added rule (#43)

e2e-testing.md

@@ -22,8 +22,9 @@
   - [4.1 One assertion per one test step method](#41-one-assertion-per-one-test-step-method)
   - [4.2 Use expect for assertions](#42-use-expect-for-assertions)
 - [5\. Files naming](#3-files-naming)
-  - [5.1. Name test files without should at the beggining](#51-name-test-files-without-should-at-the-beggining)
-
+  - [5.1. Name test files without should at the beginning](#51-name-test-files-without-should-at-the-beggining)
+- [6\. Class methods with conditional logic](#6-class-methods-with-conditional-logic)
+  - [6.1. Use ternary operator for conditional logic ](#61-use-ternary-operator-for-conditional-logic)
 
 1\. Factory classes
 --------------
@@ -517,3 +518,43 @@ To make file name shorter, try to avoid using the `should` word at the beginning
 - `shouldBeAbleToEditOwnUserProfile` > `editOwnUserProfile`
 - `shouldBeAbleToChangeTheCourse` > `courseChanging`
 - `shouldUpdateUsername` > `updateUsername`
+
+6\. Class methods with conditional logic
+--------------
+
+#### 6.1. Use ternary operator for conditional logic
+
+Use ternary operator for conditional logic instead of if-else statement because it's more concise and readable.
+
+```typescript
+// ❌ not recommended
+export class CourseViewPage extends LMSEditorBasePage {
+  async assertModuleListItemIsVisible(name?: string): Promise<void> {
+    await test.step('Assert module list item is visible', async () => {
+      if (name) {
+        const moduleListItem = this.listItem.filter({hasText: name});
+
+        await expect(moduleListItem).toBeVisible();
+
+        return;
+      }
+
+      await expect(this.listItem).toBeVisible();
+    });
+  }
+}
+
+// ✅ recommended
+export class CourseViewPage extends LMSEditorBasePage {
+  async assertModuleListItemIsVisible(name?: string): Promise<void> {
+    await test.step('Assert module list item is visible', async () => {
+      const moduleListItem = name
+        ? this.listItem.filter({hasText: name})
+        : this.listItem;
+
+      await expect(moduleListItem).toBeVisible();
+    });
+  }
+}
+
+```