Resolved issue: https://github.com/usebruno/bruno/issues/4672 (#5900)

- Added interpolation to setVar method's value field.
- Added playwright test to test the fix.
- Added jest test to test out the fix.

---
Playwright - PASS
Jest - PASS
---

packages/bruno-js/src/bru.js

@@ -228,7 +228,7 @@ class Bru {
       );
     }
 
-    this.runtimeVariables[key] = value;
+    this.runtimeVariables[key] = this.interpolate(value);
   }
 
   getVar(key) {

packages/bruno-js/tests/runtime.spec.js

@@ -246,4 +246,16 @@ describe('runtime', () => {
       expect(result.envVariables.number).toBe(42);
     });
   });
+
+  describe('bru.setVar random variable', () => {
+    it('should not be equal to {{$randomFirstName}}', async () => {
+      const script = `bru.setVar('title', '{{$randomFirstName}}')`;
+
+      const runtime = new ScriptRuntime({ runtime: 'vm2' });
+
+      const result = await runtime.runRequestScript(script, {}, {}, {}, '.', null, process.env);
+
+      expect(result.runtimeVariables.title).not.toBe('{{$randomFirstName}}');
+    });
+  });
 });

tests/interpolation/dynamic-variable/collection/bruno.json

@@ -0,0 +1,9 @@
+{
+  "version": "1",
+  "name": "dynamic-variable-interpolation",
+  "type": "collection",
+  "ignore": [
+    "node_modules",
+    ".git"
+  ]
+}

tests/interpolation/dynamic-variable/collection/set-var-dynamic-variable.bru

@@ -0,0 +1,25 @@
+meta {
+  name: set-var-dynamic-variable
+  type: http
+  seq: 1
+}
+
+post {
+  url:  https://echo.usebruno.com
+  body: json
+  auth: none
+}
+
+headers {
+  Content-Type: application/json
+}
+
+script:pre-request {
+  bru.setVar("title", "{{$randomFirstName}}");
+}
+
+body:json {
+  {
+    "title": "{{title}}"
+  }
+}

tests/interpolation/dynamic-variable/init-user-data/preferences.json

@@ -0,0 +1,6 @@
+{
+  "maximized": true,
+  "lastOpenedCollections": [
+    "{{projectRoot}}/tests/interpolation/dynamic-variable/collection"
+  ]
+}

tests/interpolation/dynamic-variable/set-var-dynamic-variable.spec.ts

@@ -0,0 +1,47 @@
+import { test, expect } from '../../../playwright';
+import { closeAllCollections, openCollectionAndAcceptSandbox } from '../../utils/page';
+
+test.describe.serial('Dynamic Variable Interpolation', () => {
+  test.afterAll(async ({ pageWithUserData: page }) => {
+    // cleanup: close all collections
+    await closeAllCollections(page);
+  });
+
+  test('Verifying if the bru.setVar method interpolates random generator functions properly', async ({ pageWithUserData: page }) => {
+    // Open collection and accept sandbox mode
+    await openCollectionAndAcceptSandbox(page, 'dynamic-variable-interpolation', 'safe');
+
+    // Navigate to the request
+    await page.getByRole('complementary').getByText('set-var-dynamic-variable').click();
+
+    // Send the request
+    await page.getByTestId('send-arrow-icon').click();
+
+    // Wait for the response and verify status code
+    await expect(page.getByTestId('response-status-code')).toHaveText(/200/);
+
+    // Verify response contains the title field and that it's not the literal interpolation string
+    const responsePane = page.locator('.response-pane');
+
+    // Check that the response contains a title field
+    await expect(responsePane).toContainText('"title":');
+
+    // Get the response body text to extract the actual title value
+    const responseBodyText = await responsePane.innerText();
+
+    // Extract the title value from the JSON response
+    const titleMatch = responseBodyText.match(/"title":\s*"([^"]+)"/) ?? [];
+    expect(titleMatch).toBeTruthy();
+
+    const actualTitle = titleMatch[1];
+
+    // Verify that the title is not the literal interpolation string
+    // This ensures that the randomFirstName function was properly interpolated
+    expect(actualTitle).not.toEqual('{{$randomFirstName}}');
+
+    // Additional verification: ensure the title is a string and not empty
+    expect(actualTitle).toBeDefined();
+    expect(typeof actualTitle).toBe('string');
+    expect(actualTitle.length).toBeGreaterThan(0);
+  });
+});