fix(CDPBrowser): report connection errors on failed steps, skip screenshots without rendering

docs/helpers/Lightpanda.md

@@ -62,7 +62,7 @@ These are set automatically and only need overriding for unusual setups:
 
 ## Limitations
 
-*   No screenshots and no screencast: `saveScreenshot` throws.
+*   No screenshots and no screencast: `saveScreenshot` and `saveElementScreenshot` do nothing (a debug message is printed).
 *   No frames or popups.
 *   No scrolling: scroll positions always stay at 0.
 *   Computed styles cover what visibility checks need (`display`, `visibility`, `opacity`,

lib/helper/CDPBrowser.js

@@ -357,8 +357,20 @@ class CDPBrowser extends Helper {
     await this.cdp.connect()
   }
 
+  _beforeStep() {
+    if (this._connectError) throw new Error(this._connectError.message)
+  }
+
   async _before() {
-    if (!this.cdp || !this.cdp.isConnected) await this._connect()
+    this._connectError = null
+    if (!this.cdp || !this.cdp.isConnected) {
+      try {
+        await this._connect()
+      } catch (err) {
+        this._connectError = err
+        throw err
+      }
+    }
     this._navStartWaiters = []
     this._lastMainFrameNav = { loaderId: null, events: {} }
     const { targetId } = await this.cdp.send('Target.createTarget', { url: 'about:blank' })
@@ -1343,7 +1355,8 @@ class CDPBrowser extends Helper {
    */
   async saveScreenshot(fileName) {
     if (this.capabilities.screenshot === false) {
-      throw new Error('saveScreenshot is not supported: this browser has no rendering engine')
+      this.debug('saveScreenshot skipped: this browser has no rendering engine')
+      return
     }
     const outputDir = global.output_dir || '.'
     const res = await this.cdp.send('Page.captureScreenshot', { format: 'png' }, this.sessionId)
@@ -1355,7 +1368,8 @@ class CDPBrowser extends Helper {
    */
   async saveElementScreenshot(locator, fileName) {
     if (this.capabilities.screenshot === false) {
-      throw new Error('saveElementScreenshot is not supported: this browser has no rendering engine')
+      this.debug('saveElementScreenshot skipped: this browser has no rendering engine')
+      return
     }
     const res = await this._run(this._candidates(locator), 'rect')
     if (!res.found) throw new ElementNotFound(locator)

lib/helper/Lightpanda.js

@@ -72,7 +72,7 @@ const config = {}
  *
  * ## Limitations
  *
- * - No screenshots and no screencast: `saveScreenshot` throws.
+ * - No screenshots and no screencast: `saveScreenshot` and `saveElementScreenshot` do nothing (a debug message is printed).
  * - No frames or popups.
  * - No scrolling: scroll positions always stay at 0.
  * - Computed styles cover what visibility checks need (`display`, `visibility`, `opacity`,

test/helper/CDPBrowser_lightpanda_test.js

@@ -66,14 +66,10 @@ describe('Lightpanda helper (self-managed lightpanda serve)', function () {
     await I.dontSeeElement('#does-not-exist')
   })
 
-  it('rejects screenshots with a clear message', async () => {
+  it('skips screenshots without failing', async () => {
     await I.amOnPage('/')
-    try {
-      await I.saveScreenshot('nope.png')
-      throw new Error('should have thrown')
-    } catch (err) {
-      expect(err.message).to.include('no rendering engine')
-    }
+    await I.saveScreenshot('nope.png')
+    expect(fs.existsSync(path.join(global.output_dir || '.', 'nope.png'))).to.be.false
   })
 
   webApiTests.tests()

test/helper/CDPBrowser_obscura_test.js

@@ -80,15 +80,11 @@ describe('Obscura helper (self-managed obscura serve)', function () {
     }
   })
 
-  it('rejects screenshots with a clear message when there is no rendering engine', async function () {
+  it('skips screenshots without failing when there is no rendering engine', async function () {
     await I.amOnPage('/')
-    if (I.capabilities.screenshot !== false) this.skip() // this binary can render; saveScreenshot works instead of throwing
-    try {
-      await I.saveScreenshot('nope.png')
-      throw new Error('should have thrown')
-    } catch (err) {
-      expect(err.message).to.include('no rendering engine')
-    }
+    if (I.capabilities.screenshot !== false) this.skip() // this binary can render; saveScreenshot writes a file instead
+    await I.saveScreenshot('nope.png')
+    expect(fs.existsSync(path.join(global.output_dir || '.', 'nope.png'))).to.be.false
   })
 
   webApiTests.tests()