Add typedefs for Cypress.LocalStorage.clear (#4168)

* add typedefs for LocalStorage.clear

* clean up unused arguments

* appease the linter

cli/types/index.d.ts

@@ -62,6 +62,20 @@ declare namespace Cypress {
     isHeadless: boolean
   }
 
+  interface LocalStorage {
+    /**
+     * Called internally to clear `localStorage` in two situations.
+     *
+     * 1. Before every test, this is called with no argument to clear all keys.
+     * 2. On `cy.clearLocalStorage(keys)` this is called with `keys` as an argument.
+     *
+     * You should not call this method directly to clear `localStorage`; instead, use `cy.clearLocalStorage(key)`.
+     *
+     * @see https://on.cypress.io/clearlocalstorage
+     */
+    clear: (keys?: string[]) => void
+  }
+
   /**
    * Several libraries are bundled with Cypress by default.
    *
@@ -171,6 +185,11 @@ declare namespace Cypress {
      */
     browser: Browser
 
+    /**
+     * Internal class for LocalStorage management.
+     */
+    LocalStorage: LocalStorage
+
     /**
      * Returns all configuration objects.
      * @see https://on.cypress.io/config

cli/types/tests/cypress-tests.ts

@@ -78,6 +78,12 @@ namespace CypressLogsTest {
   log.get('$el') // $ExpectType JQuery<HTMLElement>
 }
 
+namespace CypressLocalStorageTest {
+  Cypress.LocalStorage.clear = function(keys) {
+    keys // $ExpectType string[] | undefined
+  }
+}
+
 cy.wrap({ foo: [1, 2, 3] })
   .its('foo')
   .each((s: number) => {

packages/driver/src/cypress/local_storage.coffee

@@ -8,15 +8,15 @@ $LocalStorage = {
   localStorage: null
   remoteStorage: null
 
-  clear: (keys, local, remote) ->
+  clear: (keys) ->
     # TODO: update this to utils.throwErrByPath() if uncommented
     # throw new Error("Cypress.LocalStorage is missing local and remote storage references!") if not @localStorage or not @remoteStorage
 
     ## make sure we always have an array here with all falsy values removed
     keys = _.compact([].concat(keys))
 
-    local ?= @localStorage
-    remote ?= @remoteStorage
+    local = @localStorage
+    remote = @remoteStorage
 
     storages = _.compact([local, remote])