I would argue that her attitude toward Juliet doesn't change throughout the play. I think that the nurse always wants what is best for Juliet. She wants Juliet to be happy, and she wants her to be well taken care of. What does change about the nurse is how she interacts with Juliet. At the beginning of the play, the nurse is quite comical and very friendly with Juliet. The two verbally spar with each other, and the nurse speaks some fairly raunchy jokes. The nurse encourages Juliet to take the risk with Romeo, and she even plays a major part in organizing the wedding. The nurse is clearly taking active steps to make sure that Juliet gets what she desires, and she does this knowing that it would make the Capulet family furious. Even in act 3, scene 5, the nurse defends Juliet's wishes to not marry Paris, and she nurse intervenes on Juliet's behalf when Lord Capulet is berating his daughter. Capulet turns his rage on her, and he verbally attacks the nurse. It's also possible that he physically attacks her, too. It's at this point that the nurse tells Juliet to forget Romeo and marry Paris:

Faith, here it is.

Romeo is banishèd, and all the world to nothing

That he dares ne'er come back to challenge you.

Or, if he do, it needs must be by stealth.

Then, since the case so stands as now it doth,

I think it best you married with the county.

Oh, he’s a lovely gentleman.

Early in the play, the Nurse is a bit stuck in the past, treating Juliet like the little baby she helped raise and telling embarrassing stories.

Later, she first is more adult, about marriage, and then a bit crude, dropping jokes in.

When Tybalt is killed, the Nurse judges Juliet pretty harshly.

However, throughout the play, the Nurse wants to help and protect Juliet, and loves her. That does not change.

In Romeo and Juliet, when Lord Capulet gets angry at Juliet for refusing to marry Paris, how does the nurse's attitude change towards her?

In the past, Nurse has always supported Juliet and been happy to see her do whatever makes her happy.  Nurse even accepted Juliet's secret marriage to Romeo and did whatever she could to help the couple; she carried messages back and forth between the two when they were attempting to arrange a meeting time and place.

However, Juliet's failure to agree to marry County Paris, which her...

How does the nurse's attitude change during the test of Romeo and Juliet?