feat(actions): add "When I set environment variable"

https://docs.cypress.io/api/cypress-api/env

src/actions/env.ts

@@ -0,0 +1,37 @@
+import { When } from '@badeball/cypress-cucumber-preprocessor';
+
+/**
+ * When I set environment variable:
+ *
+ * ```gherkin
+ * When I set environment variable {string} to {string}
+ * ```
+ *
+ * @example
+ *
+ * Set environment variable `host` to `http://server.dev.local`:
+ *
+ * ```gherkin
+ * When I set evironment variable "host" to "http://server.dev.local"
+ * ```
+ *
+ * @remarks
+ *
+ * **Scope**
+ *
+ * Environment variables set using `Cypress.env` _are only in scope for the current spec file_.
+ *
+ * Cypress runs each spec file in isolation: the browser is exited between specs. Environment variables added or changed in one spec won't be visible in other specs.
+ *
+ * **Difference between OS-level and Cypress environment variables**
+ *
+ * In Cypress, "environment variables" are variables that are accessible via `Cypress.env`. These are not the same as OS-level environment variables. However, **it is possible to set Cypress environment variables from OS-level environment variables**.
+ */
+export function When_I_set_environment_variable(key: string, value: string) {
+  Cypress.env(key, value);
+}
+
+When(
+  'I set environment variable {string} to {string}',
+  When_I_set_environment_variable
+);

src/actions/index.ts

@@ -4,6 +4,7 @@ export * from './config';
 export * from './cookie';
 export * from './debug';
 export * from './double-click';
+export * from './env';
 export * from './focus';
 export * from './go';
 export * from './intercept';