Added Playwright test for creating and using a free-trial Offer

refs https://www.notion.so/ghost/Critical-Paths-980dd089c3e74a6fbc619271f5a9ce42

- this test will create a free-trial Offer and go through Stripe
  checkout, ensuring the member is created as paid
- also changes some utils to support creating the free-trial offer vs
  just a discounted Offer

ghost/core/test/e2e-browser/admin/tiers.spec.js

@@ -14,7 +14,8 @@ test.describe('Admin', () => {
             const offerName = await createOffer(page, {
                 name: 'Get 5% Off!',
                 tierName,
-                percentOff: 5
+                offerType: 'discount',
+                amount: 5
             });
 
             await page.locator('.gh-nav a[href="#/offers/"]').click();

ghost/core/test/e2e-browser/portal/offers.spec.js

@@ -3,7 +3,44 @@ const {deleteAllMembers, createTier, createOffer, completeStripeSubscription} =
 
 test.describe('Portal', () => {
     test.describe('Offers', () => {
-        test('Uses an offer successfully', async ({page}) => {
+        test('Creates and uses a free-trial Offer', async ({page}) => {
+            page.goto('/ghost');
+            await deleteAllMembers(page);
+            const tierName = 'Portal Tier';
+            await createTier(page, {
+                name: tierName,
+                monthlyPrice: 6,
+                yearlyPrice: 60
+            });
+
+            const offerName = await createOffer(page, {
+                name: 'Black Friday Special',
+                tierName,
+                offerType: 'freeTrial',
+                amount: 14
+            });
+
+            await page.locator('.gh-offers-list .gh-list-row').filter({hasText: offerName}).click();
+            const portalUrl = await page.locator('input#url').inputValue();
+
+            await page.goto(portalUrl);
+            const portalFrame = page.frameLocator('#ghost-portal-root div iframe');
+            await portalFrame.locator('#input-name').fill('Testy McTesterson');
+            await portalFrame.locator('#input-email').fill('testy@example.com');
+            await portalFrame.getByRole('button', {name: 'Start 14-day free trial'}).click();
+
+            await completeStripeSubscription(page);
+
+            await page.waitForSelector('h1.site-title', {state: 'visible'});
+            await page.goto('/ghost');
+            await page.locator('.gh-nav a[href="#/members/"]').click();
+
+            // 1 member, should be Testy, on Portal Tier
+            await expect(page.getByRole('link', {name: 'Testy McTesterson testy@example.com'}), 'Should have 1 paid member').toBeVisible();
+            await expect(page.getByRole('link', {name: tierName}), `Paid member should be on ${tierName}`).toBeVisible();
+        });
+
+        test('Creates and uses a discount Offer', async ({page}) => {
             page.goto('/ghost');
             await deleteAllMembers(page);
             const tierName = 'Portal Tier';
@@ -15,7 +52,8 @@ test.describe('Portal', () => {
             const offerName = await createOffer(page, {
                 name: 'Black Friday Special',
                 tierName: tierName,
-                percentOff: 10
+                offerType: 'discount',
+                amount: 10
             });
 
             await page.locator('.gh-offers-list .gh-list-row').filter({hasText: offerName}).click();

ghost/core/test/e2e-browser/utils/e2e-browser-utils.js

@@ -160,10 +160,11 @@ const createTier = async (page, {name, monthlyPrice, yearlyPrice}) => {
  * @param {object} options
  * @param {string} options.name
  * @param {string} options.tierName
- * @param {number} options.percentOff
+ * @param {string} options.offerType
+ * @param {number} options.amount
  * @returns {Promise<string>} Unique offer name
  */
-const createOffer = async (page, {name, tierName, percentOff}) => {
+const createOffer = async (page, {name, tierName, offerType, amount}) => {
     await page.goto('/ghost');
     await page.locator('.gh-nav a[href="#/offers/"]').click();
 
@@ -199,9 +200,17 @@ const createOffer = async (page, {name, tierName, percentOff}) => {
 
     await page.getByRole('link', {name: 'New offer'}).click();
     await page.locator('input#name').fill(offerName);
-    await page.locator('input#amount').fill(`${percentOff}`);
+
+    if (offerType === 'freeTrial') {
+        await page.getByRole('button', {name: 'Free trial Give free access for a limited time.'}).click();
+        await page.locator('input#trial-duration').fill(`${amount}`);
+    } else if (offerType === 'discount') {
+        await page.locator('input#amount').fill(`${amount}`);
+    }
+
     const priceId = await page.locator(`.gh-select-product-cadence>select>option`).getByText(`${tierName} - Monthly`).getAttribute('value');
     await page.locator('.gh-select-product-cadence>select').selectOption(priceId);
+
     await page.getByRole('button', {name: 'Save'}).click();
     // Wait for the "Saved" button, ensures that next clicks don't trigger the unsaved work modal
     await page.getByRole('button', {name: 'Saved'}).waitFor({