diff --git a/src/redux/reducer.test.ts b/src/redux/reducer.test.ts
new file mode 100644
index 0000000..29da01a
--- /dev/null
+++ b/src/redux/reducer.test.ts
@@ -0,0 +1,177 @@
+import { reducer } from "./reducer";
+
+import { AuthState } from "./action";
+
+describe("test reducer", () => {
+  const mockUser = {
+    CreatedDate: "mock-created-date",
+    Email: [
+      {
+        Type: "mock-email-type",
+        Value: "mock-email-value",
+      },
+    ],
+    EmailVerified: true,
+    ID: "mock-id",
+    IsActive: true,
+    IsDeleted: true,
+    LastLoginDate: "mock-login-date",
+    LastLoginLocation: "mock-last-login-action",
+    ModifiedDate: "mock-modified-date",
+    PasswordExpirationDate: "mock-password-expiration",
+    Provider: "mock-provider",
+    RegistrationProvider: "-mock-registration-provider",
+    RegistrationSource: "mock-registration-source",
+    SignupDate: "mock-signup-date",
+    Uid: "mock-uid",
+    Description: "mock-error-description",
+    ErrorCode: 403,
+    Message: "mock-error-message",
+  };
+  test("should return isLoading true on LOGIN_POPUP_STARTED action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+    };
+    const state = reducer(mockState, { type: "LOGIN_POPUP_STARTED" });
+    expect(state).toEqual({ isAuthenticated: true, isLoading: true });
+  });
+
+  test("should return same state if user modified date is same on GET_ACCESS_TOKEN_COMPLETE action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+    const state = reducer(mockState, {
+      type: "GET_ACCESS_TOKEN_COMPLETE",
+      user: {
+        ...mockUser,
+        ModifiedDate: "mock-modified-date",
+      },
+    });
+    expect(state).toEqual(mockState);
+  });
+
+  test("should return state with new user if user modified date is different on GET_ACCESS_TOKEN_COMPLETE action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+
+    const mockActionUser = {
+      ...mockUser,
+      ModifiedDate: "different-modified-date",
+      id: "mock-different-id",
+    };
+    const state = reducer(mockState, {
+      type: "GET_ACCESS_TOKEN_COMPLETE",
+      user: mockActionUser,
+    });
+    expect(state).toEqual({ ...mockState, user: mockActionUser });
+  });
+
+  test("should complete login on LOGIN_POPUP_COMPLETE action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+
+    const mockActionUser = {
+      ...mockUser,
+      ModifiedDate: "different-modified-date",
+      id: "mock-different-id",
+    };
+    const state = reducer(mockState, {
+      type: "LOGIN_POPUP_COMPLETE",
+      user: mockActionUser,
+    });
+    expect(state).toEqual({
+      ...mockState,
+      isLoading: false,
+      error: undefined,
+      user: mockActionUser,
+    });
+  });
+
+  test("should un-authenticate user on logout on LOGOUT action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+
+    const state = reducer(mockState, {
+      type: "LOGOUT",
+    });
+    expect(state).toEqual({
+      ...mockState,
+      isAuthenticated: false,
+      user: undefined,
+    });
+  });
+
+  test("should set action error on ERROR action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+
+    const mockActionError = {
+      name: "mock-name",
+      message: "mock-message",
+      stack: "mock-stack",
+    };
+
+    const state = reducer(mockState, {
+      type: "ERROR",
+      error: mockActionError,
+    });
+    expect(state).toEqual({
+      ...mockState,
+      isLoading: false,
+      error: mockActionError,
+    });
+  });
+
+  test("should reset state on INITIALISED action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+
+    const state = reducer(mockState, {
+      type: "INITIALISED",
+    });
+    expect(state).toEqual({
+      ...mockState,
+      isLoading: false,
+      isAuthenticated: false,
+      error: undefined,
+      user: undefined,
+    });
+  });
+
+  test("should reset state on HANDLE_REDIRECT_COMPLETE action", () => {
+    const mockState: AuthState = {
+      isAuthenticated: true,
+      isLoading: false,
+      user: mockUser,
+    };
+
+    const state = reducer(mockState, {
+      type: "HANDLE_REDIRECT_COMPLETE",
+    });
+    expect(state).toEqual({
+      ...mockState,
+      isLoading: false,
+      isAuthenticated: false,
+      error: undefined,
+      user: undefined,
+    });
+  });
+});