Add tests for zoom level functionality

src/vs/editor/test/common/config/commonEditorConfig.test.ts

+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+import * as assert from 'assert';
+import {EditorZoom} from 'vs/editor/common/config/commonEditorConfig';
+
+suite('Common Editor Config', () => {
+	test('Zoom Level', () => {
+
+		//Zoom levels are defined to go between -9, 9 inclusive
+		var zoom = EditorZoom;
+
+		zoom.setZoomLevel(0);
+		assert.equal(zoom.getZoomLevel(), 0);
+
+		zoom.setZoomLevel(-0);
+		assert.equal(zoom.getZoomLevel(), 0);
+
+		zoom.setZoomLevel(5);
+		assert.equal(zoom.getZoomLevel(), 5);
+
+		zoom.setZoomLevel(-1);
+		assert.equal(zoom.getZoomLevel(), -1);
+
+		zoom.setZoomLevel(9);
+		assert.equal(zoom.getZoomLevel(), 9);
+
+		zoom.setZoomLevel(-9);
+		assert.equal(zoom.getZoomLevel(), -9);
+
+		zoom.setZoomLevel(10);
+		assert.equal(zoom.getZoomLevel(), 9);
+
+		zoom.setZoomLevel(-10);
+		assert.equal(zoom.getZoomLevel(), -9);
+
+		zoom.setZoomLevel(9.1);
+		assert.equal(zoom.getZoomLevel(), 9);
+
+		zoom.setZoomLevel(-9.1);
+		assert.equal(zoom.getZoomLevel(), -9);
+
+		zoom.setZoomLevel(Infinity);
+		assert.equal(zoom.getZoomLevel(), 9);
+
+		zoom.setZoomLevel(Number.NEGATIVE_INFINITY);
+		assert.equal(zoom.getZoomLevel(), -9);
+	});
+});