else path not taken in unit testing

I am working on angular 6

I don't have any else statement in my below code.But I am unable to cover branches due to else path not taken .What I need to do to get 100% branch coverage in this case?
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getHeaderDocumentList(documents: any) {
if (documents) {
documents.result.docAttachment.forEach(element => {
this.headerdocumentdetails.push(element.DocumentUniqueID);
});
}
}

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