Python selenium does not return the correct element

try updated code below, your locators were not correct the locatos you have added were for the first date picker

Also this click should be done before to show the datepicker not after

calendarInside.find_element(By.CSS_SELECTOR, ".datetimepicker-dummy-input.is-datetimepicker-range").click()

Full code

   import time

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.chrome.service import Service as ChromeService
from webdriver_manager.chrome import ChromeDriverManager


def testCalendar():
    driver = webdriver.Chrome(service=ChromeService(ChromeDriverManager().install()))
    driver.maximize_window()
    driver.implicitly_wait(10)
    driver.get("https://letcode.in/calendar")
    rangeInput = driver.find_element(By.CSS_SELECTOR, ".datetimepicker-dummy-input.is-datetimepicker-range")
    rangeInput.click()
    calendarInside = driver.find_element(By.XPATH,
                                         '//div[contains(@class,"datetimepicker")  and contains(@class,'
                                         '"is-datetimepicker-default")]')
    calendarInside.find_element(By.XPATH, '//button[text()="Clear"]').click()
    dayExpected = [6, 25]

    allDays = calendarInside.find_elements(By.XPATH,
                                           "//div[@class='datepicker is-active']//div[@class='datepicker-date is-current-month']//button")
    for dayfrom in allDays:
        print("dayfrom: " + str(dayfrom.text) + " - expected: " + str(dayExpected[0]))
        if str(dayfrom.text) == str(dayExpected[0]):
            dayfrom.click()
            break
    time.sleep(2)

    allDays = calendarInside.find_elements(By.XPATH, "//div[@class='datepicker is-active']//div[@class='datepicker-date is-current-month']//button")
    for dayto in allDays:
        print("dayto: " + str(dayto.text) + " - expected: " + str(dayExpected[1]))
        if str(dayto.text) == str(dayExpected[1]):
            dayto.click()
            break

    time.sleep(5)
    driver.quit()


def main():
    testCalendar()


if __name__ == "__main__":
    main()

In full disclosure, I’m the author of the Browserist package. Browserist is lightweight, less verbose extension of the Selenium web driver that makes browser automation even easier. Simply install the package with pip install browserist.

Allow me to simplify your code by unlocking the power of XPath conditions to find elements in the DOM.

from browserist import Browser

RIGHT_CALENDAR_XPATH = "/html/body/app-root/app-calender/section[1]/div/div/div[1]/div/div/div[1]/div[2]/nwb-date-picker"

def open_calendar(browser: Browser) -> None:
    browser.click.button(f"{RIGHT_CALENDAR_XPATH}/div[2]/div[1]/div/input[1]")

def select_date_in_open_calendar(date: int, browser: Browser) -> None:
    browser.click.button(f"{RIGHT_CALENDAR_XPATH}//div[contains(@class, 'datepicker-date is-current-month')]/button[contains(text(), '{date}')]")

with Browser() as browser:
    browser.open.url("https://letcode.in/calendar")
    open_calendar(browser)
    select_date_in_open_calendar(5, browser)
    select_date_in_open_calendar(26, browser)

Notes:

• XPath can have built in functions and conditions. First, I search for dates with the is-current-month class – to avoid multiple fields with the same date, e.g. 1 or 30, from previous or next month. Then I pick the element that contains the relevant date number.
• Browserist doesn’t need explicit conditions like expected_conditions or WebDriverWait – it’s already built in so you don’t have to worry about it. Instead, Browserist awaits an element to be fully loaded before it interacts with it. More on this concept here.

Here’s what I get (slowed down as Browserist finishes the job almost in a blink of an eye). I hope this is helpful. Let me know if you have questions?