added tests for headerReducer and HeaderActions

package.json

@@ -103,6 +103,7 @@
     "@types/body-parser": "0.0.33",
     "@types/compression": "0.0.33",
     "@types/cookie-parser": "1.3.30",
+    "@types/deep-freeze": "0.0.29",
     "@types/express": "4.0.34",
     "@types/express-serve-static-core": "4.0.39",
     "@types/hammerjs": "2.0.33",
@@ -123,6 +124,7 @@
     "cookie-parser": "1.4.3",
     "copy-webpack-plugin": "4.0.1",
     "css-loader": "^0.26.0",
+    "deep-freeze": "0.0.1",
     "html-webpack-plugin": "^2.21.0",
     "imports-loader": "0.7.0",
     "istanbul-instrumenter-loader": "^0.2.0",

src/app/header/header.actions.spec.ts

@@ -0,0 +1,22 @@
+import { HeaderActions } from "./header.actions";
+describe("HeaderActions", () => {
+
+  describe("collapse", () => {
+    it("should return a COLLAPSE action", () => {
+      expect(HeaderActions.collapse().type).toEqual(HeaderActions.COLLAPSE);
+    });
+  });
+
+  describe("expand", () => {
+    it("should return an EXPAND action", () => {
+      expect(HeaderActions.expand().type).toEqual(HeaderActions.EXPAND);
+    });
+  });
+
+  describe("toggle", () => {
+    it("should return a TOGGLE action", () => {
+      expect(HeaderActions.toggle().type).toEqual(HeaderActions.TOGGLE);
+    });
+  })
+
+});

src/app/header/header.reducer.spec.ts

@@ -0,0 +1,76 @@
+import * as deepFreeze from "deep-freeze";
+
+import { headerReducer } from "./header.reducer";
+import { HeaderActions } from "./header.actions";
+
+describe("headerReducer", () => {
+
+  it("should return the current state when no valid actions have been made", () => {
+    const state = { navCollapsed: false };
+    const newState = headerReducer(state, {type: 'undefined-action'});
+
+    expect(newState).toEqual(state);
+  });
+
+  it("should start with navCollapsed = true", () => {
+    const initialState = headerReducer(undefined, {type: 'undefined-action'});
+
+    // The navigation starts collapsed
+    expect(initialState.navCollapsed).toEqual(true);
+  });
+
+  it("should set navCollapsed to true in response to the COLLAPSE action", () => {
+    const state = { navCollapsed: false };
+    const action = HeaderActions.collapse();
+    const newState = headerReducer(state, action);
+
+    expect(newState.navCollapsed).toEqual(true);
+  });
+
+  it("should perform the COLLAPSE action without mutating the previous state", () => {
+    const state = { navCollapsed: false };
+    deepFreeze(state);
+
+    const action = HeaderActions.collapse();
+    headerReducer(state, action);
+
+    //no expect required, deepFreeze will ensure an exception is thrown if the state
+    //is mutated, and any uncaught exception will cause the test to fail
+  });
+
+  it("should set navCollapsed to false in response to the EXPAND action", () => {
+    const state = { navCollapsed: true };
+    const action = HeaderActions.expand();
+    const newState = headerReducer(state, action);
+
+    expect(newState.navCollapsed).toEqual(false);
+  });
+
+  it("should perform the EXPAND action without mutating the previous state", () => {
+    const state = { navCollapsed: true };
+    deepFreeze(state);
+
+    const action = HeaderActions.expand();
+    headerReducer(state, action);
+  });
+
+  it("should flip the value of navCollapsed in response to the TOGGLE action", () => {
+    const state1 = { navCollapsed: true };
+    const action = HeaderActions.toggle();
+
+    const state2 = headerReducer(state1, action);
+    const state3 = headerReducer(state2, action);
+
+    expect(state2.navCollapsed).toEqual(false);
+    expect(state3.navCollapsed).toEqual(true);
+  });
+
+  it("should perform the TOGGLE action without mutating the previous state", () => {
+    const state = { navCollapsed: true };
+    deepFreeze(state);
+
+    const action = HeaderActions.toggle();
+    headerReducer(state, action);
+  });
+
+});