From 76ecc39d27f7c9f8a2859976a4aaa56c0927da7c Mon Sep 17 00:00:00 2001
From: Gaurav Saini <gauravharyana01@gmail.com>
Date: Mon, 24 Feb 2025 17:48:22 +0530
Subject: [PATCH] testcases added for preview command Signed-off-by: Gourav
 <gourav.saini.phe22@iitbhu.ac.in>

---
 src/commands/start/preview.ts    | 40 ++++++++++++++------------------
 test/integration/preview.test.ts | 40 ++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 22 deletions(-)
 create mode 100644 test/integration/preview.test.ts

diff --git a/src/commands/start/preview.ts b/src/commands/start/preview.ts
index dae176ff985..7f056f28e9f 100644
--- a/src/commands/start/preview.ts
+++ b/src/commands/start/preview.ts
@@ -47,8 +47,8 @@ class StartPreview extends Command {
       for (const [key, value] of Object.entries(obj)) {
         if (
           key === '$ref' &&
-                    typeof value === 'string' &&
-                    (value.startsWith('.') || value.startsWith('./') || value.startsWith('../'))
+          typeof value === 'string' &&
+          (value.startsWith('.') || value.startsWith('./') || value.startsWith('../'))
         ) {
           const { filePath } = this.parseRef(value);
           const resolvedPath = path.resolve(basePath, filePath);
@@ -81,12 +81,13 @@ class StartPreview extends Command {
     try {
       const document = await bundle(AsyncAPIFile);
       const fileContent =
-                outputFormat === '.yaml' || outputFormat === '.yml'
-                  ? document.yml()
-                  : JSON.stringify(document.json());
+        outputFormat === '.yaml' || outputFormat === '.yml'
+          ? document.yml()
+          : JSON.stringify(document.json(), null, 2);
       fs.writeFileSync(bundledFilePath, fileContent, { encoding: 'utf-8' });
+      this.log('Bundled file updated successfully.');
     } catch (error: any) {
-      throw new Error(`Error bundling files: ${error.message}`);
+      this.error(`Error bundling files: ${error.message}`);
     }
   }
 
@@ -95,6 +96,8 @@ class StartPreview extends Command {
     const port = flags.port;
     const filePath = args['spec-file'];
 
+    this.log('Starting Studio in preview mode...');
+
     this.specFile = await load(filePath);
     this.metricsMetadata.port = port;
 
@@ -106,9 +109,7 @@ class StartPreview extends Command {
 
     const outputFormat = path.extname(AsyncAPIFile);
     if (!outputFormat) {
-      this.error(
-        'Unable to determine file format from the provided AsyncAPI file.'
-      );
+      this.error('Unable to determine file format from the provided AsyncAPI file.');
     }
 
     const bundledFilePath = `./asyncapi-bundled${outputFormat}`;
@@ -121,29 +122,24 @@ class StartPreview extends Command {
     );
     this.findLocalRefFiles(asyncapiDocument, basePath, filesToWatch);
 
-    const watcher = chokidar.watch(Array.from(filesToWatch), {
-      persistent: true,
-    });
+    const watcher = chokidar.watch(Array.from(filesToWatch), { persistent: true });
 
-    await this.updateBundledFile(
-      AsyncAPIFile,
-      outputFormat,
-      bundledFilePath
-    );
+    await this.updateBundledFile(AsyncAPIFile, outputFormat, bundledFilePath);
 
     watcher.on('change', async (changedPath) => {
       this.log(`File changed: ${changedPath}`);
       try {
-        await this.updateBundledFile(
-          AsyncAPIFile,
-          outputFormat,
-          bundledFilePath
-        );
+        await this.updateBundledFile(AsyncAPIFile, outputFormat, bundledFilePath);
       } catch (error: any) {
         this.error(`Error updating bundled file: ${error.message}`);
       }
     });
 
+    watcher.on('error', (error) => {
+      this.error(`Watcher error: ${error.message}`);
+    });
+
+    this.log(`Starting Studio on port ${port}`);
     startStudio(bundledFilePath, port);
   }
 }
diff --git a/test/integration/preview.test.ts b/test/integration/preview.test.ts
new file mode 100644
index 00000000000..e2da044eeac
--- /dev/null
+++ b/test/integration/preview.test.ts
@@ -0,0 +1,40 @@
+import { test } from '@oclif/test';
+import fs from 'fs';
+import TestHelper from '../helpers';
+import { expect } from 'chai';
+
+const testHelper = new TestHelper();
+const bundledFilePath = './asyncapi-bundled.yml';
+
+describe('start preview', () => {
+  beforeEach(() => {
+    testHelper.createDummyContextFile();
+  });
+
+  afterEach(() => {
+    testHelper.deleteDummyContextFile();
+    if (fs.existsSync(bundledFilePath)) {
+      fs.unlinkSync(bundledFilePath);
+    }
+  });
+
+  test
+    .stderr()
+    .stdout()
+    .command(['start:preview', './test/fixtures/specification.yml'])
+    .it('bundles the AsyncAPI file and starts the studio', ({ stdout, stderr }) => {
+      const output = stdout + stderr;
+      expect(output).to.include('Starting Studio in preview mode...');
+      expect(output).to.include('Bundled file updated successfully.');
+      expect(fs.existsSync(bundledFilePath)).to.be.true;
+    });
+
+  test
+    .stderr()
+    .stdout()
+    .command(['start:preview', 'non-existing-context'])
+    .it('throws error if context does not exist', ({ stdout, stderr }) => {
+      const output = stdout + stderr;
+      expect(output).to.include('ContextError: Context "non-existing-context" does not exist');
+    });
+});