Add Dashicon unit tests.

Adds basic rendering dashicon unit tests.  Related to #641.  The
Dashicon should not render when an icon is not provided.

components/dashicon/test/index.js

@@ -0,0 +1,38 @@
+/**
+ * External dependencies
+ */
+import { expect } from 'chai';
+import { shallow } from 'enzyme';
+
+/**
+ * Internal dependencies
+ */
+import Dashicon from '../';
+
+describe( 'Dashicon', () => {
+	describe( 'basic rendering', () => {
+		it( 'without properties', () => {
+			const dashicon = shallow( <Dashicon /> );
+			// Unrendered element.
+			expect( dashicon.type() ).to.be.null();
+		} );
+
+		it( 'with icon property', () => {
+			const dashicon = shallow( <Dashicon icon="wordpress" /> );
+			// OH NO CAPITAL P DANGIT!
+			expect( dashicon.find( 'title' ).text() ).to.equal( 'Wordpress' );
+			expect( dashicon.hasClass( 'dashicon' ) ).to.be.true();
+			expect( dashicon.hasClass( 'dashicons-wordpress' ) ).to.be.true();
+			expect( dashicon.type() ).to.equal( 'svg' );
+			expect( dashicon.prop( 'xmlns' ) ).to.equal( 'http://www.w3.org/2000/svg' );
+			expect( dashicon.prop( 'width' ) ).to.equal( '20' );
+			expect( dashicon.prop( 'height' ) ).to.equal( '20' );
+			expect( dashicon.prop( 'viewBox' ) ).to.equal( '0 0 20 20' );
+		} );
+
+		it( 'with additional class name', () => {
+			const dashicon = shallow( <Dashicon icon="wordpress" className="capital-p-dangit" /> );
+			expect( dashicon.hasClass( 'capital-p-dangit' ) ).to.be.true();
+		} );
+	} );
+} );

package.json

@@ -35,6 +35,7 @@
     "cross-env": "^3.2.4",
     "deep-freeze": "0.0.1",
     "dirty-chai": "^1.2.2",
+    "enzyme": "^2.8.2",
     "eslint": "^3.17.1",
     "eslint-config-wordpress": "^1.1.0",
     "eslint-plugin-jsx-a11y": "^4.0.0",
@@ -50,6 +51,7 @@
     "pegjs-loader": "^0.5.1",
     "postcss-loader": "^1.3.3",
     "raw-loader": "^0.5.1",
+    "react-test-renderer": "^15.5.4",
     "sass-loader": "^6.0.3",
     "sinon": "^2.1.0",
     "sinon-chai": "^2.9.0",

webpack.config.js

@@ -109,7 +109,7 @@ switch ( process.env.NODE_ENV ) {
 			...config.module.rules,
 		];
 		const testFiles = glob.sync(
-			'./{' + Object.keys( config.entry ).sort() + '}/**/test/*.js'
+			'./{' + Object.keys( config.entry ).concat( 'components' ).sort() + '}/**/test/*.js'
 		);
 		config.entry = [
 			'./date/index.js',