It is not accurate to say what is the best test for coughing. Coughing may be related to pneumonia, asthma, GERD, etc., and different tests need to be perfected according to the different diseases under consideration. 1. Pneumonia: If the patient shows symptoms such as coughing, coughing up yellow sputum, fever, chest pain, etc., the possibility of pneumonia should be considered. We can consult the doctor as soon as possible for blood test, sputum culture, chest CT and other related examinations. 2. Asthma: If the patient has an irritating cough with episodes of wheezing, mainly at night or in the early morning, the possibility of asthma should be considered. Lung function, bronchodilator test, bronchial provocation test, blood IgE related examination should be completed. 3. Gastroesophageal reflux disease (GERD): If the patient has cough accompanied by acid reflux, heartburn and other symptoms, and mainly in the lying position, GERD should be considered. Gastroscopy, 24-hour esophageal pH monitoring and other related tests are needed. Cough can also be caused by other diseases. Repeated coughing should be followed up with proper investigations to identify the cause of the cough.