Minitest/Capybara Dropdown Menu Locator Problem - ruby

Question

I tried to choose four dropdown menu respectively like this:
find(:xpath, '//select[#id = 'homework_filter_program_id']/option[1]').click_on
find(:xpath, '//select[#id = 'homework_filter_lesson_id']/option[1]').select_option
find(:xpath, '//select[#id = 'homework_filter_unit_id']/option[1]').select_option
find(:xpath, '//select[#id = 'homework_filter_difficulty_level_id']/option[1]').select_option
I tried both click_on and select_option to choose.
I derived the locators from this segment.
enter image description here
But I get these errors:
in block in require
in load_dependency
in <top (required)>
What is the wrong thing in my XPath, it doesn't select. I am newbie in Minitest and Ruby.
I am also open suggestions regarding CSS selectors for dropdown menu.

Answer 1

As Paul points out your quotes are invalid, but beyond that there's no need for XPath here. CSS is easier to read and is generally more efficient for locating elements when it can be used. Something along the lines of
find('select#homework_filter_lesson_id option:first-child').select_option
should work (assuming the select is actually visible on the page). Even easier yet would be to just do
select('text of the first option', from: 'homework_filter_lesson_id')

Answer 2

It seems there's an issue with building the xpath locator string (which you're passing as a second argument to find).
'//select[#id = 'homework_filter_program_id']/option[1]'
This isn't valid ruby code.
What you're looking for is string interpolation. There are two common ways of doing that:
"//select[#id = #{homework_filter_program_id}]/option[1]"
Notice the #{} expression inside the string. The result of the expression is interpolated. Keep in mind that this only works with doubly quoted strings ("like this one")
Or use the string formatting:
'//select[#id = %s]/option[1]' % homework_filter_program_id
Notice the %s placeholder. This works very much like sprintf.
Upd: for some reason as I've read your example I figured you had the local variables called homework_filter_program_id etc. Now that I've also looked at the screenshot I realized that homework_filter_program_id is actually the id of an element you want to find.
Your code will most likely work once you drop the unnecessary quotation marks:
'//select[#id=homework_filter_program_id]/option[1]'
But you probably still want to parameterize this locator, and that's when the interpolation advice will come handy.