Add footer tests and improve table documentation

src/file/footer-wrapper.spec.ts

@@ -0,0 +1,29 @@
+import { expect } from "chai";
+import * as sinon from "sinon";
+
+import { FooterWrapper } from "./footer-wrapper";
+import { Media } from "./media";
+import { Paragraph } from "./paragraph";
+import { Table } from "./table";
+
+describe("FooterWrapper", () => {
+    describe("#addParagraph", () => {
+        it("should call the underlying footer's addParagraph", () => {
+            const file = new FooterWrapper(new Media(), 1);
+            const spy = sinon.spy(file.Footer, "addParagraph");
+            file.addParagraph(new Paragraph());
+
+            expect(spy.called).to.equal(true);
+        });
+    });
+
+    describe("#addTable", () => {
+        it("should call the underlying footer's addParagraph", () => {
+            const file = new FooterWrapper(new Media(), 1);
+            const spy = sinon.spy(file.Footer, "addTable");
+            file.addTable(new Table(1, 1));
+
+            expect(spy.called).to.equal(true);
+        });
+    });
+});