[folding] spec that invalid ranges are ignored

[jrieken]

re #48352

• have the provider and file from below
• the provider is being called
• the editor doesn't show folds

 vscode.languages.registerFoldingRangeProvider({ pattern: '**/*.foo' }, new class implements vscode.FoldingRangeProvider {
        provideFoldingRanges(document: vscode.TextDocument, context: vscode.FoldingContext, token: vscode.CancellationToken): vscode.ProviderResult<vscode.FoldingRange[]> {
            return [
                new vscode.FoldingRange(0, document.lineCount, vscode.FoldingRangeKind.Region)
            ]
        }
    });

this is test
this is test
this is test

[jrieken]

It seems that document.lineCount is the culprit... The docs on the ctor aren't very clear and there is no validation/warning message printed...

[aeschli]

Yes, end line must be a line that exists in the document (< document.lineCount).
I updated the spec.

[dbaeumer]

Verified that doc got updated.