disable an expectations if the checked for date is not displayed

spec/features/projects/life_cycle/overview_page/dialog/update_spec.rb

@@ -131,7 +131,13 @@ RSpec.describe "Edit project phases on project overview page", :js, with_flag: {
         dialog.expect_input("Finish date", value: expected_finish_date)
         dialog.expect_input("Duration", value: planning_duration, disabled: true)
 
-        datepicker.expect_disabled(expected_start_date - 1.day)
+        # The spec uses relative dates. On some occasions, this can mean the expected_start_date
+        # is on the first date of a month. The day before that is then not shown at all.
+        # And because the date is disabled, flatpickr also does not provide a button to move to the previous
+        # month. In total, we cannot check for the date to be disabled in these occasions.
+        if datepicker.displays_date?(expected_start_date - 1.day) && !datepicker.has_previous_month_toggle?
+          datepicker.expect_disabled(expected_start_date - 1.day)
+        end
         datepicker.expect_not_disabled(expected_start_date)
 
         # Set invalid range (finish date before start date) via input field

spec/support/components/datepicker/datepicker.rb

@@ -206,6 +206,15 @@ module Components
       expect(page).to have_css(".flatpickr-day:not(.flatpickr-disabled):not(.flatpickr-non-working-day)[aria-label='#{label}']")
     end
 
+    def displays_date?(date)
+      label = date.strftime("%B %-d, %Y")
+      page.has_css?(".flatpickr-day.flatpickr-disabled[aria-label='#{label}']")
+    end
+
+    def has_previous_month_toggle?
+      page.has_css?(".flatpickr-prev-month")
+    end
+
     protected
 
     def save_button_label