cypress-localstorage-commands
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    1.5.0 • Public • Published

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    Cypress localStorage commands

    Extends Cypress' cy commands with localStorage methods. Allows preserving localStorage between tests and disabling localStorage.

    The problems

    • You want to preserve localStorage between Cypress tests.
    • You want to disable localStorage to check error handling.

    This solution

    This solution allows you to use all browser localStorage methods through Cypress commands, and preserve it between tests. It also allows to simulate that localStorage is disabled in the browser.

    Installation

    This module is distributed via npm which is bundled with node and should be installed as one of your project's devDependencies:

    npm i --save-dev cypress-localstorage-commands

    Usage

    cypress-localstorage-commands extends Cypress' cy command.

    Add this line to your project's cypress/support/commands.js:

    import "cypress-localstorage-commands"

    You can now use all next commands:

    Commands

    cy.saveLocalStorage()

    Saves current localStorage values into an internal "snapshot".

    cy.restoreLocalStorage()

    Restores localStorage to previously "snapshot" saved values.

    cy.clearLocalStorageSnapshot()

    Clears localStorage "snapshot" values, so previously saved values are cleaned.

    cy.getLocalStorage(item)

    Gets localStorage item. Equivalent to localStorage.getItem in browser.

    • item (String): Item to get from localStorage.
    cy.setLocalStorage(item, value)

    Sets localStorage item. Equivalent to localStorage.setItem in browser.

    • item (String): Item to set value.
    • value (String): Value to be set.
    cy.removeLocalStorage(item)

    Removes localStorage item. Equivalent to localStorage.removeItem in browser.

    • item (String): Item to be removed.
    cy.disableLocalStorage(options)

    Disables localStorage. It produces localStorage methods to throw errors.

    • options (Object): Options to use when disabling localStorage.
      • withError (Error): If provided, invocations to localStorage methods will throw this error.

    Preserving local storage between tests

    Use cy.saveLocalStorage() to save a snapshot of current localStorage at the end of one test, and use the cy.restoreLocalStorage() command to restore it at the beginning of another one. The usage of beforeEach and afterEach is recommended for this purpose.

    Examples

    Cookies button example

    Next example shows how this package can be used to test a "cookies button" (which theorically sets a flag into localStorage and can be clicked only once)

    describe("Accept cookies button", () => {
      const COOKIES_BUTTON = "#accept-cookies";
    
      before(() => {
        cy.clearLocalStorageSnapshot();
      });
    
      beforeEach(() => {
        cy.restoreLocalStorage();
        cy.visit("/");
      });
    
      afterEach(() => {
        cy.saveLocalStorage();
      });
    
      it("should be visible", () => {
        cy.get(COOKIES_BUTTON).should("be.visible");
      });
    
      it("should not be visible after clicked", () => {
        cy.get(COOKIES_BUTTON).click();
        cy.get(COOKIES_BUTTON).should("not.be.visible");
      });
    
      it("should not be visible after reloading", () => {
        cy.get(COOKIES_BUTTON).should("not.be.visible");
      });
    });

    Note the usage of beforeEach and afterEach for preserving localStorage between all tests. Also cy.clearLocalStorageSnapshot is used in the before statement to avoid possible conflicts with other test files preserving localStorage.

    localStorage assertions

    Based on the previous example, assertions could be added to check values of localStorage:

    describe("localStorage cookies-accepted item", () => {
      beforeEach(() => {
        cy.restoreLocalStorage();
        cy.visit("/");
      });
    
      afterEach(() => {
        cy.saveLocalStorage();
      });
    
      it("should be null first time page is visited", () => {
        cy.getLocalStorage("cookies-accepted").should("equal", null);
      });
    
      it("should be true after clicking cookies button", () => {
        cy.get("#accept-cookies").click();
        cy.getLocalStorage("cookies-accepted").should("equal", "true");
      });
    
      it("should be true after reloading", () => {
        cy.getLocalStorage("cookies-accepted").then(cookiesAccepted => {
          expect(cookiesAccepted).to.equal("true");
        });
      });
    });

    Disabling localStorage

    Use cy.disableLocalStorage() to simulate that localStorage is disabled, producing that any invocation to localStorage.setItem, localStorage.getItem, localStorage.removeItem or localStorage.clear will throw an error. As MDN docs recommend, "developers should make sure to always catch possible exceptions from setItem()". This command allows to test that possible exceptions are handled correctly.

    Note that:

    • Only pages loaded after calling this command will have localStorage disabled, so always use cy.reload or cy.visit after executing it.
    • The localStorage only remains disabled for all pages loaded during the current test. If you want to disable it for multiple tests, execute it in all of them, or in a beforeEach statement.
    • If any of the other plugin commands (except clearLocalStorageSnapshot) is executed while localStorage is disabled, it will do nothing but producing a Cypress log as: "localStorage.setItem is disabled"

    Examples

    Disabling localStorage in a single test

    Based on previous "Accept cookies button" example, next tests could be added:

    //...
    const LOCALSTORAGE_DISABLED_WARNING = "#localstorage-disabled-warning";
    const LOCALSTORAGE_ERROR = "#localstorage-error";
    
    //... should not be visible after clicked
    
    it("should still be visible when reloading if localStorage is disabled", () => {
      cy.disableLocalStorage();
      cy.reload();
      cy.get(COOKIES_BUTTON).should("be.visible");
    });
    
    it("should display warning if localStorage is disabled", () => {
      cy.disableLocalStorage();
      cy.reload();
      cy.get(LOCALSTORAGE_DISABLED_WARNING).should("be.visible");
    });
    
    it("should display localStorage error message", () => {
      cy.disableLocalStorage();
      cy.reload();
      cy.get(LOCALSTORAGE_ERROR).should("have.text", "Error");
    });
    
    // ...should not be visible after reloading

    Disabling localStorage in multiple tests

    describe("when localStorage is disabled", () => {
      beforeEach(() => {
        cy.disableLocalStorage({
          withError: new Error("Disabled by cypress-localstorage-commands"),
        });
        cy.visit("/");
      });
    
      it("should display localStorage warning", () => {
        cy.get("#localstorage-disabled-warning").should("be.visible");
      });
    
      it("should display localStorage error message", () => {
        cy.get("#localstorage-error").should("have.text", "Disabled by cypress-localstorage-commands");
      });
    
      it("should display accept-cookies button disabled", () => {
        cy.get("#accept-cookies").should("be.disabled");
      });
    });

    Usage with TypeScript

    For those writing TypesScript tests in Cypress, this package includes TypeScript declarations.

    Add "cypress-localstorage-commands" to the types property of the tsconfig.json file:

    {
      "compilerOptions": {
        "types": ["cypress", "cypress-localstorage-commands"]
      }
    }

    Or reference the package in the files using it:

    /// <reference types="cypress-localstorage-commands" />

    Contributing

    Contributors are welcome. Please read the contributing guidelines and code of conduct.

    License

    MIT, see LICENSE for details.

    Install

    npm i cypress-localstorage-commands

    DownloadsWeekly Downloads

    102,843

    Version

    1.5.0

    License

    MIT

    Unpacked Size

    23.3 kB

    Total Files

    8

    Last publish

    Collaborators

    • javierbrea