -r @babel/register -r test/setup.js test/**/*.test.js",
+		"test:mocha": "BABEL_ENV=test mocha -r @babel/register -r test/setup.js test/**/[!compat]*.test.js && npm run test:mocha:compat",
+		"test:mocha:compat": "BABEL_ENV=test mocha -r @babel/register -r test/setup.js test/compat.test.js",
 		"format": "prettier src/**/*.{d.ts,js} test/**/*.js --write",
 		"prepublishOnly": "npm run build",
 		"release": "npm run build && git commit -am $npm_package_version && git tag $npm_package_version && git push && git push --tags && npm publish"

test/compat.test.js

@@ -0,0 +1,12 @@
+import { render } from '../src';
+import { createElement } from 'preact/compat';
+import { expect } from 'chai';
+
+describe('compat', () => {
+	it('should not duplicate class attribute when className is empty', async () => {
+		let rendered = render(createElement('div', { className: '' }));
+		let expected = `<div class></div>`;
+
+		expect(rendered).to.equal(expected);
+	});
+});