[Ruby] Fix deselecting options in <select>

1. Add UnsupportedOperationError when trying
   to deselect options of non-multiseect

2. Update select_by_index, deselect_by_index to only
   deselect first option, since index is unique.

3. Add tests to select_spec

rb/lib/selenium/webdriver/support/select.rb

@@ -117,6 +117,7 @@ def select_by(how, what)
         #
         # @param [:text, :index, :value] how How to find the option
         # @param [String] what What value to find the option by.
+        # @raise [Error::UnsupportedOperationError] if the element does not support multiple selections.
         #
         # @see Select#select_by
         #
@@ -181,7 +182,7 @@ def select_by_index(index)
             raise Error::NoSuchElementError, "cannot locate element with index: #{index.inspect}"
           end
 
-          select_options opts
+          select_option opts.first
         end
 
         def select_by_value(value)
@@ -195,6 +196,9 @@ def select_by_value(value)
         end
 
         def deselect_by_text(text)
+          unless multiple?
+            raise Error::UnsupportedOperationError, 'you may only deselect option of a multi-select'
+          end
           opts = find_by_text text
 
           if opts.empty?
@@ -205,6 +209,9 @@ def deselect_by_text(text)
         end
 
         def deselect_by_value(value)
+          unless multiple?
+            raise Error::UnsupportedOperationError, 'you may only deselect option of a multi-select'
+          end
           opts = find_by_value value
 
           if opts.empty?
@@ -215,13 +222,16 @@ def deselect_by_value(value)
         end
 
         def deselect_by_index(index)
+          unless multiple?
+            raise Error::UnsupportedOperationError, 'you may only deselect option of a multi-select'
+          end
           opts = find_by_index index
 
           if opts.empty?
             raise Error::NoSuchElementError, "cannot locate option with index: #{index}"
           end
 
-          deselect_options opts
+          deselect_option opts.first
         end
 
         private

rb/spec/unit/selenium/webdriver/support/select_spec.rb

@@ -259,10 +259,10 @@ module Support
         end
 
         it 'should raise NoSuchElementError if there are no selects to deselect' do
-          expect(select).to receive(:attribute).with(:multiple).and_return('false')
-          expect(select).to receive(:find_elements).at_least(3).times.and_return []
+          expect(multi_select).to receive(:attribute).with(:multiple).and_return('true')
+          expect(multi_select).to receive(:find_elements).at_least(3).times.and_return []
 
-          s = Select.new select
+          s = Select.new multi_select
 
           expect {
             s.deselect_by :index, 12
@@ -276,6 +276,24 @@ module Support
             s.deselect_by :text, 'also not there'
           }.to raise_error(Error::NoSuchElementError)
         end
+
+        it 'should raise UnsupportedOperationError if trying to deselect options in non-multiselect' do
+          expect(select).to receive(:attribute).with(:multiple).and_return('false')
+
+          s = Select.new select
+
+          expect {
+            s.deselect_by :index, 0
+          }.to raise_error(Error::UnsupportedOperationError)
+
+          expect {
+            s.deselect_by :value, 'not there'
+          }.to raise_error(Error::UnsupportedOperationError)
+
+          expect {
+            s.deselect_by :text, 'also not there'
+          }.to raise_error(Error::UnsupportedOperationError)
+        end
       end # Select
 
       describe Select::Escaper do