Add PhantomJS test support and CharMeasure tests

Fixes #534

src/utils/CharMeasure.phantom.ts

@@ -0,0 +1,65 @@
+/**
+ * @license MIT
+ */
+import { ICharMeasure, ITerminal } from '../Interfaces';
+
+declare var assert: Chai.Assert;
+declare var Terminal: ITerminal;
+
+// Do not describe tests unless in PhantomJS environment
+if (typeof Terminal !== 'undefined') {
+
+  const CharMeasure = (<any>Terminal).CharMeasure;
+
+  describe('CharMeasure', () => {
+    const parentElement = document.createElement('div');
+    let charMeasure: ICharMeasure;
+
+    beforeEach(() => {
+      charMeasure = new CharMeasure(parentElement);
+      document.querySelector('#xterm').appendChild(parentElement);
+    });
+
+    afterEach(() => {
+      if (parentElement && parentElement.parentElement) {
+        parentElement.parentElement.removeChild(parentElement);
+      }
+    });
+
+    describe('measure', () => {
+      it('should be performed async on first call', done => {
+        assert.equal(charMeasure.width, null);
+        charMeasure.measure();
+        assert.equal(charMeasure.width, null);
+        setTimeout(() => {
+          assert.isTrue(charMeasure.width > 0);
+          done();
+        }, 0);
+      });
+
+      it('should be performed sync on successive calls', done => {
+        charMeasure.measure();
+        setTimeout(() => {
+          const firstWidth = charMeasure.width;
+          parentElement.style.fontSize = '2em';
+          charMeasure.measure();
+          assert.equal(charMeasure.width, firstWidth * 2);
+          done();
+        }, 0);
+      });
+
+      it('should NOT do a measure when the parent is hidden', done => {
+        charMeasure.measure();
+        setTimeout(() => {
+          const firstWidth = charMeasure.width;
+          parentElement.style.display = 'none';
+          parentElement.style.fontSize = '2em';
+          charMeasure.measure();
+          assert.equal(charMeasure.width, firstWidth);
+          done();
+        }, 0);
+      });
+    });
+  });
+
+}