Here are some of the sample test cases for Dropdown or combo box.
Check default selected value in dropdown
Check maximum character length display in the dropdown
Check maximum no. of values display in dropdown without scroll bar
Check dropdown should be open by clicking on both box and dropdown arrow
Check once dropdown is selected, you should be able to select values by keyboard arrow keys or mouse scroll even if dropdown is closed.
Check after selecting dropdown, if you press any alphabet key, the respective value should be selected automatically.
Check if user should not able to edit the dropdown value
Check whether drop down values are arranged in alphabetical order
Type an invalid selection option and check the behavior as per expectations.
If scrolling option is available in combo box, test it.
If the input data finds a match for more than one records ,the output will be the 1st matched record
Only select list control: 1. Check for appropriate sign displayed (as arrow) over control. 2. Check for default value that should be displayed or it should be BLANK. 3. Check if mandatory field can accept BLANK value. 4. Check if it should accept numbers or special characters apart from list. 5. Click on the arrow of the control and check if list should be displayed. 6. Check if list is not empty. 7. Check if list contains number of values then “Scroll” option should display and it should be working. 8. Check entering first letter of option in control and value should get selected. 9. Try if we cannot delete selected option in control. We should not be able to delete. 10. Check for alignment of list is associated with control. 11. Check for “TEXT” identifier displayed with the control. 12. Check after clicking on arrow image should display as clicked. 13. Are all the dropdowns on this screen sorted correctly? Alphabetic sorting is the default unless otherwise specified. 14. In drop down list boxes, ensure that the names are not abbreviations / cut short
Select list and User entry control: 1. Check for appropriate sign displayed (as arrow and bubble) over control. 2. Check for default value that should be displayed or it should be BLANK. 3. Check if mandatory field can accept BLANK value. 4. Check if it should accept numbers or special characters apart from list. 5. Click on the arrow of the control and check if list should be displayed. 6. Check if list is not empty. 7. Check if list contains number of values then “Scroll” option should display and it should be working. 8. Check entering first letter of option in control and value should get selected. 9. Try if we cannot delete selected option in control. We should be able to delete. 10. Check if we can ENTER the text in this control. Check for alpha numeric and special characters like @#$ etc. 11. Check if we can select value from list when previously entered text is in the control. 12. Check if we can enter text if previously selected value is available in control. 13. Check for alignment of list is associated with control. 14. Check for “TEXT” identifier displayed with the control. 15. Check after clicking on arrow image should display as clicked. 16. Check entering same value as in list in the control then it should not handle it as a different value.