feat(assertions): add "Then I see session storage item"

src/actions/session-storage.ts

@@ -7,7 +7,7 @@ import { When } from '@badeball/cypress-cucumber-preprocessor';
  * When I clear session storage
  * ```
  *
- * Clears [`sessionStorage`](https://developer.mozilla.org/docs/Web/API/Window/sessionStorage) data for all origins with which the test has interacted.
+ * Clear [`sessionStorage`](https://developer.mozilla.org/docs/Web/API/Window/sessionStorage) data for all origins with which the test has interacted.
  *
  * @example
  *
@@ -20,9 +20,7 @@ import { When } from '@badeball/cypress-cucumber-preprocessor';
  * @remarks
  *
  *
- * Cypress automatically clears all session storage _before_ each test to prevent state from being shared across tests when [test isolation](https://docs.cypress.io/guides/core-concepts/writing-and-organizing-tests#Test-Isolation) is enabled.
- *
- * You shouldn't need to use this command unless you're using it to clear sessionStorage inside a single test or test isolation is disabled.
+ * Cypress automatically clears all session storage _before_ each test to prevent state from being shared across tests when [test isolation](https://docs.cypress.io/guides/core-concepts/writing-and-organizing-tests#Test-Isolation) is enabled. You shouldn't need to use this command unless you're using it to clear sessionStorage inside a single test or test isolation is disabled.
  */
 export function When_I_clear_session_storage() {
   cy.clearAllSessionStorage();

src/assertions/index.ts

@@ -10,6 +10,7 @@ export * from './link';
 export * from './local-storage';
 export * from './option';
 export * from './response';
+export * from './session-storage';
 export * from './text';
 export * from './url';
 export * from './value';

src/assertions/session-storage.ts

@@ -0,0 +1,24 @@
+import { Then } from '@badeball/cypress-cucumber-preprocessor';
+
+/**
+ * Then I see session storage item:
+ *
+ * ```gherkin
+ * Then I see session storage item {string}
+ * ```
+ *
+ * Assert session storage item **_exists_**.
+ *
+ * @example
+ *
+ * ```gherkin
+ * Then I see session storage item "key"
+ * ```
+ */
+export function Then_I_see_session_storage_item(key: string) {
+  cy.wrap({}).should(() => {
+    expect(sessionStorage.getItem(key)).to.exist;
+  });
+}
+
+Then('I see session storage item {string}', Then_I_see_session_storage_item);