Add functions to layouts module for a cleaner API

src/layouts/index.js

@@ -1,9 +1,32 @@
 import romanized from "./romanized";
 import traditional from "./traditional";
 
-const layouts = {
+const layoutStore = {
   romanized: romanized,
   traditional: traditional,
 };
 
+function availableLayouts() {
+  return Object.keys(layoutStore);
+}
+
+function isValidLayout(layout) {
+  return availableLayouts().includes(layout);
+}
+
+function fetchLayout(layout) {
+  if (isValidLayout(layout)) {
+    return layoutStore[layout];
+  } else {
+    const msg = "Invalid Layout : " + layout;
+    throw new Error(msg);
+  }
+}
+
+const layouts = {
+  fetchLayout: fetchLayout,
+  isValidLayout: isValidLayout,
+  availableLayouts: availableLayouts,
+};
+
 export default layouts;

test/layouts.spec.js

@@ -2,9 +2,36 @@ import { expect } from "chai";
 import layouts from "../src/layouts";
 
 describe("layouts", () => {
-  it("should return an object of available layouts", () => {
-    expect(layouts).to.be.an("object");
-    expect(layouts).to.have.property("romanized");
-    expect(layouts).to.have.property("traditional");
+  describe("availableLayouts()", () => {
+    it("should return a list of available layouts", () => {
+      const expected = ["romanized", "traditional"];
+      expect(layouts.availableLayouts()).to.deep.equal(expected);
+    });
+  });
+
+  describe("isValidLayout(layout_name)", () => {
+    it("should return a boolean given a layout name", () => {
+      expect(layouts.isValidLayout("bogus")).to.equal(false);
+      expect(layouts.isValidLayout("random")).to.equal(false);
+
+      expect(layouts.isValidLayout("romanized")).to.equal(true);
+      expect(layouts.isValidLayout("traditional")).to.equal(true);
+    });
+  });
+
+  describe("fetchLayout(layout_name)", () => {
+    it("when valid should return a layout object", () => {
+      expect(layouts.fetchLayout("romanized")).to.be.an("object");
+      expect(() => {
+        layouts.fetchLayout("romanized");
+      }).to.not.throw("Invalid Layout");
+      expect(layouts.fetchLayout("traditional").name).to.equal("traditional");
+    });
+
+    it("when invalid should throw an exception", () => {
+      expect(() => {
+        layouts.fetchLayout("bogus");
+      }).to.throw("Invalid Layout");
+    });
   });
 });