Add first headless test

src/headless/Terminal.test.ts

@@ -0,0 +1,27 @@
+/**
+ * Copyright (c) 2016 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { deepStrictEqual, throws } from 'assert';
+import { Terminal } from 'headless/public/Terminal';
+
+const INIT_COLS = 80;
+const INIT_ROWS = 24;
+
+describe('Headless Terminal', () => {
+  let term: Terminal;
+  const termOptions = {
+    cols: INIT_COLS,
+    rows: INIT_ROWS
+  };
+
+  beforeEach(() => {
+    term = new Terminal(termOptions);
+  });
+
+  it('should throw when trying to change cols or rows', () => {
+    throws(() => term.setOption('cols', 1000));
+    throws(() => term.setOption('rows', 1000));
+  });
+});