From 10dda30c7f417a92f782e21368fbb211a679838a Mon Sep 17 00:00:00 2001
From: Dmitry Gozman <dgozman@gmail.com>
Date: Mon, 11 Dec 2023 21:18:48 -0800
Subject: [PATCH] fix(reporters): carefully handle empty lines (#28591)

In some circumstances, like "No tests found" error, reporters produce a
lot of unnecessary empty lines:

```
$ npx playwright test
Error: No tests found




$ <next command>
```

Also, `line` reporter removes the `npx playwright test` command entirely
when `onError` happens before `onBegin`.
---
 packages/playwright/src/reporters/base.ts |  2 +-
 packages/playwright/src/reporters/line.ts | 15 ++++++++++-----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/packages/playwright/src/reporters/base.ts b/packages/playwright/src/reporters/base.ts
index 7e94cb2f6a..de5a26640f 100644
--- a/packages/playwright/src/reporters/base.ts
+++ b/packages/playwright/src/reporters/base.ts
@@ -470,7 +470,7 @@ export function formatError(error: TestError, highlightCode: boolean): ErrorDeta
     tokens.push(snippet);
   }
 
-  if (parsedStack) {
+  if (parsedStack && parsedStack.stackLines.length) {
     tokens.push('');
     tokens.push(colors.dim(parsedStack.stackLines.join('\n')));
   }
diff --git a/packages/playwright/src/reporters/line.ts b/packages/playwright/src/reporters/line.ts
index a44f29d02e..7d875d0f31 100644
--- a/packages/playwright/src/reporters/line.ts
+++ b/packages/playwright/src/reporters/line.ts
@@ -21,6 +21,7 @@ class LineReporter extends BaseReporter {
   private _current = 0;
   private _failures = 0;
   private _lastTest: TestCase | undefined;
+  private _didBegin = false;
 
   override printsToStdio() {
     return true;
@@ -28,8 +29,12 @@ class LineReporter extends BaseReporter {
 
   override onBegin(suite: Suite) {
     super.onBegin(suite);
-    console.log(this.generateStartingMessage());
-    console.log();
+    const startingMessage = this.generateStartingMessage();
+    if (startingMessage) {
+      console.log(startingMessage);
+      console.log();
+    }
+    this._didBegin = true;
   }
 
   override onStdOut(chunk: string | Buffer, test?: TestCase, result?: TestResult) {
@@ -105,15 +110,15 @@ class LineReporter extends BaseReporter {
   override onError(error: TestError): void {
     super.onError(error);
 
-    const message = formatError(error, colors.enabled).message + '\n\n';
-    if (!process.env.PW_TEST_DEBUG_REPORTERS)
+    const message = formatError(error, colors.enabled).message + '\n';
+    if (!process.env.PW_TEST_DEBUG_REPORTERS && this._didBegin)
       process.stdout.write(`\u001B[1A\u001B[2K`);
     process.stdout.write(message);
     console.log();
   }
 
   override async onEnd(result: FullResult) {
-    if (!process.env.PW_TEST_DEBUG_REPORTERS)
+    if (!process.env.PW_TEST_DEBUG_REPORTERS && this._didBegin)
       process.stdout.write(`\u001B[1A\u001B[2K`);
     await super.onEnd(result);
     this.epilogue(false);